Connect Instafill.ai to ChatGPT with MCP

Fill out PDF forms directly from ChatGPT. Connect once and ask ChatGPT to find, fill out, and download your forms using natural language.

Overview

MCP (Model Context Protocol) is an open standard that enables AI assistants to securely connect to external data sources and tools. The Instafill.ai form filler MCP server implements this protocol to give ChatGPT direct access to your Instafill.ai workspace - your forms, your profiles, and your fill history - without leaving the chat window.

Once connected, you can ask ChatGPT things like:

• "Show me all my forms"
• "Fill out the DS-11 form with my data"
• "Download the filled form from session abc-123"

ChatGPT handles the rest. It finds the right form, opens a secure widget for your data, tracks the fill job, and gives you a download link when it is done.

Before You Start

You need:

• A ChatGPT Plus, Team, or Enterprise account (not available on the free plan)
• An Instafill.ai account
• Developer mode enabled in ChatGPT

Setup: Connect Instafill.ai to ChatGPT

Step 1 - Enable Developer Mode in ChatGPT

Open ChatGPT and go to Settings > Apps > Advanced settings. Toggle Developer mode on.

Developer mode is what unlocks the ability to add custom MCP apps in ChatGPT. It is available on Plus, Team, and Enterprise - not on the free plan.

Step 2 - Create a New App

Inside the same Apps section, click "Create App".

Step 3 - Configure the App

Fill in the following:

Check the "I understand and want to continue" checkbox, then click "Create".

Step 4 - Authenticate with Instafill.ai

After creating the app, follow the OAuth flow:

• If you already have an Instafill.ai account - log in
• If you are new - sign up for free right in the flow
• Select the workspace you want ChatGPT to access
• Grant the AI assistant permission to access your forms

That is it. The connection is live.

How to Use It

Once connected, just type naturally in ChatGPT. Here are some things you can ask:

Browse your forms:

"List all my forms" "Find the W-4 form" "Show me all my filled forms"

Fill out a form:

"Fill out the I-9 form with my information"

ChatGPT will open a secure widget where you enter your data or select a saved profile. Your data goes directly to Instafill.ai and is not stored in your ChatGPT conversation.

Download a completed form:

"Download the form I just filled out" "Get the PDF for session abc-123"

ChatGPT returns a download link. Download links are valid for 10 minutes.

Manage profiles:

"Create a new profile" "Show me my saved profiles"

What ChatGPT Can Do with Your Instafill.ai Workspace

The integration gives ChatGPT access to 20 tools across your workspace:

The table above shows the most common actions. The full set of 20 tools also covers details like reading back the structured field data from a completed form, searching forms by name, setting which fields depend on others, and managing profile files and text.

New in the Latest Update

The MCP integration was rebuilt, and three new capabilities are worth calling out, because they let your assistant do things that previously required the Instafill.ai web app.

Inspect a form's fields (get_form_fields). Ask for the full field structure of any form - field names, descriptions, control types, and dependencies - right in the chat. Useful when you need to understand how a form is built, or want to use the field setup of one form to help fill another.

Edit a form's fields (update_form_fields). This is our Field editor, but in the chat. Field editor lets you correct how the AI reads a form - renaming a field, changing its type, adjusting its description, grouping it, or marking it to be skipped - so future fills come out right. Now you can request those same changes in plain language, and they are saved to the form and reflected in your workspace, exactly as if you had edited them in the web app.

Reuse the inputs from a past fill (get_fill_inputs). Retrieve the source data used on an earlier fill - files, text, and profiles - so you can re-run a fill or apply the same inputs to another form without re-entering anything.

How Form Filling Works in ChatGPT

ChatGPT uses a secure widget to collect your data. This is different from how it works in Claude Desktop or Claude.ai, where you provide data directly in the chat.

In ChatGPT, your form data is entered in a dedicated widget that sits outside the conversation. This means:

• Your data is not stored in chat history
• The widget transmits data directly to Instafill.ai servers
• The widget session expires after 10 minutes if not submitted

When you ask ChatGPT to fill out a form, it opens the widget automatically. You will see two options:

• Text Data - type or paste your information directly
• Profile - select a saved profile as the data source

After you submit the widget, ChatGPT tracks the fill job and returns your download link when it is ready.

Use Cases

Also Available in Claude, Claude Code, and Codex

If you use Claude Desktop, Claude.ai, Claude Code CLI, or Codex (CLI, IDE extension, or desktop app), you can connect the same Instafill.ai MCP server there too.

Go to Settings > Connectors > Add Custom Connector and enter:

https://api.instafill.ai/mcp

Claude and Codex users get the same 20 tools, with one difference: instead of the widget, they use the fill_form tool - you provide your data directly in chat, and the form fills without opening a separate widget. The server detects your client automatically and shows fill_form to Claude and Codex, and fill_form_widget to ChatGPT, so you only ever see the tool that works with your assistant.

Full setup instructions for Claude, Claude Code, and Codex are in Instafill.ai MCP Server Documentation.

Common Questions