Getting started

You write a contract in YAML. seampact generates the types, the validators, the server routes and the clients. You write the handlers. This guide builds a notes API on the server of your choice and calls it from React.

You need Node.js 24 or later and npm to run the seampact command on Node. Spring Boot, Laravel, Symfony and Python install through their own tools: install in other ecosystems.

1. Install seampact with npm and start a project.
2. Your first API: write the contract, generate, write the handlers for your server and run the app.
3. Call it from React: generate a typed client and hooks.
4. Check it in CI: fail the build when the generated files drift. Diff a change shows what an edit breaks for clients.

Also:

• Install in other ecosystems: Maven Central, Packagist, PyPI, the compiler binary and a checkout.
• Add seampact to an existing app: move routes one at a time.
• Project layout: what each file is.
• Work with an AI agent: guard rails for an agent.
• Commands per stack: how to type generate, check and the others on Gradle, Maven, PHP and Python.
• What is seampact and the glossary.
• Every key of seampact.config.yaml: the config reference.
• Something fails: troubleshooting.

Next: Install