← callback.cards

Connect Callback in Claude

Add the connector on the web, then review on your phone.

Callback plugs into claude.ai as a custom MCP connector. Add it once and Claude can save what you learn straight to your account — no install needed to get started.

invite-only beta  ·  hello@callback.cards
Connector URL — you'll paste this into Claude:
https://api.callback.cards/mcp

Connect in four steps

1

Add the custom connector

In claude.ai, go to Settings → Connectors → Add custom connector and paste the URL:

https://api.callback.cards/mcp

2

Sign in or create your account

When Claude prompts you to authorize the connector, sign in to your Callback account — or create one if this is your first time.

Callback is invite-only right now. If you're not on the allowlist yet, email hello@callback.cards and we'll get you in.

3

Chat with Claude

Learn the way you already do — any topic, any depth. At the end of a learning conversation, ask Claude to save it (try quiz me on this). Claude distills what you worked through into a handful of well-formed cards and saves them to your account.

4

Install the app and review

Get the Android app and sign in with the same account. It pings you when cards come due and quizzes you on a spaced-repetition schedule — each review timed to land just before the memory fades.

Get the Android app →

Prefer the command line?

Using Claude Code? There's a skill that does the same thing from the CLI. Install it with curl -fsSL https://callback.cards/install.sh | bash — then say "quiz me on this" at the end of a session. The connector above is the easiest way in for most people.