Open Source Projects using CSS
A curated collection of the 629 best open source software using CSS. Find the most popular and trending open source projects to learn from, contribute to, or use in your own projects.
Turn any website into clean, AI-ready data via API
Stars
Stars growing over the last 30 days193,191Last commit
5 hours agoLicense
AGPL-3.0
API for AI agents to search, scrape, crawl, and interact with the live web, returning clean Markdown, structured JSON, or screenshots from any page.
Open Source Alternative to:
Schedule, analyze, and manage 30+ social media accounts
Stars
Stars growing over the last 30 days37,429Last commit
5 hours agoLicense
AGPL-3.0
Self-hostable social media scheduler that lets you plan, generate, and publish content across 30+ networks with AI assistance, team collaboration, and automation integrations.
Open Source Alternative to:
Multi-channel notification infrastructure for apps
Stars
40,173Last commit
16 hours agoLicense
Unknown
Open-source platform for building in-app, email, push, SMS, and chat notifications with a unified API, workflow engine, and embeddable inbox component.
Open Source Alternative to:
Self-hosted SEO platform for keyword, backlink, and rank tracking
Stars
Stars growing quickly over the last 30 days24,215Last commit
6 hours agoLicense
MIT
Manage keyword research, backlink analysis, competitor monitoring, and rank tracking without expensive SaaS subscriptions. Self-hostable, MIT-licensed, uses DataForSEO.
Open Source Alternative to:
A clean, cross-platform SQL editor for multiple databases
Stars
23,771Last commit
8 hours agoLicense
Unknown
SQL GUI client for MySQL, Postgres, SQLite, SQL Server, and more, with a spreadsheet-like data editor, AI shell, SSH tunneling, and team workspaces.
Open Source Alternative to:
Structured control layer for customer-facing AI agents
Stars
18,307Last commit
5 hours agoLicense
Apache-2.0
A conversational AI server that manages agent behavior through context-aware guidelines, keeping responses consistent, auditable, and aligned at scale.
Open Source Alternative to:
An agentic CRM that keeps records current automatically
Stars
Stars growing over the last 30 days11,532Last commit
1 month agoLicense
MIT
Open source CRM with AI agents that read your inbox, enrich contacts and companies, schedule follow-ups, and build new agents from plain-language descriptions.
Open Source Alternative to:
Passkeys, SSO, and MFA without vendor lock-in
Stars
9,043Last commit
21 hours agoLicense
Unknown
Open source authentication platform supporting passkeys, 2FA, SSO, and social login. Self-host or use Hanko Cloud, with full control over your data and no lock-in.
Open Source Alternative to:
Cookie-free web and product analytics, self-hostable
Stars
7,170Last commit
6 hours agoLicense
AGPL-3.0
Open-source analytics platform covering web traffic, custom events, funnels, retention, session replay, and revenue tracking. GDPR-compliant with optional self-hosting.
Open Source Alternative to:
Task management with GitHub sync and AI agents for devs
Stars
Stars growing over the last 30 days4,771Last commit
7 hours agoLicense
AGPL-3.0
Task manager built for engineering teams, combining status tracking, priority management, GitHub integration, and AI agents that can close tasks automatically.
Open Source Alternative to:
Keyboard-first email client with AI, chat, and tasks
Stars
Stars growing over the last 30 days4,771Last commit
7 hours agoLicense
AGPL-3.0
An AI-powered email client that combines inbox management, chat, tasks, and AI agents in one shared workspace, built for keyboard-driven workflows.
Open Source Alternative to:
Markdown docs wired into tasks, email, and agents
Stars
Stars growing over the last 30 days4,771Last commit
7 hours agoLicense
AGPL-3.0
Collaborative markdown documents with real-time CRDT editing, AI agent cursors, mention linking, and built-in properties tied to your tasks, channels, and email.
Open Source Alternative to:
A self-building CRM powered by your email
Stars
Stars growing over the last 30 days4,771Last commit
7 hours agoLicense
AGPL-3.0
Automatically creates and enriches contacts, companies, and deal threads from your team's email. No data entry, no imports, no admin overhead.
Open Source Alternative to:
Team chat with email, tasks, and docs in one workspace
Stars
Stars growing over the last 30 days4,771Last commit
7 hours agoLicense
AGPL-3.0
Team chat app with inline threads, mention-based sharing, a unified inbox for chat and email, and an AI agent that works across your full workspace.
Open Source Alternative to:
Private AI chat with zero-access encryption
Stars
5,642Last commit
9 hours agoLicense
GPL-3.0
AI chat assistant from Proton that stores conversations with zero-access encryption, never logs chats, and never uses your data to train models.
Open Source Alternative to:
Managed compliance for SOC 2, ISO 27001, HIPAA, and more
Stars
Stars growing over the last 30 days1,467Last commit
5 hours agoLicense
MIT
Compliance management platform where dedicated compliance officers handle your entire program, from risk assessments to audit coordination, with automated evidence collection.
Open Source Alternative to:
AWS-compatible cloud APIs on infrastructure you control
Stars
Stars growing quickly over the last 30 days389Last commit
11 hours agoLicense
AGPL-3.0
Spinifex recreates EC2, S3, EBS, VPC, IAM, and more on your own hardware, so AWS-built software runs unchanged without touching a hyperscaler.
Open Source Alternative to:
An AI assistant that acts, not just answers
Stars
392,917Last commit
5 hours agoLicense
MIT
A personal AI assistant that connects to your existing chat apps and handles real tasks like email, calendar, and flight check-ins on your behalf.
Open Source Alternative to:
Desktop AI agent with persistent memory across platforms
Stars
Stars growing over the last 30 days255,365Last commit
5 hours agoLicense
MIT
Cross-platform desktop agent from Nous Research that connects to Telegram, Discord, Slack, WhatsApp, and more, with persistent memory, scheduling, and isolated sandboxing.
Open Source Alternative to:
AI coding agent for terminal, IDE, and desktop
Stars
Stars growing over the last 30 days218,185Last commit
5 hours agoLicense
MIT
Open source AI coding agent that works in your terminal, IDE, or desktop app, supporting 75+ LLM providers with no code storage.
Open Source Alternative to:
Visual workflow automation with code flexibility and AI agents
Stars
208,095Last commit
5 hours agoLicense
Unknown
Build automated workflows connecting 500+ apps, write custom code, and deploy AI agents with full visibility into every decision. Self-hostable or cloud.
Open Source Alternative to:
Build and run AI agents that handle recurring work for you
Stars
187,668Last commit
5 hours agoLicense
Other
Platform for building, deploying, and running AI agents that automate repeatable digital work across research, outreach, content, and support without writing code.
Open Source Alternative to:
Run open-source LLMs locally on your own machine
Stars
183,909Last commit
11 hours agoLicense
MIT
Runs open-source language models locally with a simple setup, plus optional cloud access for larger models when local hardware isn't enough.
Open Source Alternative to:
Build and deploy AI agents and RAG pipelines visually
Stars
158,982Last commit
5 hours agoLicense
Unknown
Visual platform for building agentic workflows, RAG pipelines, and LLM-powered apps. Supports hundreds of models, MCP integration, and self-hosted deployment.
Open Source Alternative to:
One interface for every AI model you run or connect
Stars
156,230Last commit
23 hours agoLicense
BSD-3-Clause
Self-hosted AI platform that connects local and cloud models, extends with Python, and keeps your data under your control.
Open Source Alternative to:
AI coding agent that works inside your terminal
Stars
130,006Last commit
5 hours agoLicense
Apache-2.0
Terminal-based AI coding agent that inspects files, edits code, runs commands, and integrates into CI pipelines using OpenAI's Codex models.
Open Source Alternative to:
Visual builder for AI agents and RAG pipelines
Stars
155,859Last commit
5 hours agoLicense
MIT
Build, deploy, and iterate on AI agents, RAG applications, and MCP servers using a drag-and-drop visual interface backed by Python.
Open Source Alternative to:
Run LLMs locally with minimal setup, maximum hardware support
Stars
131,767Last commit
5 hours agoLicense
MIT
C/C++ inference engine for large language models, supporting quantization, multi-GPU, Apple Silicon, and an OpenAI-compatible server across a wide range of hardware.
Open Source Alternative to:
Org chart, budgets, and governance for AI agent teams
Stars
Stars growing quickly over the last 30 days104,919Last commit
6 hours agoLicense
MIT
Manages teams of AI agents across business functions with org charts, goal alignment, cost tracking, ticket tracing, and board-level governance controls.
Open Source Alternative to:
Minimal terminal coding agent you can fully customize
Stars
Stars growing over the last 30 days116,538Last commit
5 hours agoLicense
MIT
Terminal-based coding agent with a minimal core, 15+ LLM providers, tree-structured session history, and a TypeScript extension system for building your own workflows.
Open Source Alternative to:
Collaborative whiteboard with a hand-drawn aesthetic
Stars
134,226Last commit
5 hours agoLicense
MIT
Virtual whiteboard for sketching diagrams, flowcharts, and wireframes with a distinctive hand-drawn look. Real-time collaboration built in.
Open Source Alternative to:
Self-hosted remote desktop you fully control
Stars
126,391Last commit
4 days agoLicense
AGPL-3.0
Cross-platform remote desktop software that runs on your own servers, giving you full data control as a direct alternative to TeamViewer and AnyDesk.
Open Source Alternative to:
Run multiple AI coding agents in parallel, side by side
Stars
Stars growing quickly over the last 30 days98,751Last commit
5 hours agoLicense
MIT
Agent Development Environment that runs Claude Code, Codex, Gemini, and other CLI agents in parallel across isolated git worktrees, with terminals, browser, diff review, and git tools built in.
Open Source Alternative to:
Self-hosted photo and video backup for your own server
Stars
116,704Last commit
5 hours agoLicense
AGPL-3.0
Back up, organize, search, and browse your personal photo and video library on your own server, with no third-party cloud access.
Open Source Alternative to:
High-throughput, memory-efficient serving engine for LLMs
Stars
94,189Last commit
5 hours agoLicense
Apache-2.0
Inference and serving engine for large language models, built for speed and hardware efficiency with an OpenAI-compatible API and support for a wide range of open models.
Open Source Alternative to:
Open source video editor that runs in your browser
Stars
Stars growing over the last 30 days95,419Last commit
26 days agoLicense
MIT
Browser-based, open source video editor built for privacy. No installs, no account required, works on any platform.
Open Source Alternative to:
Postgres-powered backend platform for production apps
Stars
111,992Last commit
5 hours agoLicense
Apache-2.0
Provides a full backend stack built on Postgres: authentication, auto-generated APIs, edge functions, realtime subscriptions, file storage, and vector search.
Open Source Alternative to:
Autonomous coding agents that complete real engineering tasks
Stars
Stars growing over the last 30 days91,338Last commit
5 hours agoLicense
MIT
AI agent platform that runs autonomous coding agents to plan, write, and ship changes across codebases end-to-end, with support for any model and self-hosted deployment.
Open Source Alternative to:
LLM-ready web crawler built for AI data pipelines
Stars
85,891Last commit
10 hours agoLicense
Apache-2.0
Open-source web crawler and scraper that produces clean, structured output optimized for LLMs, RAG pipelines, and AI agents. Supports async crawling, CSS/XPath/LLM extraction, and stealth browser control.
Open Source Alternative to:
Manage, build, and run AI agent teams around the clock
Stars
83,352Last commit
5 hours agoLicense
Unknown
A collaborative platform to create, schedule, and operate AI agents that handle long-running tasks, team workflows, and automated jobs without constant oversight.
Open Source Alternative to:
High-performance code editor built for speed and AI
Stars
91,944Last commit
7 hours agoLicense
GPL-3.0
A Rust-built code editor from the creators of Atom and Tree-sitter, combining native performance with multiplayer collaboration and deep AI integration.
Open Source Alternative to:
Hyperextensible, Lua-powered Vim-based text editor
Stars
103,075Last commit
8 hours agoLicense
Unknown
A modernized Vim fork with built-in LSP, Lua scripting, Tree-sitter parsing, and an async plugin architecture that works the same across every platform.
Open Source Alternative to:
Stellar Hosted – Managed Open Source software hosting in the EU: secure, compliant, fast.
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