explaingit

Popular Java repositories on GitHub, each explained for non-coders — what it does, its tech stack, and how to run it.

• snailclimb/javaguideChinese-language interview prep guide for Java back-end developers, covering fundamentals, databases, distribu
• krahets/hello-algoAn open-source, free interactive book teaching data structures and algorithms to beginners using animated diag
• growinggit/github-chinese-top-chartsCurated leaderboards of the best Chinese-language projects on GitHub, organized by programming language and up
• iluwatar/java-design-patternsA large collection of real, runnable Java examples for classic software design patterns — from creational to b
• macrozheng/mallA complete Java e-commerce platform with customer storefront and admin back-office, built with Spring Boot, My
• spring-projects/spring-bootSpring Boot is a Java framework that sets up a production-ready Spring application with sensible defaults and
• doocs/advanced-javaChinese-language reference guide covering advanced Java backend concepts: message queues, caching, databases,
• elastic/elasticsearchA distributed, RESTful search engine designed to run across multiple servers, handling large datasets and fast
• misterbooo/leetcodeanimationAnimated visual explanations of LeetCode algorithm problems with step-by-step GIFs showing how solutions work,
• nationalsecurityagency/ghidraGhidra is a free, open-source reverse engineering tool from the NSA that lets you analyze compiled programs —
• thealgorithms/javaA collection of classic algorithms and data structures implemented in readable Java code — built for learning
• kdn251/interviewsA study guide for software engineering interviews with explanations of data structures, algorithms, and Java i
• spring-projects/spring-frameworkSpring Framework is the foundational Java platform for building large-scale enterprise applications. It elimin
• termux/termux-appTermux is a free Android app that gives your phone a real Linux terminal and package manager, letting you inst
• google/guavaGuava is Google's battle-tested open-source Java utility library that fills gaps in the standard library — add
• dbeaver/dbeaverFree desktop app that connects to over 100 different databases — MySQL, PostgreSQL, SQLite, Oracle, and more —
• skylot/jadxA tool that converts compiled Android APK files back into readable Java or Kotlin source code, letting you exa
• reactivex/rxjavaA Java library for handling streams of data and events that arrive over time — like network responses or user
• jeecgboot/jeecgbootAI-powered low-code platform that auto-generates enterprise Java applications from plain-language descriptions
• apache/dubboApache Dubbo is a Java framework that lets separate services in a large application call each other over a net
• halo-dev/haloHalo is a self-hosted, open-source website builder and CMS that powers blogs, knowledge bases, company sites,
• philjay/mpandroidchartA Java library for Android that adds interactive charts — line, bar, pie, candlestick, and more — to your app
• teamnewpipe/newpipeNewPipe is a free, open-source Android app for watching YouTube, SoundCloud, Bandcamp, and PeerTube without ad
• eugenp/tutorialsA collection of hundreds of small, runnable Java and Spring code examples organized by topic, designed to teac
• alibaba/arthasArthas is a Java diagnostic tool from Alibaba that attaches to a running application without restarting it, le
• ashishps1/awesome-system-design-resourcesCurated collection of free learning materials for studying system design—how to build large-scale software tha
• yunaiv/ruoyi-vue-proA ready-made Java admin dashboard framework with user login, permissions, file uploads, and optional e-commerc
• geekxh/hello-algorithmVisual algorithm and data structure guide for interview prep, with illustrated LeetCode solutions and tech com
• doocs/leetcodeA massive open-source collection of LeetCode algorithm solutions written in Java, Python, C++, Go, TypeScript,
• airbnb/lottie-androidAn Android library that plays After Effects animations as smooth vector graphics from a JSON file — designers
• bumptech/glideGlide is an Android image loading and caching library that handles fetching, resizing, and caching images from
• netty/nettyNetty is a high-performance Java framework for building servers that handle thousands of simultaneous network
• keycloak/keycloakKeycloak is an open-source identity server that handles login, multi-factor authentication, single sign-on, an
• xkcoding/spring-boot-demoA collection of 66+ working Spring Boot example modules showing Java developers exactly how to connect Spring
• seleniumhq/seleniumSelenium lets you write code that controls a web browser automatically — clicking buttons, filling forms, and
• zxing/zxingZXing is a Java library that reads barcodes and QR codes from images, supporting over a dozen formats includin
• alibaba/easyexcelJava library for reading and writing large Excel files efficiently using streaming, keeping memory usage low r
• blankj/androidutilcodeA Java library of ready-made utility functions for Android apps—date formatting, encryption, file handling, ne
• alibaba/nacosA platform by Alibaba that helps microservices find each other, share configuration settings in real time, and
• binarywang/wxjavaA Java library that makes it easy to build apps on WeChat — handling logins, messaging, payments, mini-program
• apache/kafkaApache Kafka is a distributed platform for moving millions of events per second between services reliably and
• conductor-oss/conductorConductor is an open-source workflow engine that reliably coordinates multi-step processes across distributed
• ityouknow/spring-boot-examplesA collection of hands-on Spring Boot example projects demonstrating specific features like databases, messagin
• chinabugotech/hutoolA Java utility library with hundreds of helper methods for common tasks like string handling, file I/O, HTTP r
• xuxueli/xxl-jobXXL-JOB is a distributed task scheduling framework for Java that automatically runs code on a schedule across
• yuliskov/smarttubeFree, ad-free media player for Android TV that lets you watch videos without ads, Google sign-in, or tracking—
• apolloconfig/apolloCentralized configuration management system for microservices. Edit settings in a web interface and push chang
• alibaba/canalCanal reads MySQL's change log in real time and streams every insert, update, and delete to other systems like
• alibaba/spring-cloud-alibabaA toolkit for Java developers that plugs into Spring Cloud to add service discovery, traffic control, distribu
• drklo/telegramOfficial Android source code for Telegram messaging app. Build your own Telegram-compatible client by compilin
• wuyouzhuguli/springallA collection of hands-on Java code examples for learning Spring Boot, Spring Security, Spring Cloud, and relat
• alibaba/druidDruid is a Java database connection pool library from Alibaba that reuses pre-opened database connections for
• lenve/vhrA web-based HR management system for tracking employees, departments, salaries, and payroll. Built with Spring
• anuken/mindustryMindustry is a free open-source strategy game that combines tower defense with factory automation — build conv
• crossoverjie/jcsproutA curated Chinese-language knowledge base of Java fundamentals, covering collections, multithreading, the JVM,
• kestra-io/kestraKestra is an open-source workflow automation platform where you describe multi-step processes in YAML, then sc
• qiurunze123/miaoshaEducational Java project teaching how to build a high-concurrency flash sale system that handles thousands of
• openapitools/openapi-generatorA tool that reads an API specification file and automatically generates ready-to-use code — client libraries,
• apache/flinkApache Flink is an enterprise-grade open-source framework for processing massive streams of data in real time
• apache/incubator-seataSeata keeps data consistent across multiple Java microservices that each have their own database — if any step
• alibaba/fastjsonFast Java library for converting objects to and from JSON, the standard format for web APIs and data storage.
• codephiliax/chat2dbAI-powered database client that lets you query databases using plain English instead of SQL, with support for
• hollischuang/tobetopjavaerA comprehensive Chinese-language study guide covering 500+ Java interview questions and 60,000+ words on core
• jakewharton/butterknifeButter Knife was an Android library that replaced repetitive UI wiring code with simple annotations — now offi
• bazelbuild/bazelBazel is a fast, reliable build system that only rebuilds code that actually changed, supports multiple progra
• jenkinsci/jenkinsJenkins is an open-source automation server that watches your code repository and automatically builds, tests,
• scwang90/smartrefreshlayoutAndroid library that adds pull-to-refresh and load-more gestures to lists and feeds with automatic detection o
• libgdx/libgdxlibGDX is a free Java game development framework that lets you write a game once and deploy it to Windows, Mac
• apache/skywalkingApache SkyWalking is an open-source monitoring system that collects traces, metrics, and logs from distributed
• proxyee-down-org/proxyee-downAn open-source HTTP download accelerator that acts as a local proxy to speed up file downloads by splitting th
• greenrobot/eventbusEventBus is a tiny Java and Android library that lets different parts of your app send and receive messages wi
• netflix/hystrixA Java library from Netflix that keeps distributed backend systems running when individual services fail, usin
• ibotpeaches/apktoolApktool is a reverse engineering tool for Android APK files that decodes compiled apps into readable resources
• redisson/redissonRedisson is a Java library that wraps Redis and Valkey so your application can share Maps, Sets, Queues, locks
• google/gsonGson is a Google Java library that converts any Java object to JSON and back with a single method call, even o
• dataease/dataeaseSelf-hosted business intelligence tool for building interactive data dashboards without code. Connect database
• ashishps1/awesome-low-level-designA free collection of object-oriented design problems and Java solutions to help software developers prepare fo
• lsposed/lsposedAndroid framework that lets you install modules to modify app behavior and system features at runtime without
• enterprisequalitycoding/fizzbuzzenterpriseeditionA satirical Java implementation of the FizzBuzz programming exercise using absurdly complex enterprise pattern
• doocs/source-code-hunterDeep-dive Chinese-language walkthroughs of how popular Java frameworks (Spring, MyBatis, Netty, Dubbo, Redis,
• alibaba/sentinelA Java library from Alibaba that protects backend microservices from traffic overload using rate limiting, cir
• openjdk/jdkThis is the official source code for the Java Development Kit — the compiler, runtime, and standard library th
• kunal-kushwaha/dsa-bootcamp-javaFree Java bootcamp with code, exercises, and notes for learning data structures, algorithms, and interview pre
• apache/rocketmqApache RocketMQ is a high-throughput messaging platform that reliably delivers events between services in dist
• elunez/eladminA ready-made Java admin panel starter kit with user management, role-based permissions, and a code generator t
• google/exoplayerDeprecated Android media playback library for audio and video. Development has moved to AndroidX Media3; use t
• thingsboard/thingsboardThingsBoard is an open-source IoT platform that collects data from physical devices, stores it, and displays i
• oracle/graalGraalVM is a Java toolkit that compiles applications into standalone binaries before they run, enabling instan
• carguo/gsyvideoplayerAndroid video player library with pluggable playback engines, streaming support, danmaku comments, filters, an
• brettwooldridge/hikaricpA fast, lightweight JDBC connection pool for Java applications — it manages a pool of pre-opened database conn
• apache/shardingsphereApache ShardingSphere adds a smart layer on top of your existing databases so they can scale out, shard data a
• opendataloader-project/opendataloader-pdfAn open-source Java tool that converts PDFs into structured Markdown, JSON, or HTML for AI pipelines, and adds
• didi/dokitA floating debugging panel for mobile apps that gives developers instant access to GPS spoofing, crash logs, n
• mybatis/mybatis-3A Java framework that lets you write your own SQL queries and automatically maps the results to Java objects,
• linlinjava/litemallA complete open-source online shopping mall system with backend, admin panel, WeChat Mini Program, and mobile
• yudaocode/springboot-labsA comprehensive Java learning repository with 50,000+ lines of example code covering Spring Boot, Spring Cloud
• jetbrains/intellij-communityThe open-source codebase behind IntelliJ IDEA and the IntelliJ Platform — the shared foundation for PyCharm, W
• reactivex/rxandroidA small Android library that lets you safely deliver background task results to the UI thread using RxJava — s
• lionsoul2014/ip2regionOffline IP-to-location lookup library that translates IP addresses to country, city, and ISP without network r
• dianping/catReal-time application monitoring platform that tracks errors, slow requests, and performance metrics across di
• yunaiv/yudao-cloudOpen-source enterprise backend platform with microservices, RBAC, multi-tenancy, e-commerce, and code generati
• antlr/antlr4A tool that reads grammar rules you write and automatically generates code that can parse custom languages, fi
• baseflow/photoviewAn Android library that adds pinch-to-zoom and double-tap zoom to image views with a two-line Gradle install —
• dromara/sa-tokenSa-Token is a Java library that adds login, session management, roles, permissions, single sign-on, and OAuth
• williamfiset/algorithmsA comprehensive Java library of algorithms and data structures with clear implementations and video explanatio
• tencent/apijsonA Java library that lets frontend clients query and modify databases directly via JSON requests, eliminating t
• lmax-exchange/disruptorA high-performance Java library for ultra-low-latency inter-thread communication, built by LMAX Exchange for s
• forezp/springcloudlearningChinese-language tutorial repo with runnable Java examples that teach Spring Cloud — the toolkit for building
• ben-manes/caffeineCaffeine is a Java in-memory caching library with size and time-based eviction, async refresh, and removal not
• tencent/tinkerTinker is a Tencent library that lets Android apps patch their compiled code, native libs, and resources at ru
• infinilabs/analysis-ikElasticsearch and OpenSearch plugin that adds Chinese-language tokenization via the IK analyzer, with custom a
• justauth/justauthA Java library that adds social login (GitHub, Google, WeChat, and 40+ more) to your app through a single unif
• openzipkin/zipkinZipkin collects timing data from each service in a multi-service application so you can look up exactly where
• baomidou/mybatis-plusJava toolkit that extends MyBatis with ready-made CRUD methods, pagination, a lambda query API, and a code gen
• gyoogle/tech-interview-for-developerA Korean-language encyclopedia of computer science topics for entry-level developer technical interviews, cove
• material-components/material-components-androidGoogle's official Material Design UI components library for native Android apps. Drop-in replacement for the o
• alibaba/dataxAlibaba's open-source batch data synchronization framework that moves data between databases, warehouses, and
• facebook/frescoMeta's Android library for loading and displaying images. Handles memory, two-level caching, progressive JPEGs
• itwanger/tobebetterjavaerA large free Chinese-language guide to learning Java and backend development, covering everything from Java ba
• questdb/questdbQuestDB is an open-source time-series database optimized for high-speed ingestion and fast SQL queries on time
• heibaiying/bigdata-notesA Chinese-language beginner's guide to big data. Twelve tutorial tracks covering Hadoop, Hive, Spark, Flink, K
• nostra13/android-universal-image-loaderAn archived Android Java library that loads, caches, and displays images from URLs, files, or content provider
• grasscutters/grasscutterAn unofficial private server reimplementation in Java for a certain anime game, letting players run the game l
• winterbe/java8-tutorialA short, code-first walkthrough of every new feature added in Java 8 — lambdas, streams, the new date API, and
• prestodb/prestoA distributed SQL query engine that runs analytical SQL across petabyte-scale data lakes by splitting work acr
• shuzheng/zhengZheng is a Java enterprise application framework built on Spring, SpringMVC, and MyBatis that bundles SSO, CMS
• jeffli1993/springboot-learning-exampleTutorial-style collection of Spring Boot Java code examples covering web, JPA, MyBatis, Redis, Elasticsearch,
• neo4j/neo4jGraph database that stores data as nodes and relationships instead of rows and tables. You query it with Cyphe
• ashishps1/awesome-leetcode-resourcesA hand-picked reading list of the best online resources for learning data structures and algorithms and prepar
• android-hacker/virtualxposedAn Android app that runs Xposed modules inside a virtual sandbox, so you can hook and modify other apps withou
• dyc87112/springboot-learningFree Chinese-language tutorial series for Spring Boot covering 1.x and 2.x, with example projects for MyBatis,
• quarkusio/quarkusJava framework that builds cloud-native and Kubernetes-friendly apps with fast startup, low memory, and native
• android10/android-cleanarchitectureSample Android app in Java that shows how to apply Uncle Bob Clean Architecture with presentation, domain, and
• apache/hadoopApache Hadoop is an open-source Java framework for distributed storage and batch processing of very large data
• konloch/bytecode-viewerBytecode Viewer is a Java reverse-engineering GUI that bundles six decompilers, disassemblers, and APK tooling
• mockito/mockitoMost popular Java mocking framework for unit tests. Lets you create fake versions of dependencies like databas
• apache/dorisApache Doris is an open-source analytical database that runs complex queries across billions of rows in under
• apache/pulsarApache Pulsar is a distributed messaging system — like a postal service for software — that moves millions of
• zaproxy/zaproxyZAP (Zed Attack Proxy) is a free open-source web application security scanner for finding vulnerabilities, use
• cryptomator/cryptomatorDesktop app for Windows, macOS, and Linux that encrypts your files locally before they sync to Dropbox, Google
• java-decompiler/jd-guiJD-GUI is a desktop app that decompiles Java .class and .jar files back into readable source code so you can b
• zhisheng17/flink-learningA Chinese-language learning repo with Java code samples for Apache Flink, covering connectors, concepts like w
• supertokens/supertokens-coreSuperTokens core is a self-hosted Java auth backend for login, sessions, social and passwordless flows, MFA, a
• theonedev/onedevSelf-hosted all-in-one dev platform in Java: Git hosting, code review, CI/CD with a visual editor, Kanban boar
• elastic/logstashServer-side data processing pipeline that ingests logs and events from many sources, transforms them, and ship
• eclipse-vertx/vert.xCore of the Vert.x reactive toolkit for the JVM, providing low-level HTTP, TCP, and file system APIs that othe
• arduino/arduinoSource code for the legacy Arduino IDE 1.x desktop application used to write and upload sketches to Arduino mi
• hdodenhof/circleimageviewA lightweight Android library that displays images as perfect circles — ideal for profile pictures and avatars
• tencent/qmui_androidA ready-made Java UI library for Android from Tencent that provides common interface components and a global s
• alibaba/arouterARouter is an Android routing library from Alibaba that lets modules in a large app jump to any screen using a
• languagetool-org/languagetoolLanguageTool is open-source grammar and style checking software that catches errors beyond basic spell-checkin
• googlecontainertools/jibGoogle's tool for packaging Java applications into Docker container images directly from Maven or Gradle build
• apache/dolphinschedulerAn open-source workflow scheduler for data pipelines — build, run, and monitor multi-step data tasks visually
• deeplearning4j/deeplearning4jEclipse Deeplearning4J is a suite of Java libraries for building and running AI neural network models on the J
• kekingcn/kkfileviewA self-hosted web service that previews over 100 file types—Word, Excel, PDF, images, video, CAD, 3D models, a
• xpipe-io/xpipeA desktop app that centralizes all your server, container, cloud, and VM connections in one place, letting you
• janishar/mit-deep-learning-book-pdfA clean, bookmarked PDF of the Deep Learning textbook by Goodfellow, Bengio, and Courville — the book is free
• netflix/zuulZuul is Netflix's open-source API gateway written in Java that sits in front of your web services and handles
• apache/druidApache Druid is a high-speed analytics database for querying billions of rows of real-time and historical data
• sqshq/piggymetricsPiggymetrics is a sample personal-finance app built as a teaching example to demonstrate microservice architec
• orhanobut/loggerA small Android library that replaces the default Logcat output with visually formatted log messages — borders
• pinpoint-apm/pinpointPinpoint is a self-hosted monitoring tool for large Java systems split across many services — it traces each u
• seaswalker/spring-analysisA collection of personal reading notes in Chinese that walk through how the Spring framework works internally,
• jessyancoding/androidautosizeAndroid library that automatically makes your app look correct on any phone screen size by adjusting layout sc
• lucksiege/pictureselectorAn Android library that adds a fully-featured image, video, and audio picker to your app with cropping, compre
• lgvalle/material-animationsA reference guide for Android's built-in Transition Framework with code samples and animated GIFs showing how
• tink-crypto/tinkA cryptography library from Google that makes encryption, signing, and key management easy to do safely across
• bigkoo/android-pickerviewAndroid-PickerView is a Java library that adds iOS-style scrolling wheel selectors to Android apps for picking
• projectlombok/lombokProject Lombok is a Java library that automatically generates repetitive boilerplate code like getters, setter
• macrozheng/mall-learningA structured Chinese-language tutorial series that walks Java developers through building a production-grade e
• microg/gmscoremicroG Services is a free, open-source replacement for Google Play Services that lets Android apps requiring G
• metersphere/metersphereOpen-source team testing platform covering API tests, test plans, defect tracking, and reports, with an AI ass
• pxb1988/dex2jarA toolkit that converts Android APK and DEX files into readable Java class files or smali text, making it easy
• youth5201314/bannerA Java Android library that adds a smoothly looping image carousel to your app, with built-in transition effec
• plantuml/plantumlA Java tool that turns short plain-text scripts into diagrams — UML, mind maps, Gantt charts, wireframes, and
• alibaba/colaA Java application framework from Alibaba that enforces a standard layered folder structure for backend projec
• macrozheng/mall-swarmA complete e-commerce platform built as Java microservices — covering product management, orders, search, and
• opensearch-project/opensearchAn open-source enterprise search and analytics engine that lets you index millions of documents or log events
• codecentric/spring-boot-adminA web dashboard for monitoring and managing Spring Boot Java services, showing health, memory, logs, and confi
• trinodb/trinoTrino is an open-source SQL engine that lets you query massive amounts of data across multiple databases, data
• lawnchairlauncher/lawnchairA free open-source Android home screen replacement app that adds Material 3 wallpaper-based theming, icon pack
• netflix/conductorA workflow orchestration server originally built at Netflix that sequences multi-step business processes acros
• apache/zookeeperA reliable coordination service for distributed systems that helps clusters of computers agree on shared state
• google/guiceA Google library for Java that automatically wires up the dependencies between parts of your program. You add
• debezium/debeziumA tool that watches databases for every insert, update, and delete, then streams those changes to Apache Kafka
• netflix/eurekaNetflix's service registry that lets backend services find each other on AWS without hardcoded addresses. Serv
• facebook/stethoA Facebook-built Android debugging tool that connects your running Android app to Chrome's developer tools, so
• greenrobot/greendaoAn Android database library (now unmaintained) that maps Java objects to SQLite rows so you can store and retr
• zhihu/matisseA drop-in Android library that adds a polished image and video picker screen to your mobile app, with customiz
• daimajia/androidviewanimationsAndroidViewAnimations is a Java library that lets you add over 60 ready-made visual effects to any element in
• beemdevelopment/aegisAegis is a free, open-source Android app that generates and securely stores two-factor authentication codes in
• daimajia/androidswipelayoutAn Android library that adds swipe-to-reveal hidden buttons or content to any part of your screen — works in l
• pagehelper-org/mybatis-pagehelperA Java plugin that automatically adds pagination to MyBatis database queries, supporting 20+ databases includi
• redis/jedisThe official Java library for connecting to a Redis server — add it to your Maven or Gradle project and store,
• amitshekhariitbhu/android-interview-questionsA curated collection of hundreds of Android developer interview questions and answers covering Kotlin, corouti
• papermc/paperPaper is the most widely used high-performance Minecraft server replacement, offering speed improvements, bug
• team-xmanager/xmanagerxManager is an Android app that lets you install, upgrade, or downgrade specific versions of a popular music s
• tencent/matrixWeChat's open-source performance monitoring framework for iOS and Android apps, detecting crashes, lag, memory
• langchain4j/langchain4jLangChain4j is a Java library that connects your app to over 20 AI providers and adds chat memory, document se
• tencent/vassonicA Tencent framework that makes websites load faster inside mobile apps by pre-fetching page content in paralle

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