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The Trello integration turns your forms into an automated project management engine. Instead of manually copying data from emails, Flex Forms can instantly generate structured Trello Cards in specific columns (Lists) on specific Boards the moment a form is submitted.

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Enterprise Business Use Cases

Automated Support Queues

Route bug reports or feature requests directly into an “Inbox” List on your engineering team’s Trello Board, complete with the user’s uploaded screenshots.

Task Generation

When a new client completes an onboarding questionnaire, instantly generate a master Trello Card containing all their answers and place it in the “To Do” column for your project managers.

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Ultra-Detailed, Step-by-Step Setup Guide

Connecting Flex Forms to Trello requires generating both an API Key and an Authorization Token. Trello’s security model requires you to generate these separately. Follow these exact instructions.
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Step 1: Log into Trello

Open your web browser and navigate to Trello. Enter your credentials and ensure you are logged into the account that has edit access to the Board you want to use.
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Step 2: Access the Power-Ups Admin Portal

Open a new tab in your browser and navigate directly to this exact URL: https://trello.com/power-ups/admin. This is the developer portal where you generate API credentials.
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Step 3: Create a New Integration

On the Power-Ups Admin page, click the blue button labeled New.A form will appear. Fill it out with the following exact details:
  • Name: Flex Forms Website Integration
  • Workspace: Select your company’s Trello Workspace from the dropdown.
  • Email: Your administrator email address.
  • Support Contact: Your email address again.
  • Author: Your company name.
Click the Create button.
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Step 4: Copy the API Key

You will be redirected to the API Keys page for your new integration.At the top, you will see a long string of alphanumeric characters labeled API Key. Highlight it, right-click, and select Copy.
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Step 5: Inject the API Key into Flex Forms

Switch to your Flex Forms administrative dashboard in a new tab.
  1. Open Integrations (Flex Forms left rail) → Trello.
  2. Paste the string you copied in Step 4 into the API Key input field.
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Step 6: Generate the Authorization Token

Switch back to the Trello tab. Look immediately to the right of your API Key. You will see a small text link that says Token (usually written as “generate a Token”). Click exactly on this link.
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Step 7: Grant Access and Copy Token

A new window will open asking you to grant “Flex Forms Website Integration” access to your Trello account. Scroll to the bottom and click the green Allow button.Trello will now display a blank white page with a single, very long string of characters. This is your Authorization Token. Highlight the entire string and Copy it.
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Step 8: Inject Token and Save

Switch back to Flex Forms. Paste this long string into the API Token input field. Click the Save Settings button to finalize the secure connection.

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Masterclass: Routing Cards to Boards

Now that the connection is active, you must instruct Flex Forms exactly where to place the new Cards.
List ID Requirement: You must provide the specific List ID in the form’s integration settings. A “List” is the vertical column (e.g., “To Do”, “Doing”) on a Trello Board.How to find the List ID:
  1. Open your Trello Board in a browser.
  2. Add .json to the end of the URL (e.g., trello.com/b/xyz/my-board.json) and press Enter.
  3. Search the massive text wall (Ctrl+F) for the name of your List (e.g., “To Do”).
  4. Look for the "id": "xxxxxxxxxxxxx" string immediately preceding the name of the list. Copy that alphanumeric ID.

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Field Mapping Architecture

Trello is highly unstructured compared to a CRM. Every Card essentially has a Title and a Description. By default, Flex Forms intelligently compiles every single answer the user provided into a clean, markdown-formatted list and injects it into the Card Description.
You can map a specific form field to act as the primary Name (Title) of the Trello Card.The format is always: name=flex_forms_block_name
If you do not map the name field, Flex Forms will generate a generic title (e.g., “New Form Submission - [Date]”).

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Troubleshooting & Enterprise FAQs

The Problem: The server logs show a 401 invalid token error when attempting to create a Card.The Solution: The Token you pasted in Step 8 has expired or was revoked. Trello sometimes requires you to re-authorize apps. Go back to Step 6, generate a brand new Token, and update Flex Forms.
The Problem: The server logs show a 400 invalid idList error.The Solution: The List ID you pasted into the form settings is incorrect. Ensure you extracted the id of the actual List (column), NOT the id of the entire Board or the id of an individual Card.

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Configuration Reference

The following advanced settings are available in the Flex Forms UI for this integration. Use this reference to understand exactly how each field impacts the API payload.

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Global Settings

Located in Integrations in the Flex Forms left rail.
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password
required
Trello API Key From https://trello.com/power-ups/admin
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password
required
Trello Token

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Form-Level Settings

Located on the form hub Integrations tab for a specific form.
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remote_select
required
Destination list Board › list from boards you can access.
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select
Card title field Optional. Overrides the default title when the field has a value.
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text
Default card title Supports merge tags.
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textarea
Card description template Optional. Leave blank to send all fields as key: value lines. Supports .
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text
Label IDs Optional Trello label IDs for the new card.
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text
Member IDs Optional assignees.
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select
Due date field Optional. Value should parse as a date/time.
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select
default:"top"
Card positionOptions:
  • top: Top of list
  • bottom: Bottom of list
Last modified on September 7, 2026