I’m also singing ts-rest.com’s praise these days. Admittedly a small project with <25 endpoints atm, but holy crap, I am saving SO MUCH TIME on implementations, documentation, and bug hunting.

I have separate packages (in a monorepo) for the “contract definition” and the “API implementation” (which is currently NextJS, but likely Express in the future — and the migration path looks like very smooth sailing)

Request/response validation, OpenAPI spec, fetch & react-query clients without any additional effort. Mocks for tests auto-generate based on contract definition as MSW. It almost feels too good to be true.