MCP & ChatGPT apps guide
How to add a ChatGPT app to your SaaS
Updated 2026-10-26
Short answer: A ChatGPT app is a remote MCP server plus, optionally, HTML components that ChatGPT renders inline. If you build a good MCP server first, the same server can power your Claude connector and your ChatGPT app.
What a ChatGPT app is made of
- A remote MCP server over HTTPS (Streamable HTTP).
- Tools with clear names, descriptions and input schemas.
- Optional UI: a tool can point to an HTML resource that ChatGPT shows as a card, table or map inside the chat.
- OAuth so each ChatGPT user signs into their own account in your product.
Steps
- Build and host the MCP server (see the MCP server guide).
- Add OAuth 2.1 with PKCE and protected resource metadata.
- Turn on developer mode in ChatGPT and add your server URL to test.
- Add UI components only where a table or chart beats text.
- Prepare listing material: description, privacy policy, test account, and screenshots, then submit for review in OpenAI's app directory process.
Claude and ChatGPT from one codebase
Claude supports remote MCP servers as custom connectors, so the same server works there. Keep ChatGPT-specific UI metadata optional so other clients ignore it cleanly.
Common mistakes
- Too many tools: the model picks the wrong one.
- Writes without a confirmation step.
- No test account for reviewers.
- Returning huge payloads that blow the context window.
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Besides running this directory, our team builds MCP servers and ChatGPT apps for small SaaS. Send your product URL and we'll record a short video of it working inside Claude, built only from your public API docs. Free, no call needed. Pilots start at $1,500. This service is separate from the agency rankings, which it never affects.
Prefer email? Write to us. Want an outside agency instead? See agencies that do MCP work.
Agencies in our index that mention MCP work
Listed in their normal directory order. Our own build service is not part of this list or the rankings.
- Teamvoy (Ukraine)
- AiAdvisors (Poland)
- Context Studios (Germany)
- AI Agency Manchester (United Kingdom)
- Focused (United States)
- Autor Technologies (Canada)
- Pentridge (United States)
- Hourglass AI (Australia)
- Enabled Minds (United States)
- AppStream Studio (United States)
Questions
Is a ChatGPT app different from a custom GPT?
Yes. A custom GPT is a configured assistant. An app connects ChatGPT to your product through MCP, usually with per-user sign-in.
Do I need UI components?
No. Many good apps are tools only. Add components when the answer is naturally a table, chart or list a user will click through.
Can the same server work in Claude?
Yes, if it follows the MCP spec. Claude can add it as a remote connector.
More MCP guides
- How to build an MCP server for your SaaS product
- MCP server development cost: what SaaS teams pay (estimates)
- MCP vs API: what SaaS teams actually need
- MCP server authentication: an OAuth 2.1 guide for SaaS teams
- MCP server for a REST API: generate from OpenAPI or hand-write?
- MCP server security and rate limiting checklist
- How to publish an MCP server: official registry, Smithery and awesome lists
- MCP server for CRM SaaS: tools, risks and scope
- MCP server for billing and subscription SaaS
- MCP server for scheduling and booking SaaS
- MCP server for healthcare SaaS: what is safe to build first
- MCP server for helpdesk and support SaaS
- Open-source example: Canny MCP server
Cost and effort figures on this page are rough estimates, not quotes.