Rankings

Spring Boot: The de facto Java application bootstrap framework used by millions of enterprise teams

Google's Guava: The Java utility library that ships inside nearly every enterprise codebase

Animated, multi-language data structures and algorithms textbook with 127K+ GitHub stars and growing global reach

94k-star Java design patterns reference: the most-starred Java learning repo on GitHub

Self-hosted PDF platform with 50+ tools, REST API, and enterprise features — no cloud required

Elasticsearch: the distributed search engine that became infrastructure for a generation of applications

NSA's open-source reverse engineering framework challenges proprietary tools with full decompilation and scripting

Spring Framework: The foundational Java enterprise platform still powering millions of production applications

DBeaver: A mature, widely-used desktop SQL client supporting 100+ databases with a freemium model

RxJava 4.x modernizes reactive programming for the JVM with Virtual Thread and Java Flow API support

Netty: Java's foundational async network framework powering critical infrastructure for 15+ years

Selenium remains the foundational standard for browser automation, now 20+ years in production

Apache Kafka: the de facto standard for high-throughput distributed event streaming at enterprise scale

Apache Flink: Mature, production-hardened stream and batch processing engine trusted at massive scale

Alibaba's battle-tested microservice traffic control library now open to the wider Java ecosystem

OpenJDK: The reference open-source Java Development Kit powering most Java deployments worldwide

HikariCP: The de-facto default JDBC connection pool for the Java ecosystem

Chinese e-commerce reference platform with 84K stars serves as a Spring Boot learning showcase and starter kit

Chinese-language Java backend interview knowledge base with ~79K stars and broad distributed systems coverage

Termux brings a real Linux shell environment to Android, enabling developer workflows on mobile hardware