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A REST API simplifies interaction with your form data, allowing for automation and integration. Following RESTful principles, it seamlessly connects to retrieve, create, and modify form data.

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Introduction

The Fillout API lets you access information about your Fillout account programmatically, without using the Fillout site. It is primarily for Fillout users and for 3rd party developers that want to build services on top of Fillout or access their submission data. You can access a list of all your forms and the submissions for each form via the API.

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Authentication

Generate and view your API key in the Developer settings tab of your account. You can revoke or Regenerate your API key at any time via the dashboard. Screenshot 2025-11-06 at 4.07.30 PM.png To authenticate your requests, you need to provide your API key in the Authorization header in the following format:
Replace <your-api-key> with the API key obtained from your Fillout account.
If you’re self-hosting Fillout or using the EU agent, a different URL will appear in the dashboard.
You can obtain your API base URL in the API dashboard. Typically, it will be https://api.fillout.com.
You can also use access tokens granted via a Fillout 3rd party integration. If you’re looking to build an integration, see this article.

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Find a question’s ID

Responses from the API identify each question by its ID, like "id": "abcdef". To find a question’s ID, open your form in the editor, click the three dots on the question, and hover over Info. Field menu with Info showing the field’s unique identifier Question IDs are created automatically and can’t be changed.

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Rate limits

All endpoints above are limited to being called no more than 5 times per second, per Account/API key.

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Related article

Create Fillout Apps

Build integrations that link Fillout with 3rd party apps.