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CAI.com — a custodial @cai.com email, multi-chain stablecoin wallet, and MCP-installable agent API

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CAI.com — a custodial @cai.com email, multi-chain stablecoin wallet, and MCP-installable agent API

A custodial email, a stablecoin wallet, a credential vault, and an agent-ready API — all at one @cai.com address.

This post walks through what CAI is, what you get when you sign up, and how to wire the agent side into any MCP-compatible host.

What you get at cai.com/app

A free @cai.com email comes with four product surfaces, all under one account:

  • A real inbox at @cai.com. Send and receive mail like any other address. The signup gives you the address; the dashboard gives you the SMTP/IMAP credentials if you want to use a desktop client.
  • A custodial multi-chain stablecoin wallet. Built in. Six chains. External wallets supported. MoonPay for fiat on-ramp (partial-live, third-party KYC and region limits apply — see cai.com/capabilities.html).
  • A user vault for site credentials. Store website logins and passwords. The agent you build retrieves them when needed, with your explicit confirmation. The vault is for your site credentials, not the agent's API key.
  • An API key for the agent you build or use. Free tier covers read scopes; pay and full scopes may require verification. The key is in the account dashboard.

How the signup works

The signup at cai.com/app is four steps. About 2 minutes.

  1. Go to cai.com/app. Pick "Apply for @cai.com email."
  2. Enter your name. That's the only field on the first screen.
  3. CAI emails a 6-digit verification code to the address you provide. The code expires in 15 minutes. The email has a one-time link, not the code — copy the code from the email and paste it into the form.
  4. Enter the code, create a password, and you're done.

At the end you have:

  • A @cai.com email address.
  • A custodial multi-chain stablecoin wallet.
  • A user vault for site credentials.
  • An API key for the agent you build or use.

No card. The email is free.

The agent side (for the technical reader)

For the technical reader, the agent side is the reason to look at CAI. The install is one command:

npm i -g @cailab/mcp
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The package is the MCP server — a thin wrapper around the CAI HTTPS Edge API at https://api.cai.com/functions/v1. It drops into MCP-compatible hosts including OpenClaw, Hermes, Codex, and Cursor (see cai.com/developers.html for the current host list). Once installed, the agent can call GET /get-identity, POST /get-wallet-balances, POST /wallet-custodial-transfer, and the rest of the CAI surface — without the user pasting a private key in chat.

The contract an agent reads first is cai.com/skill.md. It's the canonical source-of-truth for what CAI can do, written in a format agents parse. The companion artifact is the A2A Agent Card at cai.com/.well-known/agent.json — that's how agents discover CAI in agent-to-agent registries.

If you tried this and hit a bug

Comment below with:

  1. What you ran — the install command, the request, the MCP host config. Copy the actual command or request.
  2. What you expected — one sentence.
  3. What you got — the error message, the empty response, the unexpected behavior. Paste it verbatim.
  4. Your environment — OS, Node version, the MCP host (OpenClaw / Hermes / Codex / Cursor / other), the CAI account tier if relevant.

Every comment on this article gets read. Bug reports will be replied to within 24 hours. Friction points shape what we document next.

Documentation: cai.com/skill.md · cai.com/developers.html · cai.com/app to sign up.

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