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.
Modern kanban that's fast, fun, and refreshingly simple
Stars
8,257Last commit
8 hours agoLicense
Unknown
Track issues, ideas, and projects with a modern kanban board that's fast and straightforward. Free for 1000 cards, then $20/month for unlimited use.
Open Source Alternative to:
Cloud browser sessions for AI agents and web automation
Stars
7,845Last commit
13 hours agoLicense
Apache-2.0
Open-source browser infrastructure that lets AI agents and automation scripts control cloud browser fleets via a simple API, with built-in CAPTCHA solving and proxy management.
Open Source Alternative to:
Privacy-first CAPTCHA alternative with proof-of-work
Stars
Stars growing over the last 30 days8,105Last commit
8 days agoLicense
Apache-2.0
Lightweight open-source CAPTCHA solution using SHA-256 proof-of-work. 250x smaller than hCaptcha, fully customizable, and privacy-focused with zero telemetry.
Open Source Alternative to:
Flexible, scalable Node.js CMS and app framework
Stars
9,981Last commit
9 hours agoLicense
MIT
A powerful, customizable content management system and application framework built on Node.js, GraphQL, and React
Open Source Alternative to:
Distributed task queue for background jobs and workflows
Stars
8,148Last commit
8 hours agoLicense
MIT
Durable orchestration platform for managing AI agents, scheduling background tasks, and running mission-critical workflows.
Open Source Alternative to:
Magical data pipeline tool for seamless transformations
Stars
8,834Last commit
4 days agoLicense
Apache-2.0
Open-source data pipeline platform for effortless data integration, transformation, and orchestration using Python, SQL, and R.
Open Source Alternative to:
Self-hosted enterprise agent platform with real permissions
Stars
Stars growing quickly over the last 30 days6,695Last commit
16 hours agoLicense
MIT
Deploy AI agents inside your own infrastructure with document-grounded answers, computer use, and support for any AG-UI-compatible agent framework.
Open Source Alternative to:
Serverless backend platform for modern app development
Stars
9,363Last commit
8 hours agoLicense
MIT
Fully managed backend infrastructure with built-in authentication, database, storage, and serverless functions for rapid application development.
Open Source Alternative to:
Flexible e-commerce for modern businesses
Stars
8,527Last commit
20 hours agoLicense
MIT
A headless, API-first e-commerce framework built on Node.js with TypeScript, offering customization and scalability for online stores.
Open Source Alternative to:
Real-time observability for modern web applications
Stars
9,383Last commit
19 days agoLicense
Apache-2.0
Comprehensive monitoring solution offering error tracking, session replay, and performance insights for seamless debugging and optimization.
Open Source Alternative to:
Visual development platform for modern web experiences
Stars
8,868Last commit
5 days agoLicense
MIT
Drag-and-drop interface for creating and optimizing digital experiences, with headless CMS and powerful integrations.
Open Source Alternative to:
Open-source A/B testing and feature flagging platform
Stars
8,513Last commit
8 hours agoLicense
MIT
Powerful, developer-friendly experimentation tool for data-driven product decisions. Seamless integration, real-time insights, and flexible deployment.
Open Source Alternative to:
Fast, flexible VPN replacement with zero-trust security
Stars
9,121Last commit
9 hours agoLicense
Apache-2.0
Replace your VPN with zero-trust access built on WireGuard. Fast, scalable network security with simple policies and identity provider integration.
Open Source Alternative to:
Comprehensive open-source business management platform
Stars
Stars growing over the last 30 days8,405Last commit
12 hours agoLicense
AGPL-3.0
All-in-one solution for ERP, CRM, HRM, ATS, and project management to streamline your business operations
Open Source Alternative to:
Security-first diagramming with no login required
Stars
Stars growing over the last 30 days8,885Last commit
2 days agoLicense
Apache-2.0
Create professional diagrams online or offline with security-first approach. No registration needed. Works with Google Drive, SharePoint, Atlassian, and more.
Open Source Alternative to:
Self-hostable voice agent platform with full model control
Stars
Stars growing over the last 30 days5,909Last commit
11 hours agoLicense
BSD-2-Clause
Open-source voice agent platform that lets you plug in your own STT, LLM, and TTS models, deploy on-prem or in your VPC, and build agents via MCP or a visual workflow builder.
Open Source Alternative to:
Build and play games inside a game engine that runs live
Stars
6,497Last commit
17 hours agoLicense
MIT
A game creation platform built on Valve's Source 2 engine, letting you build, share, and play games without leaving the environment.
Open Source Alternative to:
Simple yet powerful CI/CD engine with great extensibility
Stars
8,022Last commit
19 hours agoLicense
Apache-2.0
Open-source CI/CD platform using Docker containers for pipeline execution. Create multiple workflows, extend with plugins, and enjoy free lifetime access.
Open Source Alternative to:
Full-stack observability without code changes
Stars
7,977Last commit
19 hours agoLicense
Apache-2.0
Coroot simplifies system monitoring by providing metrics, logs, traces, and profiling with zero instrumentation, leveraging eBPF technology.
Open Source Alternative to:
Comprehensive monitoring and incident management platform
Stars
7,750Last commit
8 hours agoLicense
Apache-2.0
All-in-one solution for uptime monitoring, incident management, and status pages to keep your services running smoothly
Open Source Alternative to:
Secure, customizable e-signatures for modern businesses
Stars
7,124Last commit
1 day agoLicense
AGPL-3.0
A powerful, open-source e-signature solution offering customization, integration, and enhanced security for businesses of all sizes.
Open Source Alternative to:
A team of AI agents in a chat app, on your own machine
Stars
Stars growing quickly over the last 30 days5,231Last commit
8 hours agoLicense
Apache-2.0
Run a team of AI agents locally on your own API keys and subscriptions, with scheduled tasks, computer use, and Gmail, GitHub and Slack integrations.
Open Source Alternative to:
Simplify expense management for businesses of all sizes
Stars
5,065Last commit
8 hours agoLicense
MIT
Automate expense reporting, reimbursements, and corporate card management with real-time data sync and powerful integrations.
Modular auth, payments, emails, and analytics for your product
Stars
6,875Last commit
17 hours agoLicense
Unknown
Self-hostable platform combining user auth, payments, email, and analytics into modular building blocks that fit around your existing product.
Open Source Alternative to:
Visual app builder that integrates with your existing codebase
Stars
7,120Last commit
10 hours agoLicense
MIT
Open-source visual editor for building websites and web apps. Connect to any data source, design custom UIs, and ship production React code without leaving your stack.
Open Source Alternative to:
Dashboard for running multiple coding agents in parallel
Stars
Stars growing over the last 30 days6,031Last commit
13 hours agoLicense
Apache-2.0
Desktop app that runs 25+ coding agents simultaneously, each isolated in its own Git worktree, so you can orchestrate code changes without switching tools.
Open Source Alternative to:
The tensor database for AI data
Stars
9,254Last commit
5 months agoLicense
Apache-2.0
Deep Lake is an open-source database for storing, querying and managing complex AI data like images, audio, and embeddings.
Open Source Alternative to:
Open-source serverless CMS for modern web projects
Stars
8,048Last commit
9 hours agoLicense
MIT
A powerful, scalable platform for building custom websites and apps with serverless architecture, offering flexibility and cost-efficiency.
Open Source Alternative to:
Open-source cloud communications platform for developers
Stars
8,142Last commit
11 hours agoLicense
MIT
Build and deploy powerful voice and messaging applications with ease using Fonoster's flexible, scalable, and developer-friendly platform.
Open Source Alternative to:
Self-hosted AI agents that do real work on your machine
Stars
Stars growing quickly over the last 30 days4,828Last commit
9 hours agoLicense
Apache-2.0
Run persistent AI bots that sign into your tools, complete tasks autonomously, and ask for approval when needed. Your keys, your model, your infrastructure.
Open Source Alternative to:
Auto-generated network diagrams that stay current
Stars
5,888Last commit
1 day agoLicense
AGPL-3.0
Discovers your network via SNMP, LLDP, and ARP, then builds and maintains L2/L3 topology diagrams, host inventories, and service dependency maps automatically.
Open Source Alternative to:
Self-hosted file sharing built for digital sovereignty
Stars
6,193Last commit
9 hours agoLicense
Apache-2.0
Self-hostable cloud file management and collaboration platform with an integrated office suite, zero-trust security, and GDPR compliance for teams and organizations.
Open Source Alternative to:
Desktop SQL client with built-in MCP for AI agent access
Stars
Stars growing over the last 30 days5,241Last commit
1 day agoLicense
Apache-2.0
Desktop database client for PostgreSQL, MySQL/MariaDB, SQLite, and 14+ more databases, with a built-in MCP server, SQL notebooks, visual query builder, and a plugin system.
Open Source Alternative to:
Secure collaboration with end-to-end encryption
Stars
8,019Last commit
1 day agoLicense
AGPL-3.0
Open-source collaboration suite offering encrypted document editing, file sharing, and team workspaces with complete privacy protection.
Open Source Alternative to:
Open-source legal AI that law firms control and extend
Stars
4,363Last commit
16 hours agoLicense
AGPL-3.0
Self-hostable alternative to Harvey and Legora with document analysis, contract drafting, tabular review, and reusable workflows. Zero licensing costs, full data control.
Open Source Alternative to:
Build reliable AI apps with comprehensive observability
Stars
6,227Last commit
10 hours agoLicense
Apache-2.0
Open-source platform for logging, monitoring, and debugging LLM applications. Route, debug, and analyze AI apps with comprehensive observability tools.
Open Source Alternative to:
Build stateful backends with in-memory actors
Stars
6,318Last commit
9 hours agoLicense
Apache-2.0
Open-source infrastructure for long-lived, in-memory processes called Actors. Combines state and compute with sub-millisecond latency, realtime capabilities, and horizontal scaling.
Open Source Alternative to:
Launch Your Store in Minutes, No Code Needed
Stars
5,526Last commit
1 day agoLicense
MIT
Fast, modern e-commerce with instant setup and full customization. Powered by Stripe for seamless transactions.
Open Source Alternative to:
Transform SQL into beautiful data stories
Stars
7,037Last commit
4 days agoLicense
MIT
Create data-driven websites and reports using SQL and Markdown, with automatic visualizations and interactive elements.
Open Source Alternative to:
Ad-free photo sharing with privacy and federation
Stars
7,124Last commit
9 hours agoLicense
AGPL-3.0
Decentralized photo sharing platform with chronological feeds, privacy controls, and ActivityPub federation. No ads, no algorithms, just authentic connections.
Open Source Alternative to:
Flexible project management you can host yourself
Stars
6,050Last commit
12 hours agoLicense
GPL-2.0
Self-hosted project management web app built on Ruby on Rails with issue tracking, time logging, SCM integration, and multi-project support across any database.
Open Source Alternative to:
Open source kanban boards with unlimited everything
Stars
5,786Last commit
1 day agoLicense
AGPL-3.0
Free kanban project management with unlimited boards, lists, and cards. Import Trello boards, collaborate with teams, and self-host for complete control.
Open Source Alternative to:
Postiz – The All-in-One agentic social media scheduling tool
Postiz
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