Dev tools · alternatives · 2026

24 alternatives to DoppelAPI

The digital twin of your be instant mock server from API

Below are 24 products that do a similar job, ranked by how close each is in meaning and then by launch-day votes.

1. 1
   Mock API Generator▲555

   Generate custom data & API to build apps in less than 30s

   2021 · retool.com · its alternatives →

2. 2
   Mitmproxy2swagger – Automagically reverse-engineer REST APIs▲691

   Automagically reverse-engineer REST APIs via capturing traffic - alufers/mitmproxy2swagger

   2022 · github.com · its alternatives →

3. 3
   Apidog▲570

   Development teams often struggle with using multiple tools like Postman and Swagger for API design, development, and testing. This fragmented approach leads to outdated API specs and chaotic collaboration. So we built Apidog: a single, unified API platform for team collaboration. It has a beautiful interface that makes it easy to create API spec, generate request data from API spec, validate responses, create mock data, orchestrate test scenarios, and publish API documentation. Apidog = Postman + Swagger + Mock + JMeter.

   2024 · apidog.com · its alternatives →

4. 4
   A faster way to prototype your APIs using OpenAPI 3 and Swagger UI▲77

   A generator for OpenAPI 3. Contribute to egorsmkv/openapi3-generator development by creating an account on GitHub.

   2020 · github.com · its alternatives →

5. 5
   Mockaroo▲354

   A realistic data generator to test your app

   2015 · mockaroo.com · its alternatives →

6. 6
   InterimAPI▲68

   Custom API endpoints with realistic fake data in seconds

   2022 · interimapi.com · its alternatives →

7. 7
   Swagger Inspector▲141

   Free online tool to test APIs and autogenerate documentation

   2018 · swagger.io · its alternatives →

8. 8
   Prism▲79

   Accelerate API development with realistic mock servers

   2023 · stoplight.io · its alternatives →

9. 9
   OpenAPI mocks that don't suck – realistic test data, quick setup▲13

   Hi HN! I'm Ankit, the founder of Beeceptor, a request mocking and intercepting tool. This time, I built something new to address a pain I’ve personally felt (and heard from dozens of QA, frontend, and platform teams): making OpenAPI specs actually useful during development. API contracts just sit around as docs often. What if you could 'activate' them, instantly have a realistic, hosted mock server-with contract validation, smart test data, and early usage? So I made _Mockaroo for OpenAPI_, but with brains. It spins up a hosted mock server from your spec in one click. It: - Generates…

   2025 · beeceptor.com · its alternatives →

10. 10
    Mockoon – mock REST APIs in seconds▲68

    Mockoon is the easiest and quickest way to run mock REST API servers. No remote deployment, no account required, free, open source and cross-platform.

    2017 · mockoon.com · its alternatives →

11. 11
    API 200▲14

    I frequently face numerous challenges when working with third-party APIs - error handling, logging, caching, retries, mocking, and more. I spent hours making them work, so I created an app to automate integrations. Currently, the platform offers the following functionality: - Set up services with multiple endpoints: Configure caching, retries, mocking, response transformation, and fallback responses. - Define authentication:- Real-time Swagger/OpenAPI integration: Test your endpoints directly in the browser. - Handy code snippets: Easily copy and paste requests. Feedback needed!

    2025 · api200.co · its alternatives →

12. 12
    MockAPI Dog▲122

    Instant mock REST & LLM APIs - free, no signup required

    Feb 2026 · mockapi.dog · its alternatives →

13. 13
    Platapi▲108

    Convert OpenAPI docs to working dynamic mock endpoints

    2024 · its alternatives →

14. 14
    create-api.dev by Kong▲150

    Generate and share OpenAPI specs with AI

    2025 · api.dev · its alternatives →

15. 15
    Instant API – Build type-safe web APIs with JavaScript▲102

    Hey there HN! I just wrapped up an all-day documentation spree for Instant API, a JavaScript framework for easily building web APIs that implements type safety at the HTTP interface. It uses a function-as-a-service approach combined with a slightly modified JSDoc spec to automatically enforce parameter and schema validation before HTTP requests make it through to your code. You just write comments above your endpoint functions and voila, enforced type safety contracts between your API endpoints and your developers. OpenAPI specifications are generated automatically as a byproduct of simply…

    2023 · github.com · its alternatives →

16. 16
    We built a tool that automatically generates API tests▲108

    Hi, this is Mish and Sebastian. We are working on Step CI - a fully automated API testing platform for developers. Step CI works programming-language independent and for different API paradigms (REST, GraphQL, XML). Our CLI and test runner are available on GitHub (https://github.com/stepci) under the MPLv2 license. Since our last launch, Step CI is now able to generate automated tests for your API based on your OpenAPI (Swagger) spec. This saves you a lot of time as you never have to write and maintain your tests again! We would like to invite you to try our tool and give us…

    2022 · stepci.com · its alternatives →

17. 17
    Web App for generating mocked data from an OpenAPI specification▲19

    Progressive Web App for generating mocked data from an OpenAPI specification - Fredx87/openapi-mock-generator

    2020 · github.com · its alternatives →

18. 18
    AI-Powered Mock API Generator▲86

    Generate customized, realistic mock data & APIs, via GPT

    2023 · its alternatives →

19. 19
    Mocktail – Free, open-source mock API server with a built-in dashboard▲25

    Hi HN, I built the first version of Mocktail years ago. I recently came back to the project, and after a pretty substantial rebuild, v4 is now out. Mocktail is a free and open-source, self-hosted mock API server with a built-in dashboard and database, packaged as a single ~25 MB binary. You can run it locally or on your own infrastructure — no account or hosted service required. You can define endpoints and responses, generate realistic data per request, customize headers, status codes and latency, and inspect incoming requests in real time. With v4, I also added MCP support, so coding…

    Aug 2026 · getmocktail.com · its alternatives →

20. 20AG
    Auto-generate load tests/synthetic test data from OpenAPI spec/HAR file▲33

    Hey HN, We just shipped a new AI-powered feature... BUT the "AI" piece is largely in the background. Instead of relying on a chatbot, we've integrated AI (with strict input & output guardrails) into a workflow to handle two specific tasks that would be difficult for traditional programming: 1. Identifying the most relevant base URL from HAR files, since it would be tedious to cover every edge case or scenario to omit analytics, tracking, and other network noise. 2. Generating synthetic data for API requests by passing the API context and faker-js functions to GPT-4. The steps are broken down…

    2024 · docs.multiple.dev · its alternatives →

21. 21MS
    Mocktastic – Simple, Offline mock REST APIs for your entire team▲43

    2018 · mocktastic.com · its alternatives →

22. 22
    TestMagic▲53

    AI-powered API test automation. Save 90% of testing time

    2025 · irual.me · its alternatives →

23. 23
    New way to test APIs with OpenAPI and Postman▲80

    Port OpenAPI Specs to Postman Collections, inject test suite and run via Newman 👨🏽‍🚀 - apideck-libraries/portman

    2021 · github.com · its alternatives →

24. 24
    Mock Server▲4

    Swagger to Mock Backend Instantly. Build Faster with AI.

    Jan 2026 · its alternatives →

Ranked by how close each launch is in meaning, then by votes. Prices were read from each product’s own site when checked and can change. Refine with your own description →