SSealbook
Sealbook / Open source

The open-source projects that matter
65,712 GitHub repos with 1,000+ stars

Ranked by stars, grouped by what they do, with license and maintenance at a glance — and linked to the SaaS products they replace.

Open-source alternatives to SaaS →Validate an idea

Categories

Learning resources & lists4,138 reposAI agents & LLM apps5,147 reposMachine learning & data science4,679 reposSelf-hosted apps (SaaS alternatives)1,859 reposSecurity & hacking2,493 reposDevOps, cloud & infrastructure3,295 reposDatabases & data engineering2,010 reposWeb & backend frameworks4,712 reposFrontend, UI & design5,401 reposMobile development4,059 reposDeveloper tools, CLI & editors4,070 reposProgramming languages & runtimes501 reposDesktop & everyday apps4,082 reposGames & game engines1,051 reposBlockchain & crypto537 reposHardware, IoT & embedded887 repos

Most-starred on GitHub

RepositoryStarsLanguageLicenseActivity
1codecrafters-io/build-your-own-xMaster programming by recreating your favorite technologies from scratch.★ 554.3kMarkdown—Slowing
2sindresorhus/awesome😎 Awesome lists about all kinds of interesting topics [NOTE: Pull requests are temporarily disabled until I have a chance to catch up with t★ 520.9k—CC0-1.0Active
3public-apis/public-apisA collective list of free APIs★ 490kPythonMITActive
4freeCodeCamp/freeCodeCampfreeCodeCamp.org's open-source codebase and curriculum. Learn math, programming, and computer science for free.★ 457.4kTypeScriptBSD-3-ClauseActive
5EbookFoundation/free-programming-books:books: Freely available programming books★ 399.5kPythonCC-BY-4.0Active
6openclaw/openclawThe AI that really does things. Any OS. Any Platform. The lobster way. 🦞 ★ 392.4kTypeScriptMITActive
7donnemartin/system-design-primerLearn how to design large-scale systems. Prep for the system design interview. Includes Anki flashcards.★ 374.6kPythonOtherActive
8nilbuild/developer-roadmapInteractive roadmaps, guides and other educational content to help developers grow in their careers.★ 369.8kTypeScriptOtherActive
9jwasham/coding-interview-universityA complete computer science study plan to become a software engineer.★ 362.8k—CC-BY-SA-4.0Stale
10vinta/awesome-pythonThe definitive list that answers "I want to do X in Python, which tool should I use?"★ 328.4kPythonOtherActive
11awesome-selfhosted/awesome-selfhostedA list of Free Software network services and web applications which can be hosted on your own servers★ 328k—OtherActive
12morluto/reaReverse engineer anything with agents, from app behavior down to native binaries.★ 319.5kTypeScriptMITActive
13obra/superpowersAn agentic skills framework & software development methodology that works.★ 301.6kShellMITActive
14mattpocock/skillsSkills for Real Engineers. Straight from my .agents directory.★ 296kShellMITActive
15practical-tutorials/project-based-learningCurated list of project-based tutorials★ 287.2kPythonMITActive
16affaan-m/ECCThe agent harness performance optimization system. Skills, instincts, memory, security, and research-first development for Claude Code, Code★ 283.1kJavaScriptMITActive
17996icu/996.ICURepo for counting stars and contributing. Press F to pay respect to glorious developers.★ 277.2k—OtherStale
18NousResearch/hermes-agentThe agent that grows with you★ 254.9kPythonMITActive
19deepseek-ai/deepseek-harnessDeepSeek Harness: Everything is a Plugin.★ 253kTypeScriptMITActive
20torvalds/linuxLinux kernel source tree★ 252.4kCOtherActive
21react/reactThe library for web and native user interfaces.★ 251.3kJavaScriptMITActive
22trimstray/the-book-of-secret-knowledgeA collection of inspiring lists, manuals, cheatsheets, blogs, hacks, one-liners, cli/web tools and more.★ 251.1k—MITStale
23TheAlgorithms/PythonAll Algorithms implemented in Python★ 225.4kPythonMITActive
24multica-ai/andrej-karpathy-skillsA single CLAUDE.md file to improve Claude Code behavior, derived from Andrej Karpathy's observations on LLM coding pitfalls.★ 220.9k——Slowing
25anomalyco/opencodeThe open source coding agent.★ 216.3kTypeScriptMITActive

Rising: created in the last 12 months

RepositoryStarsLanguageLicenseActivity
1openclaw/openclawThe AI that really does things. Any OS. Any Platform. The lobster way. 🦞 ★ 392.4kTypeScriptMITActive
2morluto/reaReverse engineer anything with agents, from app behavior down to native binaries.★ 319.5kTypeScriptMITActive
3mattpocock/skillsSkills for Real Engineers. Straight from my .agents directory.★ 296kShellMITActive
4affaan-m/ECCThe agent harness performance optimization system. Skills, instincts, memory, security, and research-first development for Claude Code, Code★ 283.1kJavaScriptMITActive
5deepseek-ai/deepseek-harnessDeepSeek Harness: Everything is a Plugin.★ 253kTypeScriptMITActive
6multica-ai/andrej-karpathy-skillsA single CLAUDE.md file to improve Claude Code behavior, derived from Andrej Karpathy's observations on LLM coding pitfalls.★ 220.9k——Slowing
7ultraworkers/claw-codeAn agent-managed museum exhibit, built in Rust with Gajae-Code / LazyCodex — developed and maintained with no human intervention.★ 194.9kRustMITActive
8DietrichGebert/ponytailMakes your AI agent think like the laziest senior dev in the room. The best code is the code you never wrote.★ 166.9kJavaScriptMITActive
9nextlevelbuilder/ui-ux-pro-max-skillAn AI skill that provides design intelligence for building professional UI/UX across multiple platforms.★ 137.2kPythonMITActive
10garrytan/gstackUse Garry Tan's exact Claude Code setup: 23 opinionated tools that serve as CEO, Designer, Eng Manager, Release Manager, Doc Engineer, and Q★ 136.8kTypeScriptMITActive
11Graphify-Labs/graphifyTurn any codebase, with its docs, SQL schemas, configs, and PDFs, into a queryable knowledge graph. A /graphify skill for Claude Code, Curso★ 128.3kPythonApache-2.0Active
12VoltAgent/awesome-design-mdA collection of DESIGN.md files analysis by popular brand design systems. Drop one into your project and let coding agents generate a matchi★ 122.1k—MITActive
13JuliusBrussee/caveman🪨 why use many token when few token do trick. Viral skill + proxy for coding agents that cuts 65% of tokens by talking like a caveman.★ 113.4kGoApache-2.0Active
14addyosmani/agent-skillsProduction-grade engineering skills for AI coding agents.★ 108.1kJavaScriptMITActive
15paperclipai/paperclipThe open-source app everyone uses to manage agents at work★ 104kTypeScriptMITActive

Open-source alternatives to popular SaaS

All →
Alternatives to Zapier 3Alternatives to Webflow 2Alternatives to Algolia 1Alternatives to Retool 3Alternatives to Apollo 1Alternatives to Mixpanel 2Alternatives to Vanta 1Alternatives to Bird 1Alternatives to Heroku 4Alternatives to Supabase 1Alternatives to Plivo 1Alternatives to Canva 1Alternatives to Trello 3Alternatives to Figma 2Alternatives to Airtable 3Alternatives to Semrush 1Alternatives to MongoDB 3Alternatives to Xero 1

By language

Python 11,883JavaScript 7,784TypeScript 6,528Go 4,047Java 3,851C++ 3,404C 2,514Rust 2,415C# 1,854Shell 1,595PHP 1,549HTML 1,541Swift 1,384Jupyter Notebook 1,333Kotlin 1,039Ruby 1,004Objective-C 906CSS 590Dart 450Vue 438Lua 379PowerShell 210Vim Script 206Scala 184

Data from the GitHub API, refreshed regularly. Stars measure popularity, not quality — check the license and recent activity before you depend on a project.