Gemmein documentation
Give the app you are building with AI sign-in, saved data, payments, credits, AI tools, email, and hosting for its pages. Your users and their data live in Gemmein — so the rules hold whatever the code does.
Whether you are starting from an idea with nothing built yet or already have an app, begin with the Quickstart. Every feature is documented here.
For your AI tool: Gemmein hosts the app and is its backend. One SDK,
@gemmein/sdk, covers sign-in, data with one safety rule per collection, Stripe
payments, credits, AI tools, relays and email. Every call goes through the SDK's methods, and security is
configured on Gemmein's servers, never from the client. A machine-readable copy of these docs is included in the package,
so your AI tool can read it.
Get started
Quickstart
Install the SDK and build a signed-in app that stores data, in about an hour.
pick your AIConnect your AI
ChatGPT or Claude in a chat, a coding tool such as Claude Code, Cursor or Codex on your computer, or the guide on its own. What each can do, and what needs your approval.
for your agentMCP server
Docs, explainers and a live check of your safety rules, as tools for your AI coding agent. Run it with npx -y @gemmein/mcp.
Build
Sign-in & sessions
Add sign-in with a code sent by email, no passwords. Sessions, sign-out and account deletion.
Data & safety rules
Save your app’s data in collections with one safety rule each. The server enforces who reads and writes.
Payments
Take payments for subscriptions and one-off sales through Stripe, with no webhook to build. Any provider that signs its webhooks can grant access the same way, through a relay.
Credits
A balance each person holds and your app spends. It fills from a pack they buy or a grant you give, and a call can cost credits. A spend never takes it below zero, and a pack never expires.
AI tools
Call OpenAI, Anthropic, Google or any OpenAI-compatible provider through Gemmein with your own provider key, which never reaches the browser. Each call spends the credits you set on the tool it names, or one credit for an unnamed call.
Send sign-in codes, notifications and your answers from the Inbox from your own domain. Replies land in the Inbox.
Relays
Run built-in actions when a provider sends a webhook, on a schedule, or when a record changes. One JSON file, no code.
Mobile
The same API from an Expo or Swift app: sign-in codes, private records, sealed files, credits, AI tools, and the store account token a RevenueCat purchase is recorded against.
Conflicts
Unique usernames, limited stock and simultaneous edits. A conflict returns 409 for your code to handle.
Run your app
Your site
Gemmein hosts your app’s pages: a private preview the moment your AI publishes, a live site when you approve a version, versions to go back to, and offline when you ask.
Your own domain
Show your live site at www.yourapp.com: two DNS records, and Gemmein checks them and sets up https.
Go live
What is left to do before your app goes live, and what goes live with it.
Dashboard guides
One guide per dashboard page, step by step, with screenshots.
Reference
SDK reference
Every method, signature, and return shape of @gemmein/sdk.
Errors
Every failure returns a typed code and a message you can show. Branch on the code.
Testing in CI
Test your safety rules in CI with live calls against the server that enforces them.
Changelog
What changed in each Gemmein release, newest first.
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