RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.

Alibaba Java Diagnostic Tool Arthas/Alibaba Java诊断利器Arthas

Netty project - an event-driven asynchronous network application framework

Apache Flink

Redisson - Valkey and Redis Java client. Complete Real-Time Data Platform. Sync/Async/RxJava/Reactive API. Over 50 Valkey and Redis based Java objects and services: Set, Multimap, SortedSet, Map, L…

CAT 作为服务端项目基础组件，提供了 Java, C/C++, Node.js, Python, Go 等多语言客户端，已经在美团点评的基础架构中间件框架（MVC框架，RPC框架，数据库框架，缓存框架等，消息队列，配置系统等）深度集成，为美团点评各业务线提供系统丰富的性能指标、健康状况、实时告警等。

A high performance caching library for Java

Very spicy additions to the Java programming language.

Apache Tomcat

Open source version of Google Authenticator (except the Android app)

美团点评集团统一使用的MySQL数据库访问层的中间件。主要提供对业务开发透明、读写分库、分库分表能力，并提供了端到端SQL监控的集成方案。

Implementation of various string similarity and distance algorithms: Levenshtein, Jaro-winkler, n-Gram, Q-Gram, Jaccard index, Longest Common Subsequence edit distance, cosine similarity ...