Open Source Projects using Java
A curated collection of the 94 best open source software using Java. Find the most popular and trending open source projects to learn from, contribute to, or use in your own projects.
Open-source localization platform for multilingual apps
Stars
4,146Last commit
7 hours agoLicense
Apache-2.0
Manage app translations with in-context editing, AI translation, and collaborative tools. Self-hostable and free to start.
Open Source Alternative to:
Free 2D and 3D game engine for cross-platform projects
Stars
119,299Last commit
6 hours agoLicense
MIT
Build 2D, 3D, and XR games with a full-featured engine that includes its own scripting language, scene editor, and export tools for multiple platforms.
Open Source Alternative to:
Self-hosted uptime monitoring with a clean dashboard
Stars
93,107Last commit
3 hours agoLicense
MIT
Monitors websites, APIs, and services with real-time alerts, a status page, and support for dozens of notification channels. Self-hosted and Docker-friendly.
Open Source Alternative to:
The leading distributed search and analytics engine
Stars
78,417Last commit
3 hours agoLicense
Unknown
Elasticsearch is an open-source, RESTful search engine designed for scalability, reliability, and easy management.
Open Source Alternative to:
AI workspace for docs, projects, and wikis you control
Stars
78,002Last commit
3 days agoLicense
AGPL-3.0
Open source collaborative workspace combining notes, databases, and AI with full data ownership, offline support, and self-hosting options.
Open Source Alternative to:
Docs, whiteboards, and databases in one privacy-first workspace
Stars
73,998Last commit
4 days agoLicense
MIT
An open-source, local-first knowledge base that merges structured docs, infinite whiteboards, databases, and AI into a single workspace for teams and creators.
Open Source Alternative to:
An independent browser engine built from scratch, not a fork
Stars
66,767Last commit
3 hours agoLicense
BSD-2-Clause
Open source web browser with its own engine, built from scratch without Blink, WebKit, or Gecko. Non-profit backed, no search deals, no user monetization.
Open Source Alternative to:
Open-source UI design and prototyping for product teams
Stars
61,880Last commit
3 hours agoLicense
MPL-2.0
Design, prototype, and hand off to developers in one platform. Supports design systems, tokens, flexible layouts, and AI workflows with real CSS/HTML output.
Open Source Alternative to:
Encrypted note-taking that syncs across all your devices
Stars
56,949Last commit
7 hours agoLicense
Unknown
Cross-platform note-taking app with end-to-end encryption, Markdown support, web clipping, and sync via Dropbox, OneDrive, or Joplin Cloud.
Open Source Alternative to:
Lightning-fast analytics for massive datasets
Stars
50,677Last commit
3 hours agoLicense
Apache-2.0
High-performance columnar OLAP database system for real-time analytics on big data, with SQL support and linear scalability.
Open Source Alternative to:
Free database manager for SQL databases and beyond
Stars
52,251Last commit
4 hours agoLicense
Apache-2.0
Cross-platform database management tool for exploring, editing, and querying SQL databases including MySQL, PostgreSQL, SQLite, MariaDB, and more.
Open Source Alternative to:
Privacy-first knowledge base that connects your notes
Stars
45,428Last commit
5 hours agoLicense
AGPL-3.0
Local-first, open-source knowledge management tool with bidirectional linking, outlines, flashcards, PDF annotations, and whiteboards for building a connected second brain.
Open Source Alternative to:
Open-source coding agent for your IDE and terminal
Stars
36,373Last commit
13 hours agoLicense
Apache-2.0
Runs source-controlled AI checks on every pull request, enforcing your engineering standards as native GitHub status checks with suggested fixes.
Open Source Alternative to:
Empower your team to build custom internal tools rapidly
Stars
41,139Last commit
3 hours agoLicense
Apache-2.0
Low-code platform for creating powerful internal tools and dashboards with drag-and-drop ease, robust integrations, and customizable workflows.
Open Source Alternative to:
Local AWS emulator with no account, gates, or paid tiers
Stars
27,359Last commit
3 hours agoLicense
MIT
Run AWS services locally in development and CI without an account, quotas, or feature restrictions. MIT licensed, no telemetry.
Open Source Alternative to:
Secure authentication and access control made simple
Stars
37,615Last commit
3 hours agoLicense
Apache-2.0
Comprehensive open source identity management solution offering single sign-on, social login, and fine-grained authorization for applications and services.
Open Source Alternative to:
Your personal distributed filesystem
Stars
39,348Last commit
18 days agoLicense
Apache-2.0
A cross-platform file manager that unifies your devices into a seamless, organized digital workspace.
Open Source Alternative to:
Open source AI coding agent for the terminal and IDE
Stars
28,839Last commit
3 hours agoLicense
Apache-2.0
Terminal-based AI coding agent that reads your codebase, edits files and runs commands, with support for Qwen, OpenAI, Anthropic, Gemini and local models.
Open Source Alternative to:
AI second brain for research, automation, and personal agents
Stars
37,907Last commit
3 months agoLicense
AGPL-3.0
Self-hostable AI assistant that connects to your docs and the web, lets you build agents, schedule automations, and run research with verifiable citations.
Open Source Alternative to:
Advanced vulnerability detection and management platform
Stars
32,473Last commit
6 hours agoLicense
MIT
Monitor infrastructure for exploitable vulnerabilities with real-time detection, automated workflows, and zero false positives.
Open Source Alternative to:
AI-powered code completion for seamless development
Stars
33,923Last commit
4 months agoLicense
Apache-2.0
Self-hosted AI coding assistant that enhances productivity with context-aware suggestions and privacy-focused implementation.
Open Source Alternative to:
Secure access management for modern IT infrastructure
Stars
31,861Last commit
7 hours agoLicense
GPL-3.0
Open-source privileged access management solution offering secure, browser-based access to SSH, RDP, Kubernetes, databases and remote applications.
Open Source Alternative to:
Secure, private photo storage and sharing solution
Stars
29,771Last commit
5 hours agoLicense
AGPL-3.0
End-to-end encrypted cloud storage for photos and videos, offering privacy, security, and seamless cross-device syncing.
Open Source Alternative to:
Transform natural language into SQL queries with AI
Stars
28,347Last commit
2 days agoLicense
Apache-2.0
AI-powered SQL client that converts natural language to SQL queries. Supports MySQL, Redis, MongoDB with Text2SQL, BI dashboards, and secure database management.
Open Source Alternative to:
Declarative workflow orchestration for data, AI, and infra
Stars
Stars growing over the last 30 days30,083Last commit
6 hours agoLicense
Apache-2.0
YAML-based orchestration platform with 1400+ plugins for running data pipelines, AI workflows, and infrastructure automation across teams at scale.
Open Source Alternative to:
Private, secure video calls with no account needed
Stars
30,167Last commit
3 hours agoLicense
Apache-2.0
Host encrypted video conferences directly in your browser, deploy on your own servers, or integrate into applications - all with this powerful open source platform.
Open Source Alternative to:
Private messaging with end-to-end encryption
Stars
29,559Last commit
3 hours agoLicense
AGPL-3.0
Secure messaging app with state-of-the-art encryption, voice/video calls, group chats, and file sharing. No ads, trackers, or data collection.
Open Source Alternative to:
Time-series database and historian for industrial data
Stars
25,179Last commit
11 hours agoLicense
AGPL-3.0
High-performance time-series database with industrial data management, built-in stream analytics, and AI-driven anomaly detection for operational environments.
Open Source Alternative to:
Distributed tracing, metrics, logs, and GenAI monitoring in one
Stars
24,983Last commit
19 hours agoLicense
Apache-2.0
Open source observability platform covering distributed tracing, metrics, logs, profiling, and LLM cost tracking across 10+ languages with eBPF support on Kubernetes.
Open Source Alternative to:
Open-source data integration for modern teams
Stars
22,291Last commit
3 hours agoLicense
Elastic-2.0
Seamlessly sync data from any source to any destination with a flexible, extensible platform that grows with your data needs.
Open Source Alternative to:
Full-featured media center for your TV and beyond
Stars
21,401Last commit
3 hours agoLicense
Unknown
Plays videos, music, TV shows, photos, and games from a single interface, with live TV, PVR recording, and broad format support across devices.
Open Source Alternative to:
Task manager with time tracking, focus mode, and deep work tools
Stars
Stars growing over the last 30 days23,286Last commit
3 hours agoLicense
MIT
Privacy-first task manager combining task lists, Kanban, Pomodoro timers, time tracking, and integrations with GitHub, GitLab, and Jira. No account required, works offline.
Open Source Alternative to:
Serverless Postgres for modern applications
Stars
23,286Last commit
2 months agoLicense
Apache-2.0
Cloud-native, auto-scaling Postgres with instant branching, bottomless storage, and pay-per-use pricing
Open Source Alternative to:
Scalable open-source distributed storage system
Stars
17,184Last commit
5 hours agoLicense
Unknown
Ceph provides unified object, block, and file storage from a single cluster built on commodity hardware.
Open Source Alternative to:
High-performance API gateway with built-in LLM support
Stars
17,275Last commit
16 hours agoLicense
Apache-2.0
Apache APISIX is an open-source API gateway built on NGINX and etcd, offering dynamic routing, 100+ plugins, load balancing, authentication, and traffic management for APIs and LLM workloads.
Open Source Alternative to:
Professional audio editing made simple and free
Stars
18,881Last commit
6 hours agoLicense
Unknown
Free, open-source audio editor and recorder for all platforms. Record, edit, mix and enhance audio with professional tools. Perfect for music, podcasts, and more.
Open Source Alternative to:
SQLite-compatible database for scalable multi-tenant applications
Stars
17,302Last commit
14 days agoLicense
MIT
Turso provides a simple developer experience with SQLite compatibility, allowing you to build and scale multi-tenant applications with unlimited databases.
Open Source Alternative to:
Privacy-first offline maps for hiking, cycling & navigation
Stars
15,826Last commit
3 hours agoLicense
Apache-2.0
Free, open-source offline maps app with detailed trails, turn-by-turn navigation, and zero tracking. Perfect for hikers, cyclists, and travelers seeking privacy.
Open Source Alternative to:
Visual database for workflow automation across apps
Stars
15,658Last commit
2 months agoLicense
AGPL-3.0
AITable.ai offers a visual database platform that simplifies workflow automation and connects to over 6,000 apps through integrations like Zapier and Make.
Open Source Alternative to:
Open-source search and analytics at enterprise scale
Stars
13,936Last commit
11 hours agoLicense
Apache-2.0
Community-driven, Apache 2.0-licensed search and analytics suite for ingesting, searching, visualizing, and analyzing data at scale with AI/ML capabilities.
Open Source Alternative to:
High-performance time-series database for massive data scale
Stars
17,486Last commit
3 hours agoLicense
Apache-2.0
Open-source time-series database offering massive ingestion throughput, millisecond queries, and SQL extensions, designed for optimal performance at any hardware scale.
Open Source Alternative to:
Zero-knowledge encrypted notes that sync across all devices
Stars
14,860Last commit
11 hours agoLicense
GPL-3.0
End-to-end encrypted note-taking app with zero-knowledge architecture, cross-device sync, web clipper, and a self-hostable sync server.
Open Source Alternative to:
InfluxDB – The purpose-built time series platform for high-velocity ingestion and real-time queries at scale.
Stellar Hosted
Sent
Openlane