Specifiction
For vendors
AdvertiseTop spots, featured rows, home sponsor Get listedAdd a product we don't cover yet Claim a listingFree: verify the domain, then correct your page Vendor dashboardNumbers, orders and placements
List your tool
Vendor dashboard
Tech riderRev. 20 Sept 2026

OpenAPI Server

Ch 216.5of 27 API Mocking Tools
  1. 1Runs onAPI, self-hosted
  2. 2CostsNot stated by the maker
  3. 3Dynamic responsesYes
  4. 4OpenAPI importYes
  5. 5Request matchingpath
  6. 6Local deploymentYes
  7. 7Supported protocolshttp, https
6 lines stated Written from the maker's own pages: github.com
Visit site Alternatives
The OpenAPI Server homepage

Overview

OpenAPI Server is ranked #21 of 27 in API mocking tools on Specifiction. It runs on API, Self-hosted.

Compared on API mocking tools

Dynamic responses
Yesgithub.com
OpenAPI import
Yesgithub.com
Request matching
pathgithub.com
Local deployment
Yesgithub.com
Supported protocols
http, httpsgithub.com

Facts

Purpose
OpenAPI Server is a local mock server for development that can proxy requests to a real backend.github.com · 4 Oct 2026
Intended use
The README describes using it to mock services while prototyping a single-page application without a working backend.github.com · 4 Oct 2026
End-to-end testing
Mocks can provide predictable API responses for end-to-end tests.github.com · 4 Oct 2026
OpenAPI support
It validates OpenAPI 3 and Swagger/OpenAPI 2 YAML specifications.github.com · 4 Oct 2026
Multiple specifications
It supports multiple specification files and directories and checks paths and methods for conflicts.github.com · 4 Oct 2026
Mock formats
Mocks can be JSON files, JavaScript modules, or Express middleware.github.com · 4 Oct 2026
Proxy and validation
It can proxy requests to another server and optionally validate responses.github.com · 4 Oct 2026
Other features
The README lists a static file server, HTTP and HTTPS support, watch mode, and configuration through environment variables, files, or CLI parameters.github.com · 4 Oct 2026
Integration
The project is an Express web server and can be used programmatically as an application or Express router, with custom Express middleware support.github.com · 4 Oct 2026
Install
The README instructs users to install it from its GitHub repository with npm.github.com · 4 Oct 2026
Default behavior
Mocks are enabled by default and take precedence over proxying when a matching mock exists.github.com · 4 Oct 2026
Notable limits
JavaScript mocks must run at runtime; the README says TypeScript mock files are not allowed because they cannot be transpiled at runtime.github.com · 4 Oct 2026
Publishing security
The README says npm releases use GitHub Actions OIDC trusted publishing with provenance.github.com · 4 Oct 2026
Maker location
The Intesys GitHub organization profile lists Italy as its location.github.com · 4 Oct 2026
Use case
The README describes using it to develop a single-page application before its backend is ready and to run end-to-end tests with predictable API responses.github.com · 5 Oct 2026
Mocking
Mocks can be JSON files, JavaScript modules, or Express middleware, and mocks are enabled by default.github.com · 5 Oct 2026
Proxy
When proxying is enabled, valid requests without a matching mock are forwarded to the configured backend.github.com · 5 Oct 2026
Response validation
The server can optionally validate responses.github.com · 5 Oct 2026
Additional features
It supports serving static files, HTTP and HTTPS, watch mode, and custom Express middleware.github.com · 5 Oct 2026
Configuration
Configuration is available through command-line options, environment variables, and environment files.github.com · 5 Oct 2026
Runtime requirement
The package declares Node.js version 18 or later as its engine requirement.github.com · 5 Oct 2026
License
The package declares the ISC license.github.com · 5 Oct 2026
Installation
The README gives a GitHub-based npm install command and a quick start that serves the API at localhost:3000/api.github.com · 5 Oct 2026

Best OpenAPI Server alternatives

See all 20
All accessCh 01 Microcks Free planAPIBrowser Free to start7.6 All accessCh 02 Mockzilla Free planAPILinux from $10/mo7.6 All accessCh 03 Parasoft SOAtest Free trialAndroidAPI 7.6 All accessCh 04 WireMock Free planFree trialAPI Free to start7.6 All accessCh 05 Mockttp Free planLinuxMac Free to start7.4 All accessCh 06 Mockoon Free trialAPILinux from €10/mo7.3

Where it ranks on Specifiction

Is OpenAPI Server yours?

Claim it for free: prove the domain, then correct facts, plans and screenshots. An editor reviews every change.

Claim it free Promote OpenAPI Server

Sources