v1.12 — spec-driven mock server

One Zod schema per route.
Docs, tests, and runtime validation.

DocTreen is a code-first API documentation library for Node.js. Define your route shape once and get an interactive docs UI, OpenAPI 3.1 export, runnable integration flows, and 422-on-invalid-request validation — for Express, Fastify, Hono, Koa, and NestJS.

Read the docsLive demo
npm install doctreen
import express from 'express';
import { z } from 'zod';
import { expressAdapter, defineRoute } from 'doctreen/express';

const app = express();
app.use(express.json());

app.post('/users', defineRoute(
  (req, res) => res.status(201).json({ id: 1, ...req.body }),
  {
    description: 'Create a user',
    request:  { body: z.object({ name: z.string(), email: z.string().email() }) },
    response: z.object({ id: z.number(), name: z.string(), email: z.string() }),
    errors:   { 409: 'Email already in use' },
  }
));

// Mount docs UI + OpenAPI 3.1 + runtime validation in one place.
app.use(expressAdapter(app, {
  meta:     { title: 'My API', version: '1.0.0' },
  validate: true,
}));
  • Interactive docs UI at /docs — zero-dependency HTML
  • OpenAPI 3.1 export with $ref dedup, tags, callbacks, webhooks
  • Runtime validation: same Zod schema returns a structured 422
  • Schema drift detection against live traffic, CI-ready
  • Spec-driven mock server: npx doctreen mock --from <url|file>
  • Postman Collection v2.1 export + runnable integration flows

Works with your stack

  • Express
  • Fastify
  • Hono
  • Koa
  • NestJS

Drop it next to your existing router.

No router rewrite, no separate spec file, no decorator boilerplate.

Quick start