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How to connect PDF Blocks MCP with ChatGPT

Connect ChatGPT to PDF Blocks MCP. Merge three pdfs and add watermark, split pdf into separate page files, and more using natural language, with authentication handled for you.

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PDF Blocks is a synchronous PDF processing API for merging, splitting, watermarking, securing, and reorganizing documents. Use it to automate PDF workflows with fast, programmatic operations.

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How to connect PDF Blocks MCP with ChatGPT

ChatGPT can take action across your apps and files, stay with a project for hours, and turn a goal into finished materials like sheets, slides, and docs, not just answers.

In this guide, I will explain the easiest and most secure way to connect your PDF Blocks account to ChatGPT via Composio Connect, so it can merge your PDFs, split documents, add watermarks, secure files, and reorder pages through natural language commands without ever putting your account credentials at risk.

Also integrate PDF Blocks with

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Why use Composio over default connectors?

  • Apps with read and write access. Default connectors mostly can read your data. Composio's PDF Blocks integration lets ChatGPT take actions like creating drafts, sending updates, labeling records, and more.
  • 1,500+ SaaS toolkits out of the box. Composio gives you instant access to a vast catalog of pre-built connectors, from Gmail and Slack to Notion, Linear, and Salesforce.
  • One MCP server for every app. Connect any of your applications on demand through a single endpoint, rather than juggling a separate server for each app.
  • Smart, context-aware tool loading. Unlike traditional MCP servers that dump every available tool into the LLM context window, Composio searches for and loads only the tools relevant to the task at hand.
  • Cross-app automation. Chain actions across multiple apps in a single run - fetch a thread, summarize it in Notion, and post highlights to Slack without leaving the conversation.

Prerequisites

Note: Composio connects through OAuth. You will be asked to sign in and approve specific permissions. Review the permission screen carefully if you are using a work account.

Step-by-step: Connect PDF Blocks to ChatGPT

1. Install the Composio plugin

Click the button. ChatGPT opens the Composio plugin page. Click Install plugin.

Install in ChatGPT

Composio plugin page in ChatGPT with the Install plugin button

You can also find it inside ChatGPT: go to Settings, open Plugins, search the marketplace for Composio, and click Install plugin.

2. Authenticate

After you install, ChatGPT asks you to authenticate with Composio. Log in and click Allow access to authorize ChatGPT to use your Composio account.

Composio login and Allow access screen for ChatGPT

3. Start using Composio

That is it. Composio tools are now available in ChatGPT. Type @Composio followed by your request, for example @Composio find unread PDF Blocks messages and summarize them, and it will run the actions you authorize. On first use it asks you to authorize PDF Blocks.

Option 2: Add Composio as an MCP server

If you cannot use the plugin marketplace, add Composio as a custom MCP server instead.

1. Open the MCP settings

In ChatGPT, go to Settings and open the Plugins section. Inside the Plugins page, click the MCP tab.

ChatGPT settings showing the Plugins page with the MCP tab selected

2. Add the server

Click Add server. In the Name field enter Composio, for Type select Streamable HTTP, and in the URL field paste the Composio MCP server URL:

bash
https://connect.composio.dev/mcp
ChatGPT Add server dialog with the name Composio, type Streamable HTTP, and the Composio MCP URL

Then click Save. The Composio server now appears in your MCP plugins list.

ChatGPT Plugins page showing the Composio MCP server added to the list

3. Authenticate

Click Authenticate on the Composio entry, log in via Composio, and click Allow access. Composio tools are then available in ChatGPT the same way as with the plugin.

What you can do after connecting PDF Blocks

  • Merge three PDFs and add watermark
  • Split PDF into separate page files
  • Protect PDF with password and permissions

Security + privacy notes (important)

  • Use least-privilege access: Only grant permissions you actually need.
  • Review OAuth permissions before approving: Make sure requested scopes match what you expect Composio and ChatGPT to do.
  • Keep write actions human-reviewed: For actions like sending messages, creating labels, or editing drafts, keep manual confirmation enabled.
  • Be careful with sensitive data: Avoid using this setup with highly sensitive information unless allowed by your personal, company, or client policies.
TOOLS

Supported Tools

Every PDF Blocks action and event your agent gets out of the box.

Add Image Watermark

Add a PNG or JPEG image as a watermark on all or selected PDF pages.

Add PDF Password

Create an encrypted copy of a PDF that requires a password to open.

Add PDF Restrictions

Create an encrypted PDF copy with explicit permissions for copying, editing, printing, forms, assembly, and accessibility.

Add Text Watermark

Add up to three styled text lines as a watermark on all or selected PDF pages.

Extract PDF Pages

Create a PDF containing selected source pages in their original order.

Merge PDFs

Merge PDF files into one PDF in the exact order provided.

Remove PDF Pages

Create a PDF with selected pages removed while preserving the remaining page order.

Remove PDF Password

Create an unencrypted copy of a password-protected PDF using its current password.

Remove PDF Restrictions

Create a PDF copy with permission restrictions cleared.

Remove PDF Signatures

Create a PDF copy with all digital signatures and timestamps removed.

Reorder PDF Pages

Create a PDF in an exact page order, optionally dropping or repeating source pages.

Reverse PDF Pages

Create a PDF with the complete page order reversed.

Rotate PDF Pages

Rotate all or selected PDF pages by a supported multiple of 90 degrees.

Split PDF at Page

Split a PDF into exactly two downloadable PDFs at a page boundary; the selected page starts the second PDF.

Split PDF by Page Count

Split a PDF into consecutive downloadable PDFs containing up to a fixed number of pages each.

Split PDF by Page Groups

Create one downloadable PDF for each caller-defined ordered group of source pages.

Split PDF by Size

Split a PDF into downloadable PDFs no larger than a requested byte limit.

FRAMEWORKS

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FAQ

Frequently asked questions

With a standalone PDF Blocks MCP server, the agents and LLMs can only access a fixed set of PDF Blocks tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from PDF Blocks and many other apps based on the task at hand, all through a single MCP endpoint.

Yes, you can. ChatGPT fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right PDF Blocks tools.

Yes, absolutely. You can configure which PDF Blocks scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your PDF Blocks data and credentials are handled as safely as possible.

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