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Top 23 Java open-source Projects
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Project mention: How to secure a Vert.x client application with CAS (using pac4j) | dev.to | 2026-09-29
The CAS server handles the login page and authenticates the user. It can be the Apereo server already used by your organization, or the public pac4j test server we'll use below.
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AppSignal
AppSignal knows why the f*#k it crashed. Stop vibe-debugging. Every exception, every backtrace, grouped so you see patterns, not noise.
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swagger-core
Examples and server integrations for generating the Swagger API Specification, which enables easy access to your REST API
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Ant-Media-Server
Ant Media Server — Ultra-low latency streaming engine with WebRTC (~0.5s), SRT, RTMP, HLS, CMAF, adaptive bitrate, transcoding & scaling
Community Edition Zip file can be downloaded from here directly
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Shelter
A Free and Open-Source (FOSS) app that leverages the "Work Profile" feature of Android to provide an isolated space that you can install or clone apps into.
Project mention: MuMu Player (NetEase) silently runs 17 reconnaissance commands every 30 minutes | news.ycombinator.com | 2026-02-19It seems that the repository has moved to https://gitea.angry.im/PeterCxy/Shelter/.
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OpenBoard
100% foss keyboard based on AOSP, with no dependency on Google binaries, that respects your privacy.
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(I haven't updated my copy of the Twitter image regex for the rename because I haven't seen any X.com image links and upstream seems dead)
‡: https://github.com/TrianguloY/URLCheck
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soapui
SoapUI is a free and open source cross-platform functional testing solution for APIs and web services.
公式サイト: https://www.soapui.org/
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linstor-server
High Performance Software-Defined Block Storage for container, cloud and virtualisation. Fully integrated with Docker, Kubernetes, Openstack, Proxmox etc.
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Slimefun4
Slimefun 4 - A unique Spigot/Paper plugin that looks and feels like a modpack. We've been giving you backpacks, jetpacks, reactors and much more since 2013.
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DSpace
(Official) The DSpace digital asset management system that powers your Institutional Repository
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Project mention: openkoda VS Hyperiux Vault - a user suggested alternative | libhunt.com/r/openkoda | 2026-09-11
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valkey-glide
An open source Valkey client library that supports Valkey, and Redis open source 6.2, 7.0 and 7.2. Valkey GLIDE is designed for reliability, optimized performance, and high-availability, for Valkey and Redis OSS based applications. GLIDE is a multi language client library, written in Rust with programming language bindings, such as Java and Python
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steady
Analyses your Java applications for open-source dependencies with known vulnerabilities, using both static analysis and testing to determine code context and usage for greater accuracy. https://eclipse.github.io/steady/
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NOTE:
The open source projects on this list are ordered by number of github stars.
The number of mentions indicates repo mentiontions in the last 12 Months or
since we started tracking (Dec 2020).
Java open-source discussion
Java open-source related posts
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OrcFlows: AI workflow automation that doesn't break at 3 a.m.
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openkoda VS Hyperiux Vault - a user suggested alternative
2 projects | 11 Sep 2026 -
Show HN: Fail the Build on Direct Service Calls
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Compiler as Custodian
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Temporal.io is the AGENTS.MD you needed all along
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MuMu Player (NetEase) silently runs 17 reconnaissance commands every 30 minutes
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Introducing temporal-contract: Type-Safe Temporal. io Workflows for TypeScript
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A note from our sponsor - SaaSHub
www.saashub.com | 9 Oct 2026
Index
What are some of the best open-source open-source projects in Java? This list will help you:
| # | Project | Stars |
|---|---|---|
| 1 | cas | 11,382 |
| 2 | swagger-core | 7,530 |
| 3 | Ant-Media-Server | 4,741 |
| 4 | Shelter | 3,643 |
| 5 | audiveris | 2,859 |
| 6 | Omni-Notes | 2,804 |
| 7 | OpenBoard | 2,736 |
| 8 | URLCheck | 2,084 |
| 9 | android-demos | 1,987 |
| 10 | soapui | 1,714 |
| 11 | linstor-server | 1,296 |
| 12 | Slimefun4 | 1,131 |
| 13 | DSpace | 1,099 |
| 14 | openkoda | 1,033 |
| 15 | personalDNSfilter | 948 |
| 16 | X-Road | 861 |
| 17 | valkey-glide | 793 |
| 18 | News-Android-App | 766 |
| 19 | ContentBlocker | 761 |
| 20 | countly-sdk-android | 696 |
| 21 | SAP Machine | 625 |
| 22 | megit | 560 |
| 23 | steady | 547 |
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Stop vibe-debugging. Every exception, every backtrace, grouped so you see patterns, not noise.
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