Add an OpenAPI Documentation UI to Express

Unlike FastAPI or NestJS, Express doesn’t generate or serve anything OpenAPI-related on its own — whether your spec comes from hand-written YAML, swagger-jsdoc comments, or a schema library like zod-to-openapi, you’re always wiring up the JSON route and the viewer yourself. That’s actually the simple case for GetMan: there’s no bundled UI to disable first, just two routes to add.

Serve the spec

If you already have a static openapi.json file:

const openapiSpec = require('./openapi.json');

app.get('/openapi.json', (req, res) => res.json(openapiSpec));

If you’re generating it at runtime with swagger-jsdoc, call the generator once at startup and serve the result the same way:

const swaggerJsdoc = require('swagger-jsdoc');

const openapiSpec = swaggerJsdoc({
  definition: { openapi: '3.0.0', info: { title: 'My API', version: '1.0.0' } },
  apis: ['./routes/*.js'],
});

app.get('/openapi.json', (req, res) => res.json(openapiSpec));

Serve the docs UI

app.get('/docs', (req, res) => {
  res.send(`
    <div id="api-docs" style="height: 100vh"></div>
    <script src="https://cdn.getman.dev/latest/getman-ui.js"></script>
    <script>
      GetMan.launch(document.getElementById('api-docs'), { url: '/openapi.json' });
    </script>
  `);
});

That’s the whole integration — no swagger-ui-express middleware, no bundled assets to configure, and no build step. Visiting /docs fetches /openapi.json client-side and renders it the same way any of GetMan’s other embeds do.

Since Express has no bundled UI of its own to compare against, see the Swagger UI alternative comparison for feature-by-feature differences against the viewer most other frameworks default to.