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๐Ÿฆ‹ express-openapi-validator

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An OpenApi validator for ExpressJS that automatically validates API requests and responses using an OpenAPI 3 specification.

๐Ÿฆ‹express-openapi-validator is an unopinionated library that integrates with new and existing API applications. express-openapi-validator lets you write code the way you want; it does not impose any coding convention or project layout. Simply, install the validator onto your express app, point it to your OpenAPI 3 specification, then define and implement routes the way you prefer. See an example.


  • โœ”๏ธ request validation
  • โœ”๏ธ response validation (json only)
  • ๐Ÿ‘ฎ security validation / custom security functions
  • ๐Ÿ‘ฝ 3rd party / custom formats / custom data serialization-deserialization
  • ๐Ÿงต optionally auto-map OpenAPI endpoints to Express handler functions
  • โœ‚๏ธ $ref support; split specs over multiple files
  • ๐ŸŽˆ file upload


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npm install express-openapi-validator

## latest beta
npm install express-openapi-validator@4.14.0-beta.1


  1. Require/import the openapi validator
const OpenApiValidator = require('express-openapi-validator');


import * as OpenApiValidator from 'express-openapi-validator';
  1. Install the middleware

    apiSpec: './openapi.yaml',
    validateRequests: true, // (default)
    validateResponses: true, // false by default
  1. Register an error handler
app.use((err, req, res, next) => { // format error res.status(err.status || 500).json({ message: err.message, errors: err.errors, }); });

Important: Ensure express is configured with all relevant body parsers. Body parser middleware functions must be specified prior to any validated routes. See an example.


See the wiki for complete documenation



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