Grandmaster Flash

Connection guide

Connect Claude or ChatGPT
to Grandmaster Flash.

The connector lets your assistant create and update decks in your Grandmaster Flash library. You add it once, then ask for decks in any chat.

Sign in with the same email address as the mobile app. You’ll receive a one-time code and approve access to your private account.

The server address

Use this address for either assistant:

https://api.grandmasterflash.app/mcp

01 · Claude

Add a custom connector.

Works on every Claude plan; the Free plan allows one custom connector. Set it up in Claude on the web.

claude.ai Connectors Customize → Connectors + Add Browse connectors Add custom connector Add custom connector Name Grandmaster Flash Remote MCP server URL https://api.grandmasterflash.app/mcp Continue Authentication Sign in now OAuth client Use Claude’s published identity Register automatically Use your own OAuth client Add Connect Claude Email [email protected] Send code Check your email Code • • • • • • Continue Allow Claude? Claude will be able to read and change your Grandmaster Flash decks. Cancel Allow Reply to Claude… + Connectors Web search Grandmaster Flash

1 of 5 · Open Customize → Connectors

  1. On claude.ai, open Customize → Connectors (Settings → Connectors in some versions). Choose + Add, then Add custom connector.
  2. Name it Grandmaster Flash, paste the server address, and choose Continue.
  3. Keep OAuth sign-in. Under OAuth client, choose Register automatically. Leave request headers empty, then choose Add.
  4. Choose Connect. Enter the email you use in Grandmaster Flash and choose Send code. Type the code from your inbox, then choose Allow.
  5. In a chat, open the + menu, choose Connectors, and switch on Grandmaster Flash.

If Claude asks about request headers or your own OAuth client, leave them empty: this server registers the connection for you. On Team or Enterprise, an owner may need to add the connector under Organization settings first. Claude’s current connection guide.

02 · ChatGPT

Create a custom MCP app.

Check your workspace first. Creating and editing decks needs MCP write actions. OpenAI currently documents full custom MCP support for eligible Business, Enterprise, and Edu workspaces on ChatGPT web. Pro’s read/fetch access alone cannot create decks. If your workspace doesn’t have this access, use Claude.

chatgpt.com Settings → Apps Enabled apps Advanced settings Developer mode Create app Name Grandmaster Flash MCP server URL https://api.grandmasterflash.app/mcp Authentication Choose… OAuth Create app Grandmaster Flash · OAuth Scan Tools Connect ChatGPT Email [email protected] Send code Check your email Code • • • • • • Continue Allow ChatGPT? ChatGPT will be able to read and change your Grandmaster Flash decks. Cancel Allow Create app Tools found Create Grandmaster Flash Dev Ask anything @Grandmaster Flash + Add photos & files Grandmaster Flash

1 of 5 · Turn on Developer mode

  1. On chatgpt.com, open Settings → Apps → Advanced settings and turn on Developer mode. An admin may need to allow it first.
  2. Choose Apps → Create. Name it Grandmaster Flash, paste the server address, and choose OAuth authentication.
  3. Choose Scan Tools. Enter the email you use in Grandmaster Flash and choose Send code. Type the code from your inbox, then choose Allow.
  4. After the scan finishes, choose Create. The app appears in your apps with a Dev label.
  5. In a new chat, select Grandmaster Flash from the tools menu or @mention it. Approve its actions when asked.

Business admins can also turn on developer mode while creating an app in Workspace settings → Apps → Create, and can publish the draft to other workspace members. Leave optional custom client credentials blank. Setup labels and availability can change; check OpenAI’s current MCP guide if you don’t see these options.

03 · Your first deck

Ask for something you’ll use.

Once connected, try this:

Using Grandmaster Flash, make a French deck for ordering at a café in Paris: greetings, drinks and pastries, asking for the bill, and small talk with the waiter. Include English translations and an example sentence for each card. Use a male Parisian voice for the audio.

Your assistant shows what it made; ask it to change anything. Then open the app and sync your library. Let the deck and audio finish downloading before going offline. More example prompts.

Later, ask your assistant to correct a translation, add examples, or work through flagged cards. You can revoke the connection in the app under Settings → Assistants.

If you get stuck

My deck isn’t in the app.

Check that the assistant and app use the same email. Ask the assistant to list your decks to confirm it saved the content, then sync the app while online.

I can’t see the connector or its tools.

Check your plan and workspace permissions. Enable the connector for your message or conversation. If tools are stale, reconnect in Claude or ask your ChatGPT workspace admin to refresh the app’s tools.

My sign-in code hasn’t arrived.

Check spam and that the email address is correct. Request a new code if the old one expired. Never send us the code.

Audio doesn’t play offline.

Audio needs to finish downloading while you’re online. Use Settings → Downloads → Retry downloads if a download failed.

Still stuck? Send us a support message.