diff --git a/back-end/pyworkflow/pyworkflow/node.py b/back-end/pyworkflow/pyworkflow/node.py
index 0a3bc20..898fe1c 100644
--- a/back-end/pyworkflow/pyworkflow/node.py
+++ b/back-end/pyworkflow/pyworkflow/node.py
@@ -54,6 +54,7 @@ def get_execution_options(self, workflow, flow_nodes):
 
             if key in flow_nodes:
                 replacement_value = flow_nodes[key].get_replacement_value()
+                option.set_value(replacement_value)
             else:
                 replacement_value = option.get_value()
 
diff --git a/back-end/pyworkflow/pyworkflow/nodes/flow_control/integer_input.py b/back-end/pyworkflow/pyworkflow/nodes/flow_control/integer_input.py
index 086eb89..0ecb0cf 100644
--- a/back-end/pyworkflow/pyworkflow/nodes/flow_control/integer_input.py
+++ b/back-end/pyworkflow/pyworkflow/nodes/flow_control/integer_input.py
@@ -8,8 +8,8 @@ class IntegerNode(FlowNode):
     Allows for Strings to replace 'string' fields in Nodes
     """
     name = "Integer Input"
-    num_in = 1
-    num_out = 1
+    num_in = 0
+    num_out = 0
     color = 'purple'
 
     OPTIONS = {
diff --git a/back-end/pyworkflow/pyworkflow/nodes/flow_control/string_input.py b/back-end/pyworkflow/pyworkflow/nodes/flow_control/string_input.py
index eaade18..81a785b 100644
--- a/back-end/pyworkflow/pyworkflow/nodes/flow_control/string_input.py
+++ b/back-end/pyworkflow/pyworkflow/nodes/flow_control/string_input.py
@@ -8,8 +8,8 @@ class StringNode(FlowNode):
     Allows for Strings to replace 'string' fields in Nodes
     """
     name = "String Input"
-    num_in = 1
-    num_out = 1
+    num_in = 0
+    num_out = 0
     color = 'purple'
 
     OPTIONS = {
diff --git a/back-end/pyworkflow/pyworkflow/workflow.py b/back-end/pyworkflow/pyworkflow/workflow.py
index 6d29a07..a9515a8 100644
--- a/back-end/pyworkflow/pyworkflow/workflow.py
+++ b/back-end/pyworkflow/pyworkflow/workflow.py
@@ -172,7 +172,7 @@ def get_all_flow_var_options(self, node_id):
         for predecessor_id in self.get_node_predecessors(node_id):
             node = self.get_node(predecessor_id)
 
-            if node.node_type == 'FlowNode':
+            if node.node_type == 'flow_control':
                 flow_variables.append(node.to_json())
 
         return flow_variables
@@ -314,7 +314,7 @@ def execute(self, node_id):
         except NodeException as e:
             raise e
 
-        if node_to_execute.data is None:
+        if node_to_execute.data is None and node_to_execute.node_type != "flow_control":
             raise WorkflowException('execute', 'There was a problem saving node output.')
 
         return node_to_execute
@@ -384,7 +384,7 @@ def load_input_data(self, node_id):
                 if node_to_retrieve is None:
                     raise WorkflowException('retrieve node data', 'The workflow does not contain node %s' % predecessor_id)
 
-                if node_to_retrieve.node_type != 'FlowNode':
+                if node_to_retrieve.node_type != 'flow_control':
                     input_data.append(self.retrieve_node_data(node_to_retrieve))
 
             except WorkflowException:
diff --git a/front-end/src/API.js b/front-end/src/API.js
index a61e6e8..a184885 100644
--- a/front-end/src/API.js
+++ b/front-end/src/API.js
@@ -26,6 +26,16 @@ function fetchWrapper(endpoint, options = {}) {
 }
 
 
+/**
+ * Retrieve node info from server side workflow
+ * @param {string} nodeId - ID of node to retrieve
+ * @returns {Promise<Object>} - server response (node info and flow variables)
+ */
+export async function getNode(nodeId) {
+    return fetchWrapper(`/node/${nodeId}`);
+}
+
+
 /**
  * Add node to server-side workflow
  * @param {CustomNodeModel} node - JS node to add
diff --git a/front-end/src/components/CustomNode/CustomNodeModel.js b/front-end/src/components/CustomNode/CustomNodeModel.js
index c382e3a..a3d05ff 100644
--- a/front-end/src/components/CustomNode/CustomNodeModel.js
+++ b/front-end/src/components/CustomNode/CustomNodeModel.js
@@ -13,6 +13,24 @@ export default class CustomNodeModel extends NodeModel {
         this.configParams = options.option_types;
         this.options.status = options.status || "unconfigured";
 
+        // add flow control input port
+        this.addPort(
+            new VPPortModel({
+                in: true,
+                type: 'vp-port',
+                name: 'flow-in'
+            })
+        );
+        // if flow node, add flow control output port
+        if (this.options.node_type === "flow_control") {
+            this.addPort(
+                new VPPortModel({
+                    in: false,
+                    type: 'vp-port',
+                    name: 'flow-out'
+                })
+            );
+        }
         const nIn = options.num_in === undefined ? 1 : options.num_in;
         const nOut = options.num_out === undefined ? 1 : options.num_out;
         // setup in and out ports
diff --git a/front-end/src/components/CustomNode/CustomNodeWidget.js b/front-end/src/components/CustomNode/CustomNodeWidget.js
index a5a8e2b..6bc38eb 100644
--- a/front-end/src/components/CustomNode/CustomNodeWidget.js
+++ b/front-end/src/components/CustomNode/CustomNodeWidget.js
@@ -47,7 +47,10 @@ export default class CustomNodeWidget extends React.Component {
 
     render() {
         const engine = this.props.engine;
-        const ports = _.values(this.props.node.getPorts());
+        const allPorts = _.values(this.props.node.getPorts());
+        const ports = allPorts.filter(p => !p.options.name.includes("flow"));
+        const flowInPort = allPorts.find(p => p.options.name === "flow-in");
+        const flowOutPort = allPorts.find(p => p.options.name === "flow-out");
         // group ports by type (in/out)
         const sortedPorts = _.groupBy(ports, p => p.options.in === true ? "in" : "out");
         // create PortWidget array for each type
@@ -55,11 +58,19 @@ export default class CustomNodeWidget extends React.Component {
         for (let portType in sortedPorts) {
             portWidgets[portType] = sortedPorts[portType].map(port =>
                 <PortWidget engine={engine} port={port} key={port.getID()}>
-                        <div className="triangle-port" />
+                    <div className="triangle-port" />
                 </PortWidget>
             );
         }
 
+        const flowPortWidgets = [flowInPort, flowOutPort].filter(p => p).map(port =>
+            <PortWidget engine={engine} port={port} key={port.getID()}
+                        className={`flow-port-div flow-port-div-${port.options.in ? "in" : "out"}`}>
+                <div className="flow-port" />
+            </PortWidget>
+        );
+
+
         let graphView;
         let width = 40;
         if (this.props.node.options.node_type !== "flow_control") {
@@ -75,19 +86,23 @@ export default class CustomNodeWidget extends React.Component {
             <div className="custom-node-wrapper">
                 <div className="custom-node-name">{this.props.node.options.name}</div>
                 <div className="custom-node" style={{ borderColor: this.props.node.options.color, width: width }}>
-                    <div className="custom-node-configure" onClick={this.toggleConfig}>{String.fromCharCode(this.icon)}</div>
-                    <NodeConfig node={this.props.node}
-                        globals={this.props.engine.model.globals || []}
-                        show={this.state.showConfig}
-                        toggleShow={this.toggleConfig}
-                        onDelete={this.handleDelete}
-                        onSubmit={this.acceptConfiguration} />
-                    {graphView}
-                    <GraphView node={this.props.node}
-                        show={this.state.showGraph}
-                        toggleShow={this.toggleGraph}
-                        onDelete={this.handleDelete}
-                        onSubmit={this.acceptConfiguration} />
+                    <div className="custom-node-icons">
+                        <div className="custom-node-configure" onClick={this.toggleConfig}>
+                            {String.fromCharCode(this.icon)}
+                        </div>
+                        <NodeConfig node={this.props.node}
+                            show={this.state.showConfig}
+                            toggleShow={this.toggleConfig}
+                            onDelete={this.handleDelete}
+                            onSubmit={this.acceptConfiguration} />
+                        {graphView}
+                        <GraphView node={this.props.node}
+                            show={this.state.showGraph}
+                            toggleShow={this.toggleGraph}
+                            onDelete={this.handleDelete}
+                            onSubmit={this.acceptConfiguration} />
+                    </div>
+                    {flowPortWidgets}
                     <div className="port-col port-col-in">
                         { portWidgets["in"] }
                     </div>
diff --git a/front-end/src/components/CustomNode/NodeConfig.js b/front-end/src/components/CustomNode/NodeConfig.js
index 67c8f94..a30df87 100644
--- a/front-end/src/components/CustomNode/NodeConfig.js
+++ b/front-end/src/components/CustomNode/NodeConfig.js
@@ -12,13 +12,25 @@ export default class NodeConfig extends React.Component {
         this.state = {
             disabled: false,
             data: {},
-            flowData: {}
+            flowData: {},
+            flowNodes: []
         };
         this.updateData = this.updateData.bind(this);
         this.handleDelete = this.handleDelete.bind(this);
         this.handleSubmit = this.handleSubmit.bind(this);
     }
 
+    getFlowNodes() {
+        if (!this.props.node) return;
+        API.getNode(this.props.node.options.id)
+            .then(node => this.setState({flowNodes: node.flow_variables}))
+            .catch(err => console.log(err));
+    }
+
+    componentDidUpdate(prevProps) {
+        if (!prevProps.show && this.props.show) this.getFlowNodes();
+    }
+
     // callback to update form data in state;
     // resulting state will be sent to node config callback
     updateData(key, value, flow = false) {
@@ -82,7 +94,7 @@ export default class NodeConfig extends React.Component {
                                          value={this.props.node.config[key]}
                                          flowValue={this.props.node.options.option_replace ?
                                             this.props.node.options.option_replace[key] : null}
-                                         globals={this.props.globals}
+                                         flowNodes={this.state.flowNodes}
                                          disableFunc={(v) => this.setState({disabled: v})}/>
                         )}
                         <Form.Group>
@@ -149,7 +161,7 @@ function OptionInput(props) {
     }
 
     const hideFlow = props.node.options.is_global
-                        || props.type === "file" || props.globals.length === 0
+                        || props.type === "file" || props.flowNodes.length === 0;
     return (
         <Form.Group>
             <Form.Label>{props.label}</Form.Label>
@@ -159,7 +171,7 @@ function OptionInput(props) {
                 {hideFlow ? null :
                     <FlowVariableOverride keyName={props.keyName}
                                           flowValue={props.flowValue || {}}
-                                          flowNodes={props.globals || []}
+                                          flowNodes={props.flowNodes || []}
                                           checked={isFlow}
                                           onFlowCheck={handleFlowCheck}
                                           onChange={handleFlowVariable} />
@@ -290,7 +302,7 @@ function FlowVariableOverride(props) {
 
     const handleSelect = (event) => {
         const uuid = event.target.value;
-        const flow = props.flowNodes.find(d => d.id === uuid);
+        const flow = props.flowNodes.find(d => d.node_id === uuid);
         const obj = {
             node_id: uuid,
             is_global: flow.is_global
@@ -308,9 +320,9 @@ function FlowVariableOverride(props) {
                 <Form.Control as="select" name={props.keyName} onChange={handleSelect}
                               value={props.flowValue.node_id}>
                     <option/>
-                    {props.flowNodes.map(gfv =>
-                        <option  key={gfv.id} value={gfv.id}>
-                            {gfv.options.var_name}
+                    {props.flowNodes.map(fv =>
+                        <option  key={fv.node_id} value={fv.node_id}>
+                            {fv.options ? fv.options.var_name : fv.option_values.var_name}
                         </option>
                     )}
                 </Form.Control>
diff --git a/front-end/src/components/VPLink/VPLinkModel.js b/front-end/src/components/VPLink/VPLinkModel.js
index a29e2bb..832c6fd 100644
--- a/front-end/src/components/VPLink/VPLinkModel.js
+++ b/front-end/src/components/VPLink/VPLinkModel.js
@@ -5,8 +5,8 @@ export default class VPLinkModel extends DefaultLinkModel {
     constructor() {
         super({
           type: 'default',
-          width: 5,
-          color: 'orange'
+          width: 2,
+          color: 'black'
         });
         this.registerListener({
             targetPortChanged: event => {
diff --git a/front-end/src/components/VPPort/VPPortModel.js b/front-end/src/components/VPPort/VPPortModel.js
index 4c0897a..c72778d 100644
--- a/front-end/src/components/VPPort/VPPortModel.js
+++ b/front-end/src/components/VPPort/VPPortModel.js
@@ -9,8 +9,16 @@ export default class VPPortModel extends DefaultPortModel {
       }
 
       canLinkToPort(port) {
-          // can't both be in or out ports
-          return port instanceof VPPortModel
-              && this.options.in !== port.options.in;
+          // if connecting to flow port, make sure this is a flow port
+          // and opposite of other's direction
+          if (port.options.name.includes("flow")) {
+              return this.options.name.includes("flow")
+                  && this.options.in !== port.options.in
+          // otherwise, make sure this is NOT a flow port, and ensure
+          // in/out compatibility
+          } else {
+              return !this.options.name.includes("flow")
+                  && this.options.in !== port.options.in
+          }
       }
 }
diff --git a/front-end/src/components/Workspace.js b/front-end/src/components/Workspace.js
index d12410b..1d06abb 100644
--- a/front-end/src/components/Workspace.js
+++ b/front-end/src/components/Workspace.js
@@ -53,7 +53,6 @@ class Workspace extends React.Component {
         API.getGlobalVars()
             .then(vars => {
                 this.setState({globals: vars});
-                this.model.globals = vars;
             })
             .catch(err => console.log(err));
     }
diff --git a/front-end/src/styles/CustomNode.css b/front-end/src/styles/CustomNode.css
index 0787cb9..2060c0b 100644
--- a/front-end/src/styles/CustomNode.css
+++ b/front-end/src/styles/CustomNode.css
@@ -14,6 +14,10 @@
     position: relative;
 }
 
+.custom-node-name {
+    margin-bottom: 3px;
+}
+
 .port-col {
     display: flex;
     flex-direction: column;
@@ -40,21 +44,41 @@
     border-left-color: mediumpurple;
 }
 
+.flow-port-div {
+    position: absolute;
+    top: -5px;
+}
+
+.flow-port-div-in {
+    left: -5px;
+}
+
+.flow-port-div-out {
+    left: 85%;
+}
+
+.flow-port {
+    width: 10px;
+    height: 10px;
+    border-radius: 5px;
+    background-color: purple;
+}
+
+.custom-node-icons {
+    width: 100%;
+    position: absolute;
+    display: flex;
+    justify-content: space-evenly;
+    align-items: center;
+}
+
 .custom-node-configure {
     font-size: 1.5rem;
     cursor: pointer;
-    position: absolute;
-    left: 25%;
-    top: 50%;
-    transform: translate(-50%, -50%);
 }
 
 .custom-node-tabular {
     cursor: pointer;
-    position: absolute;
-    right: 25%;
-    top: 25%;
-    transform: translate(50%, -25%);
 }
 
 .custom-node-description {