diff --git a/package-lock.json b/package-lock.json
index 1bb6609..6993c61 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -27,7 +27,7 @@
         "web3": "^4.9.0",
         "web3-validator": "^2.0.6",
         "xrpl": "^3.1.0",
-        "zod": "^3.23.8"
+        "zod": "^3.24.1"
       },
       "devDependencies": {
         "@types/lodash": "^4.17.13",
@@ -4352,10 +4352,9 @@
       }
     },
     "node_modules/zod": {
-      "version": "3.23.8",
-      "resolved": "https://registry.npmjs.org/zod/-/zod-3.23.8.tgz",
-      "integrity": "sha512-XBx9AXhXktjUqnepgTiE5flcKIYWi/rme0Eaj+5Y0lftuGBq+jyRu/md4WnuxqgP1ubdpNCsYEYPxrzVHD8d6g==",
-      "license": "MIT",
+      "version": "3.24.1",
+      "resolved": "https://registry.npmjs.org/zod/-/zod-3.24.1.tgz",
+      "integrity": "sha512-muH7gBL9sI1nciMZV67X5fTKKBLtwpZ5VBp1vsOQzj1MhrBZ4wlVCm3gedKZWLp0Oyel8sIGfeiz54Su+OVT+A==",
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
       }
diff --git a/package.json b/package.json
index ecc0545..c5e1c0a 100644
--- a/package.json
+++ b/package.json
@@ -40,12 +40,12 @@
     "web3": "^4.9.0",
     "web3-validator": "^2.0.6",
     "xrpl": "^3.1.0",
-    "zod": "^3.23.8"
+    "zod": "^3.24.1"
   },
   "devDependencies": {
+    "@types/lodash": "^4.17.13",
     "@types/micro": "^10.0.0",
     "@types/mocha": "^10.0.6",
-    "@types/lodash": "^4.17.13",
     "@types/uuid": "^9.0.8",
     "@types/web3": "^1.2.2",
     "earl": "^1.3.0",
@@ -56,4 +56,4 @@
     "ts-node": "^10.9.2",
     "typescript": "^5.4.5"
   }
-}
\ No newline at end of file
+}
diff --git a/src/blockchains/eth/eth_types.ts b/src/blockchains/eth/eth_types.ts
index e43c0f0..dd565f5 100644
--- a/src/blockchains/eth/eth_types.ts
+++ b/src/blockchains/eth/eth_types.ts
@@ -1,32 +1,41 @@
-export type TraceAction = {
-  author?: string,
-  address?: string,
-  rewardType?: string,
-  callType?: string,
-  from?: string,
-  to?: string,
-  value?: string,
-  balance?: string,
-  refundAddress?: string
-}
+import { z } from "zod"
 
-export type TraceResult = {
-  gasUsed: string,
-  address?: string
-}
+const TraceActionSchema = z.object({
+  author: z.string().optional(),
+  address: z.string().optional(),
+  rewardType: z.string().optional(),
+  callType: z.string().optional(),
+  from: z.string().optional(),
+  to: z.string().optional(),
+  value: z.string().optional(),
+  balance: z.string().optional(),
+  refundAddress: z.string().optional()
+});
 
-export type Trace = {
-  action: TraceAction,
-  blockHash: string,
-  blockNumber: number,
-  result: TraceResult,
-  subtraces: number,
-  traceAddress: number[],
-  transactionHash: string,
-  transactionPosition: number,
-  type: string,
-  error?: string
-}
+
+export type TraceAction = z.infer<typeof TraceActionSchema>
+
+const TraceResultSchema = z.object({
+  gasUsed: z.string(),
+  address: z.string().optional()
+})
+
+export type TraceResult = z.infer<typeof TraceResultSchema>
+
+export const TraceSchema = z.object({
+  action: TraceActionSchema,
+  blockHash: z.string(),
+  blockNumber: z.number(),
+  result: TraceResultSchema.optional().nullable(),
+  subtraces: z.number(),
+  traceAddress: z.array(z.number()),
+  transactionHash: z.string().optional(),
+  transactionPosition: z.number().optional(),
+  type: z.string(),
+  error: z.string().optional()
+})
+
+export type Trace = z.infer<typeof TraceSchema>
 
 export type ETHBlock = {
   baseFeePerGas?: string,
@@ -75,9 +84,9 @@ export type ETHTransfer = {
   valueExactBase36: string,
   blockNumber: number,
   timestamp: number,
-  transactionHash?: string,
-  transactionPosition?: number,
-  internalTxPosition?: number,
+  transactionHash: string,
+  transactionPosition: number,
+  internalTxPosition: number,
   type: string,
   primaryKey?: number,
 }
diff --git a/src/blockchains/eth/eth_worker.ts b/src/blockchains/eth/eth_worker.ts
index fd98c08..21a8b1a 100644
--- a/src/blockchains/eth/eth_worker.ts
+++ b/src/blockchains/eth/eth_worker.ts
@@ -2,7 +2,7 @@ import { logger } from '../../lib/logger';
 import { constructRPCClient } from '../../lib/http_client';
 import { injectDAOHackTransfers, DAO_HACK_FORK_BLOCK } from './lib/dao_hack';
 import { getGenesisTransfers } from './lib/genesis_transfers';
-import { assignInternalTransactionPosition, transactionOrder } from './lib/util'
+import { assignInternalTransactionPosition, doQAETHTransfers, transactionOrder, mergeSortedArrays } from './lib/util'
 import { BaseWorker } from '../../lib/worker_base';
 import { Web3Interface, constructWeb3Wrapper, safeCastToNumber } from './lib/web3_wrapper';
 import { decodeTransferTrace } from './lib/decode_transfers';
@@ -105,13 +105,15 @@ export class ETHWorker extends BaseWorker {
     logger.info(`Fetching transfer events for interval ${fromBlock}:${toBlock}`)
     const [traces, blocks, receipts] = await this.fetchData(fromBlock, toBlock)
     const events: (ETHTransfer | EOB)[] = this.transformPastEvents(fromBlock, toBlock, traces, blocks, receipts)
-    assignInternalTransactionPosition(events)
-    events.push(...collectEndOfBlocks(fromBlock, toBlock, blocks, this.web3Wrapper))
     events.sort(transactionOrder)
+    doQAETHTransfers(events, fromBlock, toBlock)
+    assignInternalTransactionPosition(events)
+    const eobEvents = collectEndOfBlocks(fromBlock, toBlock, blocks, this.web3Wrapper)
+    const mergedEvents = mergeSortedArrays(events, eobEvents, transactionOrder)
 
     this.lastExportedBlock = toBlock
 
-    return events
+    return mergedEvents
   }
 
   async init(): Promise<void> {
diff --git a/src/blockchains/eth/lib/decode_transfers.ts b/src/blockchains/eth/lib/decode_transfers.ts
index c9844ba..22b7376 100644
--- a/src/blockchains/eth/lib/decode_transfers.ts
+++ b/src/blockchains/eth/lib/decode_transfers.ts
@@ -16,8 +16,9 @@ export function decodeTransferTrace(trace: Trace, timestamp: number, web3Wrapper
       valueExactBase36: web3Wrapper.parseHexToBase36String(trace['action']['value']),
       blockNumber: trace['blockNumber'],
       timestamp: timestamp,
-      transactionHash: trace['transactionHash'],
-      transactionPosition: trace['transactionPosition'],
+      transactionHash: trace['transactionHash'] ? trace['transactionHash'] : `mining_${trace['action']['rewardType']}`,
+      transactionPosition: trace['transactionPosition'] ? trace['transactionPosition'] : 0,
+      internalTxPosition: 0,
       type: trace['type']
     };
   }
@@ -26,7 +27,10 @@ export function decodeTransferTrace(trace: Trace, timestamp: number, web3Wrapper
   if (trace['type'] === 'create') {
     assertIsDefined(trace['action']['from'], "'from' field is expected in trace action on 'create' type");
     assertIsDefined(trace['action']['value'], "'value' field is expected in trace action on 'create' type");
+    assertIsDefined(trace['result'], "'result' field is expected in trace on 'create' type");
     assertIsDefined(trace['result']['address'], "'address' field is expected in trace result on 'create' type");
+    assertIsDefined(trace['transactionHash'], "'transactionHash' field is expected in trace on 'create' type");
+    assertIsDefined(trace['transactionPosition'], "'transactionPosition' field is expected in trace on 'create' type");
 
     return {
       from: trace['action']['from'],
@@ -37,6 +41,7 @@ export function decodeTransferTrace(trace: Trace, timestamp: number, web3Wrapper
       timestamp: timestamp,
       transactionHash: trace['transactionHash'],
       transactionPosition: trace['transactionPosition'],
+      internalTxPosition: 0,
       type: trace['type']
     };
   }
@@ -45,6 +50,8 @@ export function decodeTransferTrace(trace: Trace, timestamp: number, web3Wrapper
     assertIsDefined(trace['action']['refundAddress'], "'refundAddress' field is expected in trace action on 'suicide' type");
     assertIsDefined(trace['action']['address'], "'address' field is expected in trace action on 'suicide' type");
     assertIsDefined(trace['action']['balance'], "'balance' field is expected in trace action on 'suicide' type")
+    assertIsDefined(trace['transactionHash'], "'transactionHash' field is expected in trace on 'suicide' type");
+    assertIsDefined(trace['transactionPosition'], "'transactionPosition' field is expected in trace on 'suicide' type");
 
     return {
       from: trace['action']['address'],
@@ -55,6 +62,7 @@ export function decodeTransferTrace(trace: Trace, timestamp: number, web3Wrapper
       timestamp: timestamp,
       transactionHash: trace['transactionHash'],
       transactionPosition: trace['transactionPosition'],
+      internalTxPosition: 0,
       type: trace['type']
     };
   }
@@ -66,6 +74,8 @@ export function decodeTransferTrace(trace: Trace, timestamp: number, web3Wrapper
   assertIsDefined(trace['action']['from'], `'from' field is expected in trace action on ${trace['type']} type`);
   assertIsDefined(trace['action']['value'], `'value' field is expected in trace action on ${trace['type']} type`);
   assertIsDefined(trace['action']['to'], `'to' field is expected in trace action on ${trace['type']} type`);
+  assertIsDefined(trace['transactionHash'], `'transactionHash' field is expected in trace on ${trace['type']} type`);
+  assertIsDefined(trace['transactionPosition'], `'transactionPosition' field is expected in trace on ${trace['type']} type`);
 
   return {
     from: trace['action']['from'],
@@ -76,6 +86,7 @@ export function decodeTransferTrace(trace: Trace, timestamp: number, web3Wrapper
     timestamp: timestamp,
     transactionHash: trace['transactionHash'],
     transactionPosition: trace['transactionPosition'],
+    internalTxPosition: 0,
     type: trace['type']
   };
 }
diff --git a/src/blockchains/eth/lib/end_of_block.ts b/src/blockchains/eth/lib/end_of_block.ts
index 6ccd3d3..fe0eac3 100644
--- a/src/blockchains/eth/lib/end_of_block.ts
+++ b/src/blockchains/eth/lib/end_of_block.ts
@@ -10,6 +10,7 @@ export type EOB = {
     timestamp: number,
     transactionHash: string,
     transactionPosition: number,
+    internalTxPosition: number,
     type: string,
     primaryKey?: number
 };
diff --git a/src/blockchains/eth/lib/fees_decoder.ts b/src/blockchains/eth/lib/fees_decoder.ts
index 05dc188..3176a27 100644
--- a/src/blockchains/eth/lib/fees_decoder.ts
+++ b/src/blockchains/eth/lib/fees_decoder.ts
@@ -26,6 +26,8 @@ export class FeesDecoder {
       blockNumber: safeCastToNumber(this.web3Wrapper.parseHexToNumber(transaction.blockNumber)),
       timestamp: safeCastToNumber(this.web3Wrapper.parseHexToNumber(block.timestamp)),
       transactionHash: transaction.hash,
+      transactionPosition: safeCastToNumber(this.web3Wrapper.parseHexToNumber(transaction.transactionIndex)),
+      internalTxPosition: 0,
       type: 'fee'
     }];
   }
@@ -46,6 +48,8 @@ export class FeesDecoder {
       blockNumber: safeCastToNumber(this.web3Wrapper.parseHexToNumber(transaction.blockNumber)),
       timestamp: safeCastToNumber(this.web3Wrapper.parseHexToNumber(block.timestamp)),
       transactionHash: transaction.hash,
+      transactionPosition: safeCastToNumber(this.web3Wrapper.parseHexToNumber(transaction.transactionIndex)),
+      internalTxPosition: 0,
       type: 'fee_burnt'
     };
   }
@@ -75,6 +79,8 @@ export class FeesDecoder {
         blockNumber: safeCastToNumber(this.web3Wrapper.parseHexToNumber(transaction.blockNumber)),
         timestamp: safeCastToNumber(this.web3Wrapper.parseHexToNumber(block.timestamp)),
         transactionHash: transaction.hash,
+        transactionPosition: safeCastToNumber(this.web3Wrapper.parseHexToNumber(transaction.transactionIndex)),
+        internalTxPosition: 0,
         type: 'fee'
       };
     }
diff --git a/src/blockchains/eth/lib/fetch_data.ts b/src/blockchains/eth/lib/fetch_data.ts
index 08792f6..36aced6 100644
--- a/src/blockchains/eth/lib/fetch_data.ts
+++ b/src/blockchains/eth/lib/fetch_data.ts
@@ -1,11 +1,26 @@
+import { z } from "zod"
+import { logger } from '../../../lib/logger';
 import { filterErrors } from './filter_errors';
 import { Web3Interface } from './web3_wrapper';
-import { Trace, ETHBlock, ETHReceiptsMap, ETHReceipt } from '../eth_types';
+import { Trace, TraceSchema, ETHBlock, ETHReceiptsMap, ETHReceipt } from '../eth_types';
 import { HTTPClientInterface } from '../../../types'
 
 
-export function parseEthInternalTrx(result: Trace[], isETH: boolean, theMergeBlockNumber: number): Trace[] {
-  const traces = filterErrors(result);
+export function parseEthInternalTrx(traceFilterResult: any[], isETH: boolean, theMergeBlockNumber: number): Trace[] {
+  const traces = filterErrors(traceFilterResult).map(t => {
+    try {
+      return TraceSchema.parse(t)
+    }
+    catch (error) {
+      if (error instanceof z.ZodError) {
+        logger.error('Validation failed:\n', error.toString())
+        logger.error('Trying to parse object:\n', JSON.stringify(t));
+      } else {
+        logger.error('An unexpected error occurred:', error);
+      }
+      throw error
+    }
+  })
 
   return traces
     .filter((trace: Trace) =>
diff --git a/src/blockchains/eth/lib/genesis_transfers.ts b/src/blockchains/eth/lib/genesis_transfers.ts
index 9e0edc2..0923744 100644
--- a/src/blockchains/eth/lib/genesis_transfers.ts
+++ b/src/blockchains/eth/lib/genesis_transfers.ts
@@ -12,10 +12,17 @@ const GENESIS_TIMESTAMP = 1438269973;
 
 export function getGenesisTransfers(web3Wrapper: Web3Interface): ETHTransfer[] {
   const result: ETHTransfer[] = [];
+
+  const txHashMap: Map<string, number> = new Map();
+
   GENESIS_TRANSFERS.forEach((transfer) => {
     const [id, from, to, amount] = transfer;
     const wei = web3Wrapper.etherToWei(amount);
 
+    // Used to construct incrementing internal transaction numbers
+    const currentCount = txHashMap.get(from) || 0;
+
+
     result.push({
       from: 'GENESIS',
       to: to,
@@ -24,6 +31,8 @@ export function getGenesisTransfers(web3Wrapper: Web3Interface): ETHTransfer[] {
       blockNumber: 0,
       timestamp: GENESIS_TIMESTAMP,
       transactionHash: from,
+      transactionPosition: currentCount,
+      internalTxPosition: 0,
       type: 'genesis'
     });
   });
@@ -35,6 +44,9 @@ export function getGenesisTransfers(web3Wrapper: Web3Interface): ETHTransfer[] {
     valueExactBase36: BigInt('5000000000000000000').toString(36),
     blockNumber: 0,
     timestamp: GENESIS_TIMESTAMP,
+    transactionHash: 'GENESIS_mining_tx',
+    transactionPosition: 0,
+    internalTxPosition: 0,
     type: 'reward'
   });
 
diff --git a/src/blockchains/eth/lib/util.ts b/src/blockchains/eth/lib/util.ts
index 41504c0..5cbb1f0 100644
--- a/src/blockchains/eth/lib/util.ts
+++ b/src/blockchains/eth/lib/util.ts
@@ -1,7 +1,8 @@
 import { ETHTransfer } from '../eth_types';
+import { EOB } from './end_of_block'
 const { groupBy } = require('lodash');
 
-export function transactionOrder(a: ETHTransfer, b: ETHTransfer) {
+export function transactionOrder(a: ETHTransfer | EOB, b: ETHTransfer | EOB) {
   if (a.blockNumber !== b.blockNumber) {
     return a.blockNumber - b.blockNumber
   }
@@ -21,15 +22,85 @@ export function transactionOrder(a: ETHTransfer, b: ETHTransfer) {
 
 const ethTransferKey = (transfer: ETHTransfer) => `${transfer.blockNumber}-${transfer.transactionHash ?? ''}-${transfer.transactionPosition ?? ''}-${transfer.from}-${transfer.to}`
 
-export function assignInternalTransactionPosition(transfers: ETHTransfer[], groupByKey: (transfer: ETHTransfer) => string = ethTransferKey): ETHTransfer[] {
+export function assignInternalTransactionPosition(transfers: ETHTransfer[], groupByKey: (transfer: ETHTransfer) => string = ethTransferKey): void {
   const grouped = groupBy(transfers, groupByKey)
   const values: ETHTransfer[][] = Object.values(grouped)
 
-  return values.flatMap((transfersSameKey: ETHTransfer[]) => {
+  values.forEach((transfersSameKey: ETHTransfer[]) => {
     transfersSameKey.forEach((transfer: ETHTransfer, index: number) => {
       transfer.internalTxPosition = index
     })
-    return transfersSameKey
   })
 }
 
+export function assertBlocksMatch(groupedTransfers: any, fromBlock: number, toBlock: number) {
+  const keys = Object.keys(groupedTransfers)
+  if (keys.length !== toBlock - fromBlock + 1) {
+    throw new Error(`Wrong number of blocks seen. Expected ${toBlock - fromBlock + 1} got ${keys.length}.`)
+  }
+
+  for (let block = fromBlock; block <= toBlock; block++) {
+    if (!groupedTransfers.hasOwnProperty(block.toString())) {
+      throw new Error(`Missing transfers for block ${block}.`)
+    }
+  }
+}
+
+
+export function assertTransfersWithinBlock(transfersPerBlock: ETHTransfer[]) {
+  let expectedTxPosition = 0
+
+  for (const transfer of transfersPerBlock) {
+    if (transfer.transactionPosition !== expectedTxPosition) {
+      // We allow for multiple transfers withing a transaction. That is why we can see the same transaction position several times.
+      if (transfer.transactionPosition !== expectedTxPosition + 1) {
+        throw new Error(`Unexpected transaction position for transfer: ${JSON.stringify(transfer)}, expected tx position: ${expectedTxPosition} or ${expectedTxPosition + 1}`);
+      }
+      expectedTxPosition += 1
+    }
+  }
+}
+
+
+/**
+ * Assert data quality guarantees on top of input Transfers
+ *
+ * Throw an error if:
+ * 1. A block number is missing
+ * 2. Within a block, a transactions number is missing
+ *
+ * @param transfers Ordered array of transfers
+ * @param fromBlock Block number indicating start of expected interval
+ * @param toBlock Block number indicating end of expected interval
+ */
+export function doQAETHTransfers(sortedTransfers: ETHTransfer[], fromBlock: number, toBlock: number) {
+  if (fromBlock > toBlock) {
+    throw new Error(`Invalid block range: fromBlock ${fromBlock} is greater than toBlock ${toBlock}`);
+  }
+
+  const groupedTransfers = groupBy(sortedTransfers, (transfer: ETHTransfer) => transfer.blockNumber)
+
+  assertBlocksMatch(groupedTransfers, fromBlock, toBlock);
+
+  for (const key of Object.keys(groupedTransfers)) {
+    assertTransfersWithinBlock(groupedTransfers[key])
+  }
+}
+
+export function mergeSortedArrays<T>(sortedArr1: T[], sortedArr2: T[], comparator: (a: T, b: T) => number = (a, b) =>
+  a < b ? -1 : a > b ? 1 : 0): T[] {
+  const merged: T[] = [];
+  let i = 0, j = 0;
+
+  while (i < sortedArr1.length && j < sortedArr2.length) {
+    if (comparator(sortedArr1[i], sortedArr2[j]) < 0) {
+      merged.push(sortedArr1[i++]);
+    } else {
+      merged.push(sortedArr2[j++]);
+    }
+  }
+
+  return merged.concat(sortedArr1.slice(i), sortedArr2.slice(j));
+}
+
+
diff --git a/src/blockchains/eth/lib/withdrawals_decoder.ts b/src/blockchains/eth/lib/withdrawals_decoder.ts
index 46f6e58..6f46908 100644
--- a/src/blockchains/eth/lib/withdrawals_decoder.ts
+++ b/src/blockchains/eth/lib/withdrawals_decoder.ts
@@ -10,7 +10,7 @@ export class WithdrawalsDecoder {
   }
 
   getBeaconChainWithdrawals(withdrawals: BeaconChainWithdrawal[], blockNumber: number, blockTimestamp: number): ETHTransfer[] {
-    return withdrawals.map((withdrawal) => {
+    return withdrawals.map((withdrawal, index) => {
       const gweiAmount = this.web3Wrapper.gweiToWei(withdrawal.amount);
       return {
         from: constants.ETH_WITHDRAWAL,
@@ -20,6 +20,8 @@ export class WithdrawalsDecoder {
         blockNumber: blockNumber,
         timestamp: blockTimestamp,
         transactionHash: `WITHDRAWAL_${blockNumber}`,
+        transactionPosition: 0,
+        internalTxPosition: index,
         type: 'beacon_withdrawal'
       };
     });
diff --git a/src/blockchains/eth_contracts/lib/transform_create_traces.ts b/src/blockchains/eth_contracts/lib/transform_create_traces.ts
index 8a8739d..5c9ab1d 100644
--- a/src/blockchains/eth_contracts/lib/transform_create_traces.ts
+++ b/src/blockchains/eth_contracts/lib/transform_create_traces.ts
@@ -27,7 +27,9 @@ function constructCreationOutput(parentAddress: string, createTraces: Trace[], b
   ContractCreationTrace[] {
 
   const result: ContractCreationTrace[] = createTraces.map(trace => {
+    assertIsDefined(trace.result, "'result' field is expected in trace on 'create' type")
     assertIsDefined(trace.result.address, "'address' field is expected in trace result on 'create' type")
+    assertIsDefined(trace.transactionHash, "'transactionHash' field is expected in trace result on 'create' type")
 
     const record: ContractCreationTrace = {
       address: trace.result.address,
diff --git a/src/test/eth/decode_transfers.spec.ts b/src/test/eth/decode_transfers.spec.ts
index 20fb5fa..ab4afec 100644
--- a/src/test/eth/decode_transfers.spec.ts
+++ b/src/test/eth/decode_transfers.spec.ts
@@ -3,6 +3,7 @@ process.env.IS_ETH = 'true';
 import { decodeTransferTrace } from '../../blockchains/eth/lib/decode_transfers';
 import { NODE_URL } from '../../blockchains/eth/lib/constants';
 import { Web3Interface, constructWeb3WrapperNoCredentials } from '../../blockchains/eth/lib/web3_wrapper';
+import { ETHTransfer } from '../../blockchains/eth/eth_types';
 
 
 describe('genesis transfers', function () {
@@ -31,7 +32,7 @@ describe('genesis transfers', function () {
     const timestamp = 1000000;
     const result = decodeTransferTrace(suicide_trace, timestamp, web3Wrapper);
 
-    const result_expected = {
+    const result_expected: ETHTransfer = {
       'from': '0xa6c3b7f6520a0ef594fc666d3874ec78c561cdbb',
       'to': '0x245133ea0fb1b77fab5886d7ffb8046dfeff3858',
       'value': 160000000000000000,
@@ -39,6 +40,7 @@ describe('genesis transfers', function () {
       'blockNumber': 711983,
       'timestamp': 1000000,
       'transactionHash': '0xd715da4f846e41be86ea87dc97b186cafea3b50c95d5d9d889ec522b248b207f',
+      'internalTxPosition': 0,
       'transactionPosition': 10,
       'type': 'suicide'
     };
@@ -74,7 +76,7 @@ describe('genesis transfers', function () {
 
     const result = decodeTransferTrace(call_trace, timestamp, web3Wrapper);
 
-    const result_expected = {
+    const result_expected: ETHTransfer = {
       'from': '0x48f2e6e5d0872da169c7f5823d5a2d5ea5f2b5e7',
       'to': '0x7de5aba7de728950c92c57d08e20d4077161f12f',
       'value': 1,
@@ -83,6 +85,7 @@ describe('genesis transfers', function () {
       'timestamp': 1450433505,
       'transactionHash': '0x22f839c82ff455554ec8aa98ee2b9a03d0d5ed4707b46d4a0a217df7d58bda2c',
       'transactionPosition': 10,
+      'internalTxPosition': 0,
       'type': 'call'
     };
 
@@ -112,17 +115,18 @@ describe('genesis transfers', function () {
     const timestamp = 1450433505;
 
     const result = decodeTransferTrace(reward_trace, timestamp, web3Wrapper);
-    const result_expected = {
+    const result_expected: ETHTransfer = {
       'from': 'mining_block',
       'to': '0x2a65aca4d5fc5b5c859090a6c34d164135398226',
       'transactionHash': '0x22f839c82ff455554ec8aa98ee2b9a03d0d5ed4707b46d4a0a217df7d58bda2c',
       'transactionPosition': 10,
+      'internalTxPosition': 0,
       'value': 5000000000000000000,
       'valueExactBase36': '11zk02pzlmwow',
       'blockNumber': 710093,
       'timestamp': 1450433505,
       'type': 'reward'
-    };
+    }
 
     assert.deepStrictEqual(result, result_expected);
   });
@@ -150,7 +154,7 @@ describe('genesis transfers', function () {
     const timestamp = 1450435908;
     const result = decodeTransferTrace(create_trace, timestamp, web3Wrapper);
 
-    const result_expected = {
+    const result_expected: ETHTransfer = {
       'from': '0x245133ea0fb1b77fab5886d7ffb8046dfeff3858',
       'to': '0xa6c3b7f6520a0ef594fc666d3874ec78c561cdbb',
       'value': 1500000000000000000,
@@ -159,8 +163,9 @@ describe('genesis transfers', function () {
       'timestamp': 1450435908,
       'transactionHash': '0x6d39df3c46f19e8ef5e8bb3b81a063a29cb352675a00d66f0dc2117a1799add1',
       'transactionPosition': 11,
+      'internalTxPosition': 0,
       'type': 'create'
-    };
+    }
 
     assert.deepStrictEqual(result, result_expected);
   });
diff --git a/src/test/eth/fees_decoder.spec.ts b/src/test/eth/fees_decoder.spec.ts
index 4e99601..c787c6f 100644
--- a/src/test/eth/fees_decoder.spec.ts
+++ b/src/test/eth/fees_decoder.spec.ts
@@ -1,7 +1,7 @@
 import assert from 'assert';
 import { Web3Interface, constructWeb3WrapperNoCredentials, safeCastToNumber } from '../../blockchains/eth/lib/web3_wrapper';
 import { FeesDecoder } from '../../blockchains/eth/lib/fees_decoder';
-import { ETHBlock, ETHReceipt } from '../../blockchains/eth/eth_types';
+import { ETHBlock, ETHReceipt, ETHTransfer } from '../../blockchains/eth/eth_types';
 import * as constants from '../../blockchains/eth/lib/constants';
 
 /**
@@ -174,7 +174,7 @@ describe('Fees decoder test', function () {
       safeCastToNumber(web3Wrapper.parseHexToNumber(block_json_post_london_zero_priority.number)),
       turnReceiptsToMap(receipts_json_post_london_no_priority), true);
 
-    const expected = [{
+    const expected: ETHTransfer[] = [{
       from: '0xea674fdde714fd979de3edf0f56aa9716b898ec8',
       to: constants.BURN_ADDRESS,
       value: 1049725694283000,
@@ -182,6 +182,8 @@ describe('Fees decoder test', function () {
       blockNumber: 13447057,
       timestamp: 1634631172,
       transactionHash: '0xc8bebc11bbe703cdfb2a1a9599221baf4f19a1e20808866346791799d2dac7a9',
+      transactionPosition: 0,
+      internalTxPosition: 0,
       type: 'fee_burnt'
     }
     ];
@@ -194,12 +196,14 @@ describe('Fees decoder test', function () {
       safeCastToNumber(web3Wrapper.parseHexToNumber(block_json_post_london_with_priority.number)),
       turnReceiptsToMap(receipts_json_post_london_with_priority), true);
 
-    const expected = [{
+    const expected: ETHTransfer[] = [{
       blockNumber: 13447057,
       from: '0x8ae57a027c63fca8070d1bf38622321de8004c67',
       timestamp: 1634631172,
       to: constants.BURN_ADDRESS,
       transactionHash: '0x1e53bf3951f6cb70461df500ec75ed5d88d73bd44d88ca7faabaa4b1e65aec98',
+      transactionPosition: 164,
+      internalTxPosition: 0,
       type: 'fee_burnt',
       value: 3653345337731778,
       valueExactBase36: 'zz03ofi5du'
@@ -212,6 +216,8 @@ describe('Fees decoder test', function () {
       blockNumber: 13447057,
       timestamp: 1634631172,
       transactionHash: '0x1e53bf3951f6cb70461df500ec75ed5d88d73bd44d88ca7faabaa4b1e65aec98',
+      transactionPosition: 164,
+      internalTxPosition: 0,
       type: 'fee'
     }
     ];
@@ -224,12 +230,14 @@ describe('Fees decoder test', function () {
       safeCastToNumber(web3Wrapper.parseHexToNumber(block_json_post_london_old_tx_type.number)),
       turnReceiptsToMap(receipts_json_post_london_old_tx_type), true);
 
-    const expected = [{
+    const expected: ETHTransfer[] = [{
       blockNumber: 13318440,
       from: '0xddfabcdc4d8ffc6d5beaf154f18b778f892a0740',
       timestamp: 1632888074,
       to: constants.BURN_ADDRESS,
       transactionHash: '0xec5b5841e0a425bf69553a0ccecfa58b053a63e30f5fbdd9ecbdee5e9fb0666c',
+      transactionPosition: 97,
+      internalTxPosition: 0,
       type: 'fee_burnt',
       value: 1391883443307000,
       valueExactBase36: 'dpdqfcs260'
@@ -242,6 +250,8 @@ describe('Fees decoder test', function () {
       blockNumber: 13318440,
       timestamp: 1632888074,
       transactionHash: '0xec5b5841e0a425bf69553a0ccecfa58b053a63e30f5fbdd9ecbdee5e9fb0666c',
+      transactionPosition: 97,
+      internalTxPosition: 0,
       type: 'fee'
     }
     ];
@@ -254,7 +264,7 @@ describe('Fees decoder test', function () {
       safeCastToNumber(web3Wrapper.parseHexToNumber(block_json_pre_london.number)),
       turnReceiptsToMap(receipts_json_pre_london), true);
 
-    const expected = [{
+    const expected: ETHTransfer[] = [{
       from: '0x39fa8c5f2793459d6622857e7d9fbb4bd91766d3',
       to: '0x2a65aca4d5fc5b5c859090a6c34d164135398226',
       value: 2354887722000000,
@@ -262,6 +272,8 @@ describe('Fees decoder test', function () {
       blockNumber: 1000000,
       timestamp: 1455404053,
       transactionHash: '0xea1093d492a1dcb1bef708f771a99a96ff05dcab81ca76c31940300177fcf49f',
+      transactionPosition: 0,
+      internalTxPosition: 0,
       type: 'fee'
     }];
 
diff --git a/src/test/eth/fetch_events.spec.ts b/src/test/eth/fetch_events.spec.ts
index cf78082..8ad2fd0 100644
--- a/src/test/eth/fetch_events.spec.ts
+++ b/src/test/eth/fetch_events.spec.ts
@@ -113,6 +113,8 @@ describe('fetch past events', function () {
       blockNumber: 5711193,
       timestamp: 1527814787,
       transactionHash: '0x1a06a3a86d2897741f3ddd774df060a63d626b01197c62015f404e1f007fa04d',
+      transactionPosition: 0,
+      internalTxPosition: 0,
       type: 'fee'
     };
 
@@ -125,6 +127,7 @@ describe('fetch past events', function () {
       timestamp: 1527814787,
       transactionHash: '0x1a06a3a86d2897741f3ddd774df060a63d626b01197c62015f404e1f007fa04d',
       transactionPosition: 0,
+      internalTxPosition: 0,
       type: 'call'
     };
   });
@@ -155,6 +158,8 @@ describe('fetch past events', function () {
       blockNumber: 0,
       timestamp: 1438269973,
       transactionHash: 'GENESIS_000d836201318ec6899a67540690382780743280',
+      transactionPosition: 0,
+      internalTxPosition: 0,
       type: 'genesis'
     };
 
diff --git a/src/test/eth/util.spec.ts b/src/test/eth/util.spec.ts
index da214f5..b478a55 100644
--- a/src/test/eth/util.spec.ts
+++ b/src/test/eth/util.spec.ts
@@ -1,6 +1,6 @@
 import { expect } from 'earl';
 import { cloneDeep } from 'lodash';
-import { transactionOrder, assignInternalTransactionPosition } from "../../blockchains/eth/lib/util"
+import { transactionOrder, assignInternalTransactionPosition, doQAETHTransfers } from "../../blockchains/eth/lib/util"
 import { ETHTransfer } from '../../blockchains/eth/eth_types';
 
 describe('transactionOrder utils', () => {
@@ -74,6 +74,7 @@ describe('transactionOrder utils', () => {
             blockNumber: 1,
             timestamp: 1000,
             transactionHash: "hash",
+            transactionPosition: 0,
             internalTxPosition: 5,
             type: "type"
         }, {
@@ -84,6 +85,7 @@ describe('transactionOrder utils', () => {
             blockNumber: 1,
             timestamp: 2000,
             transactionHash: "hash",
+            transactionPosition: 0,
             internalTxPosition: 2,
             type: "type"
         }
@@ -106,14 +108,15 @@ describe('assignInternalTransactionPosition utils', () => {
             timestamp: 1000,
             transactionHash: "hash",
             transactionPosition: 10,
+            internalTxPosition: 0,
             type: "type"
         }]
         const expected = cloneDeep(transfers)
         expected[0].internalTxPosition = 0
 
-        const result = assignInternalTransactionPosition(transfers)
+        assignInternalTransactionPosition(transfers)
 
-        expect(result).toEqual(expected)
+        expect(transfers).toEqual(expected)
     })
 
     it('zero position is not changed', () => {
@@ -131,8 +134,8 @@ describe('assignInternalTransactionPosition utils', () => {
         }]
         const expected = cloneDeep(transfers)
 
-        const result = assignInternalTransactionPosition(transfers)
-        expect(result).toEqual(expected)
+        assignInternalTransactionPosition(transfers)
+        expect(transfers).toEqual(expected)
     })
 
     it('two different records assigned correctly', () => {
@@ -146,6 +149,7 @@ describe('assignInternalTransactionPosition utils', () => {
             timestamp: 1000,
             transactionHash: "hash1",
             transactionPosition: 1,
+            internalTxPosition: 0,
             type: "type"
         },
         {
@@ -157,14 +161,15 @@ describe('assignInternalTransactionPosition utils', () => {
             timestamp: 1000,
             transactionHash: "hash2",
             transactionPosition: 2,
+            internalTxPosition: 0,
             type: "type"
         }]
         const expected = cloneDeep(transfers)
         expected[0].internalTxPosition = 0
         expected[1].internalTxPosition = 0
 
-        const result = assignInternalTransactionPosition(transfers)
-        expect(result).toEqual(expected)
+        assignInternalTransactionPosition(transfers)
+        expect(transfers).toEqual(expected)
     })
 
     it('two equal records assigned correctly', () => {
@@ -178,6 +183,7 @@ describe('assignInternalTransactionPosition utils', () => {
             timestamp: 1000,
             transactionHash: "hash",
             transactionPosition: 10,
+            internalTxPosition: 0,
             type: "type"
         },
         {
@@ -189,13 +195,116 @@ describe('assignInternalTransactionPosition utils', () => {
             timestamp: 1000,
             transactionHash: "hash",
             transactionPosition: 10,
+            internalTxPosition: 0,
             type: "type"
         }]
         const expected = cloneDeep(transfers)
         expected[0].internalTxPosition = 0
         expected[1].internalTxPosition = 1
 
-        const result = assignInternalTransactionPosition(transfers)
-        expect(result).toEqual(expected)
+        assignInternalTransactionPosition(transfers)
+        expect(transfers).toEqual(expected)
     })
 })
+
+
+describe('doQAETHTransfers', () => {
+    // Helper function to create ETHTransfer objects
+    const createTransfer = (
+        from: string,
+        to: string,
+        value: number,
+        blockNumber: number,
+        transactionHash: string,
+        transactionPosition: number,
+        type: string = 'transfer'
+    ): ETHTransfer => ({
+        from, to, value, valueExactBase36: value.toString(36), blockNumber, timestamp: 1000, transactionHash,
+        transactionPosition, internalTxPosition: 0, type,
+    });
+
+    it('Valid single block with single transaction', () => {
+        const transfers: ETHTransfer[] = [
+            createTransfer('A', 'B', 1, 100, "hash", 0),
+        ]
+
+        expect(() => doQAETHTransfers(transfers, 100, 100)).not.toThrow()
+    })
+
+    it('Valid transfers with multiple blocks and consecutive transactions', () => {
+        const transfers: ETHTransfer[] = [
+            createTransfer('A', 'B', 10, 100, "hash1", 0),
+            createTransfer('C', 'D', 20, 100, "hash2", 1),
+            createTransfer('E', 'F', 10, 101, "hash1", 0),
+            createTransfer('G', 'H', 20, 101, "hash2", 1),
+            createTransfer('I', 'J', 10, 102, "hash1", 0),
+        ]
+
+        expect(() => doQAETHTransfers(transfers, 100, 102)).not.toThrow()
+    });
+
+    it('Multiple transers with same transaction position', () => {
+        const transfers: ETHTransfer[] = [
+            createTransfer('A', 'B', 10, 100, "hash", 0),
+            createTransfer('C', 'D', 20, 100, "hash", 0),
+            createTransfer('E', 'F', 10, 100, "hash", 0),
+        ]
+
+        expect(() => doQAETHTransfers(transfers, 100, 100)).not.toThrow()
+    });
+
+    it('Throws error when a block in the range is missing', () => {
+        const transfers: ETHTransfer[] = [
+            createTransfer('A', 'B', 10, 100, "hash", 0),
+            createTransfer('C', 'D', 20, 102, "hash", 0), // Missing block 101
+            createTransfer('E', 'F', 10, 103, "hash", 0)
+        ]
+
+        expect(() => doQAETHTransfers(transfers, 100, 103)).toThrow('Wrong number of blocks seen. Expected 4 got 3.')
+    })
+
+    it('Throws error when a transaction position is missing within a block', () => {
+        const transfers: ETHTransfer[] = [
+            createTransfer('A', 'B', 10, 100, "hash", 0),
+            // Missing transactionPosition 1 in block 100
+            createTransfer('E', 'F', 20, 100, "hash1", 2),
+            createTransfer('G', 'H', 10, 101, "hash2", 1),
+        ]
+
+        expect(() => doQAETHTransfers(transfers, 100, 101)).toThrow()
+    })
+
+    it('Throws error when transfers array is empty', () => {
+        const transfers: ETHTransfer[] = []
+
+        expect(() => doQAETHTransfers(transfers, 100, 100)).toThrow()
+    })
+
+    it('Throws error when fromBlock is greater than toBlock', () => {
+        const transfers: ETHTransfer[] = [
+            createTransfer('A', 'B', 1, 100, "hash", 0),
+            createTransfer('C', 'D', 2, 101, "hash", 0),
+        ]
+
+        expect(() => doQAETHTransfers(transfers, 102, 100)).toThrow()
+    })
+
+    it('Throws error when the last block is missing', () => {
+        const transfers: ETHTransfer[] = [
+            createTransfer('A', 'B', 1, 100, "hash", 0),
+            createTransfer('C', 'D', 2, 101, "hash", 0),
+            // Missing block 102
+        ];
+
+        expect(() => doQAETHTransfers(transfers, 100, 102)).toThrow()
+    })
+
+    it('Throws error when the data for unexpected blocks is present', () => {
+        const transfers: ETHTransfer[] = [
+            createTransfer('A', 'B', 1, 100, "hash", 0),
+            createTransfer('C', 'D', 2, 101, "hash", 0)
+        ];
+
+        expect(() => doQAETHTransfers(transfers, 102, 103)).toThrow()
+    })
+});
diff --git a/src/test/eth/withdrawals_decoder.spec.ts b/src/test/eth/withdrawals_decoder.spec.ts
index d30dba9..1484eca 100644
--- a/src/test/eth/withdrawals_decoder.spec.ts
+++ b/src/test/eth/withdrawals_decoder.spec.ts
@@ -3,6 +3,7 @@ import assert from 'assert';
 import { WithdrawalsDecoder } from '../../blockchains/eth/lib/withdrawals_decoder';
 import { NODE_URL, ETH_WITHDRAWAL } from '../../blockchains/eth/lib/constants';
 import { Web3Interface, constructWeb3WrapperNoCredentials } from '../../blockchains/eth/lib/web3_wrapper';
+import { ETHTransfer } from '../../blockchains/eth/eth_types';
 
 const web3Wrapper: Web3Interface = constructWeb3WrapperNoCredentials(NODE_URL);
 
@@ -19,7 +20,7 @@ describe('withdrawals decoder test', function () {
 
     const result = decoder.getBeaconChainWithdrawals([withdrawal], 18742200, 1702046471);
 
-    const expected = [{
+    const expected: ETHTransfer[] = [{
       from: ETH_WITHDRAWAL,
       to: withdrawal.address,
       value: 17482528000000000,
@@ -27,6 +28,8 @@ describe('withdrawals decoder test', function () {
       blockNumber: 18742200,
       timestamp: 1702046471,
       transactionHash: 'WITHDRAWAL_18742200',
+      transactionPosition: 0,
+      internalTxPosition: 0,
       type: 'beacon_withdrawal'
     }];
 
diff --git a/src/test/eth/worker.spec.ts b/src/test/eth/worker.spec.ts
index fd52405..ed47b1e 100644
--- a/src/test/eth/worker.spec.ts
+++ b/src/test/eth/worker.spec.ts
@@ -6,17 +6,42 @@ import { ETHBlock, ETHTransfer } from '../../blockchains/eth/eth_types';
 import { expect } from 'earl'
 
 describe('Test worker', function () {
-    let feeResult: ETHTransfer;
+    let feeResultBlock5711191: ETHTransfer;
+    let feeResultBlock5711192: ETHTransfer;
+    let feeResultBlock5711193: ETHTransfer;
     let callResult: ETHTransfer;
     let endOfBlock: EOB;
-    let eobWithPrimaryKey: EOB & { primaryKey: number };
     let worker = new ETHWorker(constants);
     let blockInfos = new Map<number, ETHBlock>()
-    let feeResultWithPrimaryKey: ETHTransfer;
-    let callResultWithPrimaryKey: ETHTransfer;
 
     beforeEach(function () {
-        feeResult = {
+        feeResultBlock5711191 = {
+            from: '0x03b16ab6e23bdbeeab719d8e4c49d63674876253',
+            to: '0x829bd824b016326a401d083b33d092293333a830',
+            value: 14086000000000000,
+            valueExactBase36: '3up2j2e99ts',
+            blockNumber: 5711191,
+            timestamp: 1527814787,
+            transactionHash: '0x1a06a3a86d2897741f3ddd774df060a63d626b01197c62015f404e1f007fa04d',
+            transactionPosition: 0,
+            internalTxPosition: 0,
+            type: 'fee'
+        } satisfies ETHTransfer
+
+        feeResultBlock5711192 = {
+            from: '0x03b16ab6e23bdbeeab719d8e4c49d63674876253',
+            to: '0x829bd824b016326a401d083b33d092293333a830',
+            value: 14086000000000000,
+            valueExactBase36: '3up2j2e99ts',
+            blockNumber: 5711192,
+            timestamp: 1527814787,
+            transactionHash: '0x1a06a3a86d2897741f3ddd774df060a63d626b01197c62015f404e1f007fa04d',
+            transactionPosition: 0,
+            internalTxPosition: 0,
+            type: 'fee'
+        } satisfies ETHTransfer
+
+        feeResultBlock5711193 = {
             from: '0x03b16ab6e23bdbeeab719d8e4c49d63674876253',
             to: '0x829bd824b016326a401d083b33d092293333a830',
             value: 14086000000000000,
@@ -24,8 +49,10 @@ describe('Test worker', function () {
             blockNumber: 5711193,
             timestamp: 1527814787,
             transactionHash: '0x1a06a3a86d2897741f3ddd774df060a63d626b01197c62015f404e1f007fa04d',
+            transactionPosition: 0,
+            internalTxPosition: 0,
             type: 'fee'
-        } satisfies ETHTransfer;
+        } satisfies ETHTransfer
 
         callResult = {
             from: '0x03b16ab6e23bdbeeab719d8e4c49d63674876253',
@@ -36,17 +63,11 @@ describe('Test worker', function () {
             timestamp: 1527814787,
             transactionHash: '0x1a06a3a86d2897741f3ddd774df060a63d626b01197c62015f404e1f007fa04d',
             transactionPosition: 0,
+            internalTxPosition: 0,
             type: 'call'
-        } satisfies ETHTransfer;
-        endOfBlock = endOfBlockEvent(5711193);
-        feeResultWithPrimaryKey = v8.deserialize(v8.serialize(feeResult));
-        feeResultWithPrimaryKey.primaryKey = 1;
+        } satisfies ETHTransfer
 
-        callResultWithPrimaryKey = v8.deserialize(v8.serialize(callResult));
-        callResultWithPrimaryKey.primaryKey = 2;
-
-        eobWithPrimaryKey = v8.deserialize(v8.serialize(endOfBlock));
-        eobWithPrimaryKey.primaryKey = 3;
+        endOfBlock = endOfBlockEvent(5711193);
 
         blockInfos.set(5711191, ethBlockEvent(5711191))
         blockInfos.set(5711192, ethBlockEvent(5711192))
@@ -62,7 +83,7 @@ describe('Test worker', function () {
             return Promise.resolve([[], blockInfos, {}]);
         };
         worker.transformPastEvents = function () {
-            return [feeResult, callResult];
+            return [feeResultBlock5711191, feeResultBlock5711192, feeResultBlock5711193, callResult];
         };
 
         const result = await worker.work();
@@ -72,8 +93,8 @@ describe('Test worker', function () {
         // so there should be 3 EOB
         const blocks = result.map((value) => value.blockNumber);
         const types = result.map((value) => value.type);
-        expect(blocks).toEqual([5711191, 5711192, 5711193, 5711193, 5711193]);
-        expect(types).toEqual(["EOB", "EOB", "fee", "call", "EOB"]);
+        expect(blocks).toEqual([5711191, 5711191, 5711192, 5711192, 5711193, 5711193, 5711193]);
+        expect(types).toEqual(["fee", "EOB", "fee", "EOB", "fee", "call", "EOB"]);
     })
 
 });
@@ -103,6 +124,7 @@ function endOfBlockEvent(blockNumber: number): EOB {
         timestamp: 1438271100,
         transactionHash: "0x0000000000000000000000000000000000000000",
         transactionPosition: 2147483647,
+        internalTxPosition: 0,
         type: "EOB"
     };
 }