OpenAPI Server

Self-hosted · API

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Freedom report

One barScore 5.3

Free tierNo free tier on record
Open codeNo open-source code on record
Runs widely0 of 6 device platforms
DocumentedPlans, terms and facts published

OpenAPI Server is ranked #17 of 27 in API mocking tools on Freedom251. It runs on API, Self-hosted.

Compared on API mocking tools

Dynamic responses: Yes
OpenAPI import: Yes
Request matching: path
Local deployment: Yes
Supported protocols: http, https

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The record

Purpose: OpenAPI Server is a local mock server for development that can proxy requests to a real backend.
Intended use: The README describes using it to mock services while prototyping a single-page application without a working backend.
End-to-end testing: Mocks can provide predictable API responses for end-to-end tests.
OpenAPI support: It validates OpenAPI 3 and Swagger/OpenAPI 2 YAML specifications.
Multiple specifications: It supports multiple specification files and directories and checks paths and methods for conflicts.
Mock formats: Mocks can be JSON files, JavaScript modules, or Express middleware.
Proxy and validation: It can proxy requests to another server and optionally validate responses.
Other features: The README lists a static file server, HTTP and HTTPS support, watch mode, and configuration through environment variables, files, or CLI parameters.
Integration: The project is an Express web server and can be used programmatically as an application or Express router, with custom Express middleware support.
Install: The README instructs users to install it from its GitHub repository with npm.
Default behavior: Mocks are enabled by default and take precedence over proxying when a matching mock exists.
Notable limits: JavaScript mocks must run at runtime; the README says TypeScript mock files are not allowed because they cannot be transpiled at runtime.
Publishing security: The README says npm releases use GitHub Actions OIDC trusted publishing with provenance.
Maker location: The Intesys GitHub organization profile lists Italy as its location.

Where it ranks on Freedom251

Best API Mocking Tools in 2026#17 of 27

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Sources

github.com/intesys/openapi-server· checked 4 Oct 2026
github.com/intesys· checked 4 Oct 2026
github.com/intesys/openapi-server/blob/master/pack· checked 5 Oct 2026