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Flow Builder is a visual, drag-and-drop conversation editor that lets you design AI assistant scripts without writing code. You build multi-step conversation flows by connecting nodes that represent different actions and decision points.

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When to use Flow Builder

Use Flow Builder for

  • Structured conversation scripts
  • Multi-path decision trees
  • Complex call flows with branching logic
  • Visual thinkers who prefer diagrams over text

Use the classic editor for

  • Simple, linear conversations
  • Highly dynamic AI responses
  • Quick prompt iterations
  • Text-focused editing

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Getting started

1

Open your assistant

Navigate to Assistants and click on the assistant you want to edit.
2

Find Flow Builder

Scroll to the System Prompt section and click the Flow Builder tab.
3

Launch the editor

Click Launch Flow Builder. A full-screen editor opens.
4

Choose how to start

  • Continue with existing — edit your current flow.
  • Start from scratch — begin with just a Start node.
  • Start with template — load a pre-built conversation template.

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Interface overview

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Canvas (centre)

The main workspace where you build your flow:
  • Nodes — drag to reposition anywhere on the canvas.
  • Connections — lines showing the flow between nodes.
  • Zoom controls — zoom in/out and fit to view.
  • Pan — click and drag on empty space to move around.

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Bottom toolbar

ButtonAction
Auto LayoutAutomatically arranges nodes neatly
DuplicateCopies the selected node
DeleteRemoves the selected node or connection
+ Add NodeAdds a new node to the canvas

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Settings panel (right side)

Configure your assistant’s personality and conversation behaviour:
  • Agent name — the name your AI uses to introduce itself.
  • Agent type — Sales, Support, Survey, etc.
  • Language — spoken language for calls.
  • Assertiveness — how persistent the AI should be (Low / Medium / High).
  • Humor — level of humour in responses (Off / Low / Medium / High).
  • Variables — pre-call data fields available in messages.
  • Post-call fields — data to extract from the conversation after the call ends.

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Node types

Flow Builder has five node types, each with a specific purpose.

Start node (green)

The entry point of every conversation. Every flow must have exactly one Start node.Properties:
  • Greeting — the initial message when the call begins.
Example: "Hi, this is Sarah from Acme Insurance. How are you today?"

Speak node (blue)

Delivers a pre-written message exactly as specified. Use this when you need precise wording.Properties:
  • Text — the exact message to speak.
  • Outcomes — different paths based on the customer’s response.
Example: "We're offering a limited-time 20% discount on all plans. Would you like to hear more?"

Prompt node (purple)

Gives the AI instructions on how to respond. More flexible than Speak nodes — the AI generates contextual responses.Properties:
  • Prompt — instructions for the AI.
  • Outcomes — different paths based on response categories.
Example prompt: "Ask the customer about their current insurance coverage. Be conversational and empathetic."

Action node (orange)

Executes special actions during the call.Action types:
  • Call forward — transfer to another number.
  • Book appointment — schedule using a connected calendar.
  • Custom action — trigger a custom mid-call tool.

End node (red)

Terminates the call or transfers to another destination.End types:
  • End call — hang up with a closing message.
  • Forward call — transfer to a phone number.
  • Transfer agent — hand off to another assistant.

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Working with nodes

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Adding nodes

  1. Click + Add Node in the bottom toolbar.
  2. Select the node type from the dropdown.
  3. Drag the new node to your desired position.

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Connecting nodes

  1. Hover over a node’s bottom edge to reveal the output handle (small circle).
  2. Click and drag from the output handle to another node’s input handle (top edge).
  3. Release to create the connection.

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Editing nodes

  1. Click on any node to select it.
  2. The node’s properties appear in a side panel.
  3. Edit the text, prompt, or settings.

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Deleting nodes

Select a node and press the Delete key, or click the delete button in the bottom toolbar.
The Start node cannot be deleted. Every flow must have exactly one Start node.

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Branching with outcomes

Speak and Prompt nodes can have multiple outcomes — different paths based on how the customer responds. Adding outcomes:
  1. Select a Speak or Prompt node.
  2. In the properties panel, find Outcomes and click Add Outcome.
  3. Name the outcome (e.g., “Interested”, “Not interested”, “Wants callback”).
Connecting outcomes: Each outcome appears as a coloured dot at the bottom of the node. Connect each outcome to a different destination node to create branching logic. 
[Start] → [Prompt: "Ask if interested"]
                  ↓
      ┌───────────┼───────────┐
      ↓           ↓           ↓
 [Interested]  [Maybe]  [Not interested]
      ↓           ↓           ↓
 [Book demo]  [Send info]  [Thank & end]

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Variables

Add pre-call data that can be referenced in your messages:
  1. Click Add Variable in the Settings panel.
  2. Enter a Name (e.g., customer_name).
  3. Set a Default Value.
Reference variables in messages with curly braces: {variable_name} Example: "Hi {customer_name}, I see you were interested in our {product_interest}."

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Post-call fields

Define data to extract from the conversation:
  1. Click Add Field in the Settings panel.
  2. Enter a Name, Type, and Description.
  3. The AI will attempt to fill these fields based on what was discussed.
Supported types: string, number, boolean

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Import and export

  1. Open the Settings panel.
  2. Scroll to the bottom.
  3. Click Export JSON and save the file.
Export your flows regularly as backups. You can also share flows with team members by sending the JSON file.

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Voicemail settings

Configure what happens when voicemail is detected during outbound calls:
  • Voicemail message — the message to leave if voicemail answers.
  • End call on voicemail — toggle to automatically hang up instead of leaving a message.

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Saving your flow

Click Save in the top-right corner to save your flow to the assistant.
The flow is stored as JSON in your assistant’s system prompt field. If you switch to the classic editor, you’ll see the raw JSON data.

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Best practices

Start simple

Begin with a basic flow and add complexity gradually. Test at each stage before adding more branches.

Use Prompt nodes for flexibility

Prompt nodes give the AI room to respond naturally. Reserve Speak nodes for moments that require exact wording.

Plan your outcomes first

Sketch the main paths — positive, negative, and neutral responses — before building the flow.

Test every path

Make test calls covering all outcomes. Verify each path leads to the right destination node.

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Troubleshooting

  • Ensure you’re dragging from an output handle (bottom) to an input handle (top).
  • Check that you’re not creating a circular connection.
  • The Start node only has an output; End nodes only have an input.
  • Check your internet connection.
  • Ensure you have at least one node besides the Start node.
  • Look for validation errors in the Settings panel.
  • Use Speak nodes when exact wording is required.
  • Make Prompt node instructions more specific.
  • Check that outcomes are clearly defined and connected.