Top 12 Java Openapi3 Projects

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1. openapi-generator

   1 257 24,676 9.9 Java

   OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec (v2, v3)

   

   Project mention: Always Up-to-Date API Docs Are Real (And No, It’s Not AI) | dev.to | 2025-08-15

   Generate TypeScript clients automatically

2. InfluxDB

   www.influxdata.com featured

   InfluxDB – Built for High-Performance Time Series Workloads. InfluxDB 3 OSS is now GA. Transform, enrich, and act on time series data directly in the database. Automate critical tasks and eliminate the need to move data externally. Download now.

   

3. swagger-core

   2 6 7,449 8.7 Java

   Examples and server integrations for generating the Swagger API Specification, which enables easy access to your REST API

   

   Project mention: OpenAPI + Swagger UI with Micronaut Application | dev.to | 2024-12-28

   To use the Swagger Annotations or Micronaut OpenAPI annotations add them to compile classpath

4. typespec

   3 22 5,341 9.9 Java

   

   Project mention: Dev Proxy v0.27: New API Modeling and AI Features Released | dev.to | 2025-05-08

   One major addition is the capability to generate TypeSpec definitions from intercepted requests. This feature allows developers to quickly create TypeSpec definitions from real traffic, streamlining the API modeling process. It works similarly to generating OpenAPI specifications, enhancing productivity.

5. springdoc-openapi

   4 21 3,512 9.6 Java

   Library for OpenAPI 3 with spring-boot

   

   Project mention: Energy-Efficient Schema-Driven Development with Spring WebMVC/WebFlux | dev.to | 2025-04-20

   In Spring WebMVC/WebFlux, you can use springdoc-openapi to automatically generate an OpenAPI schema from Spring controller implementations. Having an OpenAPI schema enables automatic generation of HTML documentation and client code, which already provides some value.

6. microcks

   5 1 1,687 9.6 Java

   The open source, cloud native tool for API Mocking and Testing. Microcks is a Cloud Native Computing Foundation sandbox project 🚀

   

   Project mention: AI-Enhanced Mock APIs with Docker Model Runner and Microcks | dev.to | 2025-05-26

   git clone https://github.com/microcks/microcks --depth 1

7. openapi-diff

   6 3 972 8.9 Java

   Utility for comparing two OpenAPI specifications.

   

8. swagger-petstore

   7 19 303 7.8 Java

   

   Project mention: MCP explained without hype or fluff | news.ycombinator.com | 2025-05-22

   OpenAPI definitions are verbose and exhaustive. In MCPs you can remove a lot of extra material, saving tokens.

   For example in [1], whole `responses` schema can be eliminated. The error texts can instead be surfaced when they appear. You also don't need duplicate json/xml/url-encoded input formats.

   [1] https://github.com/swagger-api/swagger-petstore/blob/master/...

9. Sevalla

   sevalla.com featured

   Deploy and host your apps and databases, now with $50 credit! Sevalla is the PaaS you have been looking for! Advanced deployment pipelines, usage-based pricing, preview apps, templates, human support by developers, and much more!

   

10. znai

    8 5 276 8.9 Java

    Build functional, maintainable, beautiful User Guides with markdown and Znai plugins. Instant pages navigation. Local search. Multiple integrations to work with Python, Java, C++, OpenAPI, etc. Transform "getting started" sections into slideshow for your workshops. Manage multiple documentations with self-deployed znai hub.

    

11. tcases

    9 1 233 7.8 Java

    A model-based test case generator

    

12. docserver

    10 3 5 0.0 Java

    Merge and Serve OpenAPI/Swagger Documents

    

13. spring-boot-freemarker-java-mail-api

    11 1 4 1.8 Java

    POC that sends emails to user on account creation event occurrence: made using java spring boot, apache freemarker, java-mail-API, bootstrap email editor and spring events.

    

14. spring-web-flux-todo-app

    12 1 3 0.0 Java

    Todo Application with Cloud gateway & Config server

    

Java Openapi3 related posts

• Programming in D: Tutorial and Reference

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• Energy-Efficient Schema-Driven Development with Spring WebMVC/WebFlux

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• ez-api – API development toolkit powered by TypeSpec

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• After 3 Years, I Failed. Here's All My Startup's Code

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• How to "serve" portfolio for test engineer

  1 project | dev.to | 10 Nov 2024

• Ask HN: How do you write OpenAPI docs?

  1 project | news.ycombinator.com | 9 Oct 2024

• TypeSpec

  1 project | news.ycombinator.com | 20 Sep 2024
• A note from our sponsor - SaaSHub
  www.saashub.com | 31 Aug 2025

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Sponsored

InfluxDB – Built for High-Performance Time Series Workloads

InfluxDB 3 OSS is now GA. Transform, enrich, and act on time series data directly in the database. Automate critical tasks and eliminate the need to move data externally. Download now.

www.influxdata.com

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