Open source. Open possibilities.

OpenRefine is a Java-based open-source power tool designed for cleaning, transforming, and reconciling messy data through a web browser interface.

This is a curated collection of excellent Java open-source projects, covering AI frameworks, practical projects, system design, utility libraries, and development tools, aiming to provide Java developers with high-quality learning resources and technical references.

Code随想录 (LeetCode-Master) is a structured LeetCode study plan covering data structures and algorithms, with 200+ curated problems, detailed图文 solutions, and video lectures, supporting C++、Java、Python and other languages.

Stirling PDF is an open-source PDF platform for editing, signing, converting, and automating PDFs locally or on your own servers—no external services required.

Provides an MCP server that fetches and analyzes Kotlin/Java library sources from Maven/Gradle, exposing API signatures, KDoc, source code, dependencies, and version listings via a set of tools for AI assistants and IDEs.

A collection of design patterns implemented in Java, with well-commented source code examples that serve as practical tutorials for each pattern.

JavaGuide is a systematic knowledge base for Java backend developers and interviewees, covering Java fundamentals, collections, concurrency, JVM, databases, distributed systems, system design, and AI application development, while providing learning roadmaps and interview preparation advice.

Comprehensive guide covering vast tech areas, helping professionals and students gain knowledge and resolve doubts for tech careers.

A knowledge refresher project for internet Java engineers, systematically organizing interview and practical knowledge across 5 core backend architecture fields: high-concurrency architecture, distributed systems, high-availability architecture, microservice architecture, and massive data processing.