ChatGPT, Gemini and other apps
The X3 MCP server (https://api.x3growth.io/mcp, Streamable HTTP) signs in with OAuth 2.1 (PKCE,
client ID metadata documents or dynamic registration). Each person connects with their own X3 login –
no key. /mcp answers every request without a token – initialize included – with a 401 OAuth challenge,
so every app detects the sign-in when you add it. The dashboard card Zu Claude hinzufügen
(Team › KI-Apps) has a button per app.
No account yet? The public docs endpoint https://api.x3growth.io/mcp/public (server x3-docs) serves
docs, setup recipes and event validation without sign-in and without data
(Public docs endpoint).
| App | How | Status |
|---|---|---|
| Claude (web, desktop, mobile) | pre-filled install link – Claude | ready |
| Claude Code | claude mcp add --scope user --transport http x3 https://api.x3growth.io/mcp – Claude Code | ready |
| ChatGPT | chatgpt.com/plugins → + → Add custom MCP server → name X3, the URL, authentication OAuth → sign in to X3. Plus/Pro: developer mode, read-only; Business/Enterprise: an admin enables custom MCP apps | ready |
| Gemini CLI | gemini mcp add --scope user --transport http x3 https://api.x3growth.io/mcp, then start gemini – the browser opens for the sign-in | ready |
| Cursor, VS Code | install deep links on the dashboard card | ready |
| Grok | xAI does not document the sign-in callback of custom connectors yet, so X3 cannot allow it safely | not yet |
| Gemini app | custom apps are limited to the US and English so far and sign in through a patterned relay URL | not yet |
Allowed sign-in callbacks
X3 only accepts exact callback URLs (no wildcards): Claude's hosted callbacks, ChatGPT's stable
callback https://chatgpt.com/connector_platform_oauth_redirect, Cursor's and VS Code's web callbacks,
and loopback addresses (http://localhost:<port>/…, http://127.0.0.1:<port>/…) for desktop and
command-line clients such as Claude Code, Cursor, VS Code and Gemini CLI. Self-hosted deployments can
add exact URLs with X3_OAUTH_EXTRA_REDIRECTS (environment).
Website setup in every app
The prompt connect_website walks any MCP client through connecting a website end to end; in Gemini CLI
it is the slash command /connect_website. Claude users can install the same workflow as a skill:
Claude skill and plugin.