Java open-source

Open-source Java projects categorized as open-source

Top 23 Java open-source Projects

open-source
  1. cas

    Apereo CAS - Identity & Single Sign On for all earthlings and beyond.

  2. InfluxDB

    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.

    InfluxDB logo
  3. swagger-core

    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. android

    📱 Nextcloud Android app

    Project mention: Nextcloud cries foul over Google Play Store app rejection | news.ycombinator.com | 2025-05-13

    > I believe the nextcloud team when they say they need the permission.

    I don't (and I do use NC). The sentence "SAF cannot be used, as it is for sharing/exposing our files to other apps" is simply wrong and llm_thread is right that SAF should be able to handle that use case,see

    https://developer.android.com/training/data-storage/shared/d...

    There are some restrictions regarding which directories you can access, but for most use-cases it should be perfectly fine. It's also not that this should come as a surprise to them. In fact, there's an issue about this from the NC team themselves from August '23:

    https://github.com/nextcloud/android/issues/10123

    Why they still think SAF cannot be used is a mystery to me.

  5. 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.

  6. Omni-Notes

    Open source note-taking application for Android

  7. OpenBoard

    100% foss keyboard based on AOSP, with no dependency on Google binaries, that respects your privacy.

  8. android-demos

    Examples of Android applications

  9. SaaSHub

    SaaSHub - Software Alternatives and Reviews. SaaSHub helps you find the best software and product alternatives

    SaaSHub logo
  10. audiveris

    Latest generation of Audiveris OMR engine

  11. soapui

    SoapUI is a free and open source cross-platform functional testing solution for APIs and web services.

    Project mention: Diving into Spring Web Services (Spring-WS): Contract-First SOAP Service Development | dev.to | 2025-04-15

    Contract Testing: Implement contract tests (e.g., using SoapUI or Spring Cloud Contract) to ensure your service stays compliant with the defined contract.

  12. URLCheck

    Android app by TrianguloY: URLCheck

    Project mention: A web extension to redirects YouTube, X, etc. to privacy-friendly front ends | news.ycombinator.com | 2025-06-21

    I just found out about an Android app where you can set up custom redirects for any links, OS-wide: https://github.com/TrianguloY/URLCheck

    It's a little finnicky to set up, but I'm enjoying it so far. It goes beyond alternative frontend redirects. You can strip URL params, check domains against a blacklist, and choose native apps to open links that match a pattern.

  13. linstor-server

    High Performance Software-Defined Block Storage for container, cloud and virtualisation. Fully integrated with Docker, Kubernetes, Openstack, Proxmox etc.

  14. 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.

  15. DSpace

    (Official) The DSpace digital asset management system that powers your Institutional Repository

    Project mention: Dublin Core, what is it good for? | news.ycombinator.com | 2024-09-01

    Dublin Core is the main metadata schema for many institutional repositories, for example the DSpace platform https://github.com/DSpace/dspace. The schema essentially only covers basic bibliographic metadata and has a strong pre-digital library feel to it. We end up augmenting with other custom schemas to be able to describe content in our repository, for example podcasts and journal articles with different issue and online dates, as well as extra metadata like author affiliations, funders, internal programs etc.

  16. openkoda

    Open source business application platform for fast development

    Project mention: Ask HN: What are you working on? (April 2025) | news.ycombinator.com | 2025-04-27

    https://github.com/openkoda/openkoda

    I am working on an open-source insurance application platform.

    The main goal is to accelarate time-to-market for insurance and insurtech innovations, providing all these "boring" enterprise features (like multitenancy, role-based security, audit trails, etc.) out of the box, so that you can focus on building the actual product.

  17. personalDNSfilter

    personalDNSfilter is a DNS filter proxy written in Java.

  18. News-Android-App

    📱🗞️ Android client for the Nextcloud news/feed reader app

  19. knime-core

    KNIME Analytics Platform

  20. countly-sdk-android

    Countly Product Analytics Android SDK

  21. X-Road

    Source code of the X-Road® data exchange layer software

  22. ContentBlocker

    Content blocking extension for Samsung Internet and Yandex Browser

  23. SAP Machine

    An OpenJDK release maintained and supported by SAP

  24. 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/

    Project mention: Eclipse Steady – Java Code Analysis | news.ycombinator.com | 2024-10-27
  25. megit

    Standalone Git GUI based on EGit

  26. SaaSHub

    SaaSHub - Software Alternatives and Reviews. SaaSHub helps you find the best software and product alternatives

    SaaSHub logo
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).

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  • A note from our sponsor - InfluxDB
    www.influxdata.com | 24 Jun 2025
    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. Learn more →

Index

What are some of the best open-source open-source projects in Java? This list will help you:

# Project Stars
1 cas 11,125
2 swagger-core 7,428
3 android 4,651
4 Shelter 2,785
5 Omni-Notes 2,746
6 OpenBoard 2,639
7 android-demos 1,992
8 audiveris 1,952
9 soapui 1,623
10 URLCheck 1,388
11 linstor-server 1,089
12 Slimefun4 1,030
13 DSpace 982
14 openkoda 967
15 personalDNSfilter 745
16 News-Android-App 719
17 knime-core 712
18 countly-sdk-android 692
19 X-Road 688
20 ContentBlocker 613
21 SAP Machine 547
22 steady 541
23 megit 468

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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.
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