DoppelAPI

What it does

Frontend developers often face a common bottleneck: waiting for the backend API to be ready. DoppelAPI solves this by instantly creating a "Digital Twin" of your future backend directly from your OpenAPI (Swagger) definition. Unlike traditional mock servers that return static, repetitive data, DoppelAPI uses AI-driven data generation to serve realistic, schema-compliant responses (emails, UUIDs, avatars, etc.) on the fly. It feels like interacting with a real production database.

The digital twin of your backend. Instant OpenAPI mock server with smart data generation, hot reload, and visual dashboard. - GitHub - sametuca/doppelapi: The digital twin of your backend. Instant OpenAPI mock server with smart data generation, hot reload, and visual dashboard.

DoppelAPI is a powerful CLI tool that instantly converts your OpenAPI (Swagger) definition into a fully functional, intelligent mock server. It is designed to solve the age-old problem in software development: Frontend developers waiting for backend APIs to be implemented. With DoppelAPI, you create a "Digital Twin" of your future backend. It reads your API contract (OpenAPI file) and spawns a server that behaves exactly like the real thing—populating responses with realistic, smart data automatically. DoppelAPI doesn't just serve static files. It understands your OpenAPI schema and generates data on the fly . Knowing what to send to an API is half the battle. DoppelAPI removes the…from github.com

• 
  A faster way to prototype your APIs using OpenAPI 3 and Swagger UI2020 · github.com · ▲77

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

• 
  InterimAPI2022 · interimapi.com · ▲68

  Custom API endpoints with realistic fake data in seconds

• 
  Prism2023 · stoplight.io · ▲79

  Accelerate API development with realistic mock servers

• 
  OpenAPI mocks that don't suck – realistic test data, quick setup2025 · beeceptor.com · ▲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…

• 
  Mockoon – mock REST APIs in seconds2017 · mockoon.com · ▲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.

• 
  API 2002025 · api200.co · ▲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!

• 
  /dev/null▲490

  a social network for devs

  Dev tools · 4d ago · dev-null.sh

• 
  Whiteboard (YC W26) – an open-source IDE for thoughtful software design▲423

  open-source IDE for thoughtful software design. Contribute to devdotfast/whiteboard development by creating an account on GitHub.

  Dev tools · 28d ago · github.com

• 
  Reladraw – A diagram language where you decide where to place things▲411

  Contribute to reladraw/reladraw development by creating an account on GitHub.

  Dev tools · 26d ago · github.com

• 
  OpenBot▲362

  Grok Bot alternative: free, local, open-source, multiplayer

  Dev tools · 24d ago · openbot.run

• 
  Talanoa▲346

  Hi HN, I’m a fullstack developer, and honestly, I’ve lost count of how many side projects I’ve worked on over the years. But one idea kept coming back to me: a different kind of email client. It first came to me in 2014: “What if we could handle emails more like conversations?” Every year, I’d revisit this concept in my “Build Notes.” Ten years later, no one had built exactly what I had in mind — so I finally decided to do it myself. That’s how Talanoa was born. I wanted something focused on people, not timelines. I was tired of marking messages as unread just to remember to reply later, or…

  Dev tools · 21d ago · talanoa.email

• 
  CoreSpeed▲332

  One MCP for everything your agents need: apps, memory, tools

  Dev tools · 29d ago · corespeed.io

• 
  Rork Max▲1,428

  Best AI for iOS apps. Website that replaces Xcode

  Life & fun · Feb 2026 · rork.com

• 
  happycapy▲1,365

  The agent-native computer, for the rest of us

  AI · Feb 2026 · happycapy.ai

• 
  SuperX▲897

  All-in-one growth OS for serious 𝕏 creators

  AI · Feb 2026 · superx.so

• 
  KiloClaw▲868

  Hosted OpenClaw. No Mac mini required.

  Dev tools · Feb 2026 · kilo.ai

• 
  Lovon AI Therapy▲801

  Feel closer and have more fun with your partner every day!

  AI · Feb 2026 · lovon.app

• 
  I spent 3 years reverse-engineering a 40 yo stock market sim from 1986▲721

  Hello my name is Ben Ward for the past 3 years I have been remastering the financial game Wall Street Raider created by Michael Jenkins originally on DOS in 1986. It has been a rough journey but I finally see the light at the end of the tunnel. I just recently redid the website and thought maybe the full story of how this project came to be would interest you all. Thank you for reading.

  Work · Feb 2026 · wallstreetraider.com