diff --git a/lib/build/amodro-trace/lib/parse.js b/lib/build/amodro-trace/lib/parse.js
index 078380da7..10861808c 100644
--- a/lib/build/amodro-trace/lib/parse.js
+++ b/lib/build/amodro-trace/lib/parse.js
@@ -7,7 +7,7 @@ var define = function(ary, fn) {
 
 /*jslint plusplus: true */
 /*global define: false */
-define(['esprima', './lang'], function (esprima, lang) {
+define(['meriyah', './lang'], function (meriyah, lang) {
     'use strict';
 
     function arrayToString(ary) {
@@ -30,7 +30,7 @@ define(['esprima', './lang'], function (esprima, lang) {
         mixin = lang.mixin,
         hasProp = lang.hasProp;
 
-    //From an esprima example for traversing its ast.
+    //From an meriyah example for traversing its ast.
     function traverse(object, visitor) {
         var child;
 
@@ -131,7 +131,7 @@ define(['esprima', './lang'], function (esprima, lang) {
             result = '',
             moduleList = [],
             needsDefine = true,
-            astRoot = esprima.parse(fileContents);
+            astRoot = meriyah.parseScript(fileContents, {next: true, webcompat: true});
 
         parse.recurse(astRoot, function (callName, config, name, deps, node, factoryIdentifier, fnExpScope) {
             if (!deps) {
@@ -296,85 +296,6 @@ define(['esprima', './lang'], function (esprima, lang) {
         }
     };
 
-    /**
-     * Determines if the file defines the require/define module API.
-     * Specifically, it looks for the `define.amd = ` expression.
-     * @param {String} fileName
-     * @param {String} fileContents
-     * @returns {Boolean}
-     */
-    parse.definesRequire = function (fileName, fileContents) {
-        var foundDefine = false,
-            foundDefineAmd = false;
-
-        traverse(esprima.parse(fileContents), function (node) {
-            // Look for a top level declaration of a define, like
-            // var requirejs, require, define, off Program body.
-            if (node.type === 'Program' && node.body && node.body.length) {
-                foundDefine = node.body.some(function(bodyNode) {
-                    // var define
-                    if (bodyNode.type === 'VariableDeclaration') {
-                        var decls = bodyNode.declarations;
-                        if (decls) {
-                            var hasVarDefine = decls.some(function(declNode) {
-                                return (declNode.type === 'VariableDeclarator' &&
-                                        declNode.id &&
-                                        declNode.id.type === 'Identifier' &&
-                                        declNode.id.name === 'define');
-                            });
-                            if (hasVarDefine) {
-                                return true;
-                            }
-                        }
-                    }
-
-                    // function define() {}
-                    if (bodyNode.type === 'FunctionDeclaration' &&
-                        bodyNode.id &&
-                        bodyNode.id.type === 'Identifier' &&
-                        bodyNode.id.name === 'define') {
-                        return true;
-                    }
-
-
-
-
-
-
-                });
-            }
-
-            // Need define variable found first, before detecting define.amd.
-            if (foundDefine && parse.hasDefineAmd(node)) {
-                foundDefineAmd = true;
-
-                //Stop traversal
-                return false;
-            }
-        });
-
-        return foundDefine && foundDefineAmd;
-    };
-
-    /**
-     * Finds require("") calls inside a CommonJS anonymous module wrapped in a
-     * define(function(require, exports, module){}) wrapper. These dependencies
-     * will be added to a modified define() call that lists the dependencies
-     * on the outside of the function.
-     * @param {String} fileName
-     * @param {String|Object} fileContents: a string of contents, or an already
-     * parsed AST tree.
-     * @returns {Array} an array of module names that are dependencies. Always
-     * returns an array, but could be of length zero.
-     */
-    parse.getAnonDeps = function (fileName, fileContents) {
-        var astRoot = typeof fileContents === 'string' ?
-                      esprima.parse(fileContents) : fileContents,
-            defFunc = this.findAnonDefineFactory(astRoot);
-
-        return parse.getAnonDepsFromNode(defFunc);
-    };
-
     /**
      * Finds require("") calls inside a CommonJS anonymous module wrapped
      * in a define function, given an AST node for the definition function.
@@ -457,8 +378,10 @@ define(['esprima', './lang'], function (esprima, lang) {
         /*jslint evil: true */
         var jsConfig, foundConfig, stringData, foundRange, quote, quoteMatch,
             quoteRegExp = /(:\s|\[\s*)(['"])/,
-            astRoot = esprima.parse(fileContents, {
-                loc: true
+            astRoot = meriyah.parseScript(fileContents, {
+                loc: true,
+                next: true,
+                webcompat: true
             });
 
         traverse(astRoot, function (node) {
@@ -514,54 +437,6 @@ define(['esprima', './lang'], function (esprima, lang) {
         }
     };
 
-    /**
-     * Renames require/requirejs/define calls to be ns + '.' + require/requirejs/define
-     * Does *not* do .config calls though. See pragma.namespace for the complete
-     * set of namespace transforms. This function is used because require calls
-     * inside a define() call should not be renamed, so a simple regexp is not
-     * good enough.
-     * @param  {String} fileContents the contents to transform.
-     * @param  {String} ns the namespace, *not* including trailing dot.
-     * @return {String} the fileContents with the namespace applied
-     */
-    parse.renameNamespace = function (fileContents, ns) {
-        var lines,
-            locs = [],
-            astRoot = esprima.parse(fileContents, {
-                loc: true
-            });
-
-        parse.recurse(astRoot, function (callName, config, name, deps, node) {
-            locs.push(node.loc);
-            //Do not recurse into define functions, they should be using
-            //local defines.
-            return callName !== 'define';
-        }, {});
-
-        if (locs.length) {
-            lines = fileContents.split('\n');
-
-            //Go backwards through the found locs, adding in the namespace name
-            //in front.
-            locs.reverse();
-            locs.forEach(function (loc) {
-                var startIndex = loc.start.column,
-                //start.line is 1-based, not 0 based.
-                lineIndex = loc.start.line - 1,
-                line = lines[lineIndex];
-
-                lines[lineIndex] = line.substring(0, startIndex) +
-                                   ns + '.' +
-                                   line.substring(startIndex,
-                                                      line.length);
-            });
-
-            fileContents = lines.join('\n');
-        }
-
-        return fileContents;
-    };
-
     /**
      * Finds all dependencies specified in dependency arrays and inside
      * simplified commonjs wrappers.
@@ -577,7 +452,7 @@ define(['esprima', './lang'], function (esprima, lang) {
         if (fileContents && fileContents.type) {
           astRoot = fileContents
         } else {
-          astRoot = esprima.parse(fileContents);
+          astRoot = meriyah.parseScript(fileContents, {next: true, webcompat: true});
         }
 
         parse.recurse(astRoot, function (callName, config, name, deps) {
@@ -596,7 +471,7 @@ define(['esprima', './lang'], function (esprima, lang) {
     parse.findCjsDependencies = function (fileName, fileContents) {
         var dependencies = [];
 
-        traverse(esprima.parse(fileContents), function (node) {
+        traverse(meriyah.parseScript(fileContents, {next: true, webcompat: true}), function (node) {
             var arg;
 
             if (node && node.type === 'CallExpression' && node.callee &&
@@ -668,53 +543,6 @@ define(['esprima', './lang'], function (esprima, lang) {
             node.callee.name === 'define';
     };
 
-    /**
-     * If there is a named define in the file, returns the name. Does not
-     * scan for mulitple names, just the first one.
-     */
-    parse.getNamedDefine = function (fileContents) {
-        var name;
-        traverse(esprima.parse(fileContents), function (node) {
-            if (node && node.type === 'CallExpression' && node.callee &&
-            node.callee.type === 'Identifier' &&
-            node.callee.name === 'define' &&
-            node[argPropName] && node[argPropName][0] &&
-            node[argPropName][0].type === 'Literal') {
-                name = node[argPropName][0].value;
-                return false;
-            }
-        });
-
-        return name;
-    };
-
-    /**
-     * Finds all the named define module IDs in a file.
-     */
-    parse.getAllNamedDefines = function (fileContents, excludeMap) {
-        var names = [];
-        parse.recurse(esprima.parse(fileContents),
-        function (callName, config, name, deps, node, factoryIdentifier, fnExpScope) {
-            if (callName === 'define' && name) {
-                if (!excludeMap.hasOwnProperty(name)) {
-                    names.push(name);
-                }
-            }
-
-            //If a UMD definition that points to a factory that is an Identifier,
-            //indicate processing should not traverse inside the UMD definition.
-            if (callName === 'define' && factoryIdentifier && hasProp(fnExpScope, factoryIdentifier)) {
-                return factoryIdentifier;
-            }
-
-            //If define was found, no need to dive deeper, unless
-            //the config explicitly wants to dig deeper.
-            return true;
-        }, {});
-
-        return names;
-    };
-
     /**
      * Determines if define(), require({}|[]) or requirejs was called in the
      * file. Also finds out if define() is declared and if define.amd is called.
@@ -722,7 +550,7 @@ define(['esprima', './lang'], function (esprima, lang) {
     parse.usesAmdOrRequireJs = function (fileName, fileContents) {
         var uses;
 
-        traverse(esprima.parse(fileContents), function (node) {
+        traverse(meriyah.parseScript(fileContents, {next: true, webcompat: true}), function (node) {
             var type, callName, arg;
 
             if (parse.hasDefDefine(node)) {
@@ -764,7 +592,7 @@ define(['esprima', './lang'], function (esprima, lang) {
             assignsExports = false;
 
 
-        traverse(esprima.parse(fileContents), function (node) {
+        traverse(meriyah.parseScript(fileContents, {next: true, webcompat: true}), function (node) {
             var type,
                 // modified to fix a bug on (true || exports.name = {})
                 // https://github.com/requirejs/r.js/issues/980
@@ -980,7 +808,7 @@ define(['esprima', './lang'], function (esprima, lang) {
     /**
      * Converts an AST node into a JS source string by extracting
      * the node's location from the given contents string. Assumes
-     * esprima.parse() with loc was done.
+     * meriyah.parseScript() with loc was done.
      * @param {String} contents
      * @param {Object} node
      * @returns {String} a JS source string.
@@ -1015,75 +843,5 @@ define(['esprima', './lang'], function (esprima, lang) {
         };
     };
 
-    /**
-     * Extracts license comments from JS text.
-     * @param {String} fileName
-     * @param {String} contents
-     * @returns {String} a string of license comments.
-     */
-    parse.getLicenseComments = function (fileName, contents) {
-        var commentNode, refNode, subNode, value, i, j,
-            //xpconnect's Reflect does not support comment or range, but
-            //prefer continued operation vs strict parity of operation,
-            //as license comments can be expressed in other ways, like
-            //via wrap args, or linked via sourcemaps.
-            ast = esprima.parse(contents, {
-                comment: true,
-                range: true
-            }),
-            result = '',
-            existsMap = {},
-            lineEnd = contents.indexOf('\r') === -1 ? '\n' : '\r\n';
-
-        if (ast.comments) {
-            for (i = 0; i < ast.comments.length; i++) {
-                commentNode = ast.comments[i];
-
-                if (commentNode.type === 'Line') {
-                    value = '//' + commentNode.value + lineEnd;
-                    refNode = commentNode;
-
-                    if (i + 1 >= ast.comments.length) {
-                        value += lineEnd;
-                    } else {
-                        //Look for immediately adjacent single line comments
-                        //since it could from a multiple line comment made out
-                        //of single line comments. Like this comment.
-                        for (j = i + 1; j < ast.comments.length; j++) {
-                            subNode = ast.comments[j];
-                            if (subNode.type === 'Line' &&
-                                    subNode.range[0] === refNode.range[1] + 1) {
-                                //Adjacent single line comment. Collect it.
-                                value += '//' + subNode.value + lineEnd;
-                                refNode = subNode;
-                            } else {
-                                //No more single line comment blocks. Break out
-                                //and continue outer looping.
-                                break;
-                            }
-                        }
-                        value += lineEnd;
-                        i = j - 1;
-                    }
-                } else {
-                    value = '/*' + commentNode.value + '*/' + lineEnd + lineEnd;
-                }
-
-                if (!existsMap[value] && (value.indexOf('license') !== -1 ||
-                        (commentNode.type === 'Block' &&
-                            value.indexOf('/*!') === 0) ||
-                        value.indexOf('opyright') !== -1 ||
-                        value.indexOf('(c)') !== -1)) {
-
-                    result += value;
-                    existsMap[value] = true;
-                }
-
-            }
-        }
-
-        return result;
-    };
-
     return parse;
 });
diff --git a/lib/build/amodro-trace/lib/transform.js b/lib/build/amodro-trace/lib/transform.js
index 6a6b0d264..d81204413 100644
--- a/lib/build/amodro-trace/lib/transform.js
+++ b/lib/build/amodro-trace/lib/transform.js
@@ -13,8 +13,8 @@ var define = function(ary, fn) {
 
 /*global define */
 
-define([ 'esprima', './parse', './lang'],
-function (esprima, parse, lang) {
+define([ 'meriyah', './parse', './lang'],
+function (meriyah, parse, lang) {
     'use strict';
     var transform,
         jsExtRegExp = /\.js$/g,
@@ -51,8 +51,10 @@ function (esprima, parse, lang) {
                 };
 
             try {
-                astRoot = esprima.parse(contents, {
-                    loc: true
+                astRoot = meriyah.parseScript(contents, {
+                    loc: true,
+                    next: true,
+                    webcompat: true
                 });
             } catch (e) {
                 var logger = options.logger;
diff --git a/lib/build/amodro-trace/write/replace.js b/lib/build/amodro-trace/write/replace.js
index 180eda093..73afd3dde 100644
--- a/lib/build/amodro-trace/write/replace.js
+++ b/lib/build/amodro-trace/write/replace.js
@@ -4,7 +4,7 @@
 
 // and also dep string cleanup
 // remove tailing '/', '.js'
-const esprima = require('esprima');
+const meriyah = require('meriyah');
 const astMatcher = require('../../ast-matcher').astMatcher;
 // it is definitely a named AMD module at this stage
 var amdDep = astMatcher('define(__str, [__anl_deps], __any)');
@@ -46,7 +46,7 @@ module.exports = function stubs(options) {
     };
 
     // need node location
-    const parsed = esprima.parse(contents, {range: true});
+    const parsed = meriyah.parseScript(contents, {ranges: true, next: true, webcompat: true});
 
     if (isUMD(parsed) || isUMD2(parsed)) {
       // Skip lib in umd format, because browersify umd build could
diff --git a/lib/build/ast-matcher.js b/lib/build/ast-matcher.js
index 30611475a..a12765646 100644
--- a/lib/build/ast-matcher.js
+++ b/lib/build/ast-matcher.js
@@ -1,4 +1,4 @@
-const esprima = require('esprima');
+const meriyah = require('meriyah');
 
 const STOP = false;
 const SKIP_BRANCH = 1;
@@ -6,7 +6,7 @@ const SKIP_BRANCH = 1;
 // ignore position info, and raw
 const IGNORED_KEYS = ['start', 'end', 'loc', 'location', 'locations', 'line', 'column', 'range', 'ranges', 'raw'];
 
-// From an esprima example for traversing its ast.
+// From an meriyah example for traversing its ast.
 // modified to support branch skip.
 function traverse(object, visitor) {
   let child;
@@ -60,7 +60,7 @@ function matchTerm(pattern) {
 }
 
 /**
- * Extract info from a partial esprima syntax tree, see astMatcher for pattern format
+ * Extract info from a partial meriyah syntax tree, see astMatcher for pattern format
  * @param pattern The pattern used on matching
  * @param part The target partial syntax tree
  * @return Returns named matches, or false.
@@ -172,19 +172,19 @@ exports.extract = function(pattern, part) {
 };
 
 /**
- * Compile a pattern into esprima syntax tree
- * @param pattern The pattern used on matching, can be a string or esprima node
- * @return Returns an esprima node to be used as pattern in extract(pattern, part)
+ * Compile a pattern into meriyah syntax tree
+ * @param pattern The pattern used on matching, can be a string or meriyah node
+ * @return Returns an meriyah node to be used as pattern in extract(pattern, part)
  */
 exports.compilePattern = function(pattern) {
-  // pass esprima syntax tree obj
+  // pass meriyah syntax tree obj
   if (pattern && pattern.type) return pattern;
 
   if (typeof pattern !== 'string') {
-    throw new Error('input pattern is neither a string nor an esprima node.');
+    throw new Error('input pattern is neither a string nor an meriyah node.');
   }
 
-  let exp = esprima.parse(pattern);
+  let exp = meriyah.parseScript(pattern, {next: true, webcompat: true});
 
   if (exp.type !== 'Program' || !exp.body) {
     throw new Error(`Not a valid expression:  "${pattern}".`);
@@ -207,13 +207,13 @@ exports.compilePattern = function(pattern) {
 function ensureParsed(codeOrNode) {
   // bypass parsed node
   if (codeOrNode && codeOrNode.type) return codeOrNode;
-  return esprima.parse(codeOrNode);
+  return meriyah.parseScript(codeOrNode, {next: true, webcompat: true});
 }
 
 /**
  * Pattern matching using AST on JavaScript source code
  * @param pattern The pattern to be matched
- * @return Returns a function that takes source code string (or esprima syntax tree) as input, produces matched result or undefined.
+ * @return Returns a function that takes source code string (or meriyah syntax tree) as input, produces matched result or undefined.
  *
  * __any       matches any single node, but no extract
  * __anl       matches array of nodes, but no extract
@@ -268,7 +268,7 @@ exports.astMatcher = function(pattern) {
 /**
  * Dependency search for dummies, this is a high level api to simplify the usage of astMatcher
  * @param arguments Multiple patterns to match, instead of using __str_/__arr_, use __dep and __deps to match string or partial string array.
- * @return Returns a function that takes source code string (or esprima syntax tree) as input, produces an array of string matched, or empty array.
+ * @return Returns a function that takes source code string (or meriyah syntax tree) as input, produces an array of string matched, or empty array.
  *
  * Usage:
  *   let f = jsDepFinder('a(__dep)', '__any.globalResources([__deps])');
diff --git a/lib/build/find-deps.js b/lib/build/find-deps.js
index 27df45343..2d2ef198b 100644
--- a/lib/build/find-deps.js
+++ b/lib/build/find-deps.js
@@ -1,4 +1,4 @@
-const esprima = require('esprima');
+const meriyah = require('meriyah');
 const parse = require('./amodro-trace/lib/parse');
 const am = require('./ast-matcher');
 const jsDepFinder = am.jsDepFinder;
@@ -231,7 +231,7 @@ exports.findJsDeps = function(filename, contents, loaderType = 'require') {
 
   // for all following static analysis,
   // only parse once for efficiency
-  let parsed = esprima.parse(contents);
+  let parsed = meriyah.parseScript(contents, {next: true, webcompat: true});
 
   add(parse.findDependencies(filename, parsed));
   // clear commonjs wrapper deps
diff --git a/package.json b/package.json
index de018f1f3..af65846ce 100644
--- a/package.json
+++ b/package.json
@@ -59,7 +59,6 @@
     "del": "^6.0.0",
     "domain-browser": "^4.19.0",
     "enquirer": "^2.3.6",
-    "esprima": "^4.0.1",
     "events": "^3.3.0",
     "fs-browser-stub": "^1.0.1",
     "gulp": "^4.0.2",
@@ -67,6 +66,7 @@
     "https-browserify": "^1.0.0",
     "lodash": "^4.17.21",
     "map-stream": "0.0.7",
+    "meriyah": "^4.1.5",
     "minimatch": "^3.0.4",
     "npm-which": "^3.0.1",
     "os-browserify": "^0.3.0",
diff --git a/spec/lib/build/ast-matcher.spec.js b/spec/lib/build/ast-matcher.spec.js
index 5534d92fe..cc9671000 100644
--- a/spec/lib/build/ast-matcher.spec.js
+++ b/spec/lib/build/ast-matcher.spec.js
@@ -1,4 +1,4 @@
-const esprima = require('esprima');
+const meriyah = require('meriyah');
 
 const astm = require('../../../lib/build/ast-matcher');
 const extract = astm.extract;
@@ -11,8 +11,8 @@ const extractTest = function(pattern, part) {
 };
 
 describe('compilePattern', () => {
-  it('bypass esprima node', () => {
-    let node = esprima.parse('a = 1');
+  it('bypass meriyah node', () => {
+    let node = meriyah.parseScript('a = 1');
     expect(compilePattern(node)).toBe(node);
   });
 
@@ -60,16 +60,13 @@ describe('extract', () => {
     expect(Object.keys(r)).toEqual(['a']);
     expect(r.a.type).toBe('Literal');
     expect(r.a.value).toBe('foo');
-    expect(r.a.raw).toBe('"foo"');
 
     r = extractTest('a(__any_a,__any_b)', 'a("foo", "bar")');
     expect(Object.keys(r).sort()).toEqual(['a', 'b']);
     expect(r.a.type).toBe('Literal');
     expect(r.a.value).toBe('foo');
-    expect(r.a.raw).toBe('"foo"');
     expect(r.b.type).toBe('Literal');
     expect(r.b.value).toBe('bar');
-    expect(r.b.raw).toBe('"bar"');
   });
 
   it('__anl matches nodes array, but no extract', () => {
@@ -208,7 +205,7 @@ describe('matcher built by astMatcher', () => {
   it('accepts both string input or node input', () => {
     let m = astMatcher('a(__str_foo)');
     expect(m('a("foo")').length).toBe(1);
-    expect(m(esprima.parse('a("foo")')).length).toBe(1);
+    expect(m(meriyah.parseScript('a("foo")')).length).toBe(1);
   });
 
   it('rejects unknown input', () => {
@@ -281,9 +278,9 @@ describe('jsDepFinder', () => {
     expect(f('a("a"); b("b"); b.a("c")')).toEqual(['a']);
   });
 
-  it('finds matching dep, accepts esprima node as input', () => {
+  it('finds matching dep, accepts meriyah node as input', () => {
     let f = jsDepFinder('a(__dep)');
-    expect(f(esprima.parse('a("a"); b("b"); b.a("c")'))).toEqual(['a']);
+    expect(f(meriyah.parseScript('a("a"); b("b"); b.a("c")'))).toEqual(['a']);
   });
 
   it('finds matching dep by matching length', () => {