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.
Website analytics, uptime monitoring, and server status in one
Stars
3,115Last commit
2 days agoLicense
Apache-2.0
Self-hostable platform combining website analytics, uptime monitoring, server status, Docker tracking, status pages, and telemetry for indie developers and small teams.
Open Source Alternative to:
Fast and beautiful launcher for quick access to apps and tools
Stars
3,174Last commit
6 days agoLicense
MIT
A modern macOS launcher that provides instant access to applications, utilities, and system functions through an elegant and efficient interface.
Open Source Alternative to:
Modern open-source billing platform for hosting businesses
Stars
Stars growing quickly over the last 30 days2,766Last commit
1 day agoLicense
MIT
Automate subscriptions and manage payments with a flexible, open-source billing system designed specifically for hosting providers.
Open Source Alternative to:
Visual website builder for effortless web design
Stars
2,446Last commit
14 hours agoLicense
MIT
Frappe Builder is an open-source, low-code website builder that enables users to create beautiful, responsive websites with an intuitive visual interface.
Open Source Alternative to:
Next-Gen CAPTCHA and Spam Protection, GDPR compliant
Stars
2,834Last commit
2 days agoLicense
MIT
ALTCHA offers cutting-edge spam and abuse protection for websites and apps, with privacy-friendly CAPTCHA alternatives designed for GDPR compliance.
Open Source Alternative to:
Open-source customer communication platform
Stars
3,574Last commit
4 months agoLicense
Unknown
Versatile messaging solution for businesses to engage customers through multiple channels, with AI-powered automation and analytics.
Open Source Alternative to:
Self-hosted home automation without the cloud
Stars
3,247Last commit
10 hours agoLicense
Apache-2.0
Privacy-first home automation platform that runs locally on your hardware, supports Zigbee, Matter, and MQTT, and lets you automate your home without coding.
Open Source Alternative to:
Route GenAI traffic with confidence using open source
Stars
Stars growing over the last 30 days2,247Last commit
24 hours agoLicense
Apache-2.0
Open source gateway built on Envoy for routing application traffic to GenAI services. Supports 16+ LLM providers including OpenAI, Anthropic, AWS Bedrock.
Open Source Alternative to:
Code with Claude, Codex, Gemini, and more in one workspace
Stars
Stars growing quickly over the last 30 days2,126Last commit
1 day agoLicense
MIT
Desktop coding workspace that connects to AI subscriptions you already have, with parallel agents, worktrees, one-click PRs, and multi-project management.
Open Source Alternative to:
Create, sell, and manage online courses with full control
Stars
Stars growing over the last 30 days2,404Last commit
3 days agoLicense
AGPL-3.0
Open-source LMS for building and selling courses with a block-based editor, built-in payments, AI tools, analytics, and white-labeling. Self-host or use the cloud.
Open Source Alternative to:
Modern desktop accounting made simple and free
Stars
4,999Last commit
18 days agoLicense
AGPL-3.0
A user-friendly desktop accounting software that helps businesses manage invoices, track expenses, and handle bookkeeping with a modern interface.
Open Source Alternative to:
Get audit-ready for SOC 2, ISO 27001, HIPAA, and GDPR
Stars
Stars growing over the last 30 days2,047Last commit
11 days agoLicense
AGPL-3.0
AI-driven compliance platform that automates evidence collection, policy generation, and continuous monitoring across 580+ integrations for SOC 2, ISO 27001, HIPAA, and GDPR.
Open Source Alternative to:
Create engaging product tours and user onboarding experiences
Stars
2,325Last commit
11 hours agoLicense
AGPL-3.0
Open-source platform for building interactive product tours, tooltips, and in-app guides to improve user engagement and feature adoption without complex coding
Open Source Alternative to:
Self-hosted email platform with visual editor & analytics
Stars
2,251Last commit
11 hours agoLicense
AGPL-3.0
Free open-source email platform for newsletters and transactional emails. Self-hosted alternative to Mailchimp with visual MJML editor, A/B testing, and analytics.
Open Source Alternative to:
Free DNS management and URL shortening platform
Stars
2,288Last commit
3 days agoLicense
MIT
WR.DO offers free domain name distribution and short URL generation, built on Cloudflare's infrastructure for reliability and speed.
Open Source Alternative to:
Complete IT infrastructure monitoring made simple
Stars
Stars growing over the last 30 days2,603Last commit
11 hours agoLicense
GPL-2.0
Monitor your entire IT infrastructure with 2,000+ plugins, automated discovery, and scalable architecture. Open source and enterprise solutions available.
Open Source Alternative to:
Open canvas for designing and building web apps
Stars
2,687Last commit
1 day agoLicense
Apache-2.0
Design and build web applications on an open canvas with AI-powered tools, Figma integration, pixel drawing, and a modular SDK built for extensibility.
Open Source Alternative to:
Create beautiful images of your code
Stars
2,363Last commit
5 days agoLicense
MIT
Turn your code into beautiful images. Choose from a range of syntax colors, hide or show the background, and toggle between a dark and light window.
Build privacy-compliant cookie banners with full control
Stars
Stars growing over the last 30 days1,989Last commit
14 hours agoLicense
Apache-2.0
Open source consent management framework for modern web apps. Framework-agnostic, fully customizable, and performance-first with no vendor lock-in.
Open Source Alternative to:
Design, prototype, and test user experiences with ease
Stars
2,741Last commit
9 days agoLicense
GPL-3.0
Quant-UX is an open-source tool for creating interactive prototypes, conducting user tests, and analyzing results to improve UX design.
Open Source Alternative to:
AI agents that transform merchant risk decisions at scale
Stars
2,448Last commit
12 days agoLicense
Unknown
Reduce fraud, accelerate underwriting, and maintain compliance with AI-driven merchant risk intelligence for PSPs, banks, and fintechs.
Open Source Alternative to:
Sell tickets for events, conferences, and exhibitions
Stars
2,542Last commit
11 hours agoLicense
Unknown
Full-stack ticketing platform covering online shop, point of sale, access control, and hardware for events of any size or industry.
Open Source Alternative to:
Secure password manager with end-to-end encryption
Stars
2,930Last commit
11 hours agoLicense
AGPL-3.0
Open-source password manager with end-to-end encryption for passwords, credit cards, notes, and documents. Cross-platform sync with secure sharing capabilities.
Open Source Alternative to:
AI-native CRM/ERP foundation with 80% already built
Stars
Stars growing over the last 30 days1,870Last commit
11 hours agoLicense
MIT
A modular CRM/ERP framework built on Next.js and TypeScript that encodes hundreds of architectural decisions so dev teams can ship production features in days, not months.
Open Source Alternative to:
Comprehensive open-source HR management solution
Stars
1,462Last commit
23 hours agoLicense
LGPL-2.1
Horilla is a free, open-source HRMS that streamlines HR processes, from recruitment to offboarding, with customizable modules.
Open Source Alternative to:
OpenTelemetry observability with traces, logs, and metrics
Stars
Stars growing over the last 30 days1,848Last commit
10 hours agoLicense
Unknown
Observability platform built on OpenTelemetry and ClickHouse. Collect, visualize, and query distributed traces, logs, and metrics, with an MCP server for AI agent diagnostics.
Open Source Alternative to:
Powerful, customizable web analytics for your site
Stars
2,695Last commit
11 hours agoLicense
GPL-2.0
Open-source web analytics platform offering comprehensive visitor tracking, customizable dashboards, and data ownership for websites and applications.
Open Source Alternative to:
GPU orchestration across clouds, Kubernetes, and on-prem
Stars
2,284Last commit
10 hours agoLicense
MPL-2.0
Unified control plane for AI compute that provisions and schedules GPU workloads across any cloud, Kubernetes cluster, or bare-metal server.
Open Source Alternative to:
Self-hosted error tracking for full control and scalability
Stars
2,135Last commit
1 day agoLicense
Unknown
Bugsink offers real-time error tracking with self-hosting capabilities, allowing easy installation and connection to any app using Sentry-compatible SDKs.
Open Source Alternative to:
Build your custom learning academy in minutes
Stars
1,725Last commit
18 hours agoLicense
AGPL-3.0
Open source LMS designed for companies and training organizations. Create, manage, and deliver courses with AI support, customizable dashboards, and collaborative features.
Open Source Alternative to:
Build APIs like code with Git-native workspace
Stars
Stars growing over the last 30 days1,869Last commit
1 day agoLicense
Apache-2.0
Offline-first API workspace that unifies specs, docs, tests, and mocks in programmable Markdown blocks. Version control everything in plain text files.
Open Source Alternative to:
Unified API development ecosystem for modern teams
Stars
2,618Last commit
8 months agoLicense
AGPL-3.0
All-in-one platform for API testing, documentation, and collaboration, simplifying the entire API development lifecycle.
Open Source Alternative to:
Simplify your workflow with offline Kanban boards
Stars
2,067Last commit
3 days agoLicense
GPL-3.0
Kanri is a free, open-source personal Kanban app that works offline, offering a modern and simple experience while respecting your privacy.
Open Source Alternative to:
Local meeting recorder that keeps your audio off the cloud
Stars
Stars growing over the last 30 days1,560Last commit
13 hours agoLicense
MIT
Records meetings and voice memos locally using whisper.cpp, writes structured markdown to disk, and exposes 31 MCP tools so any AI agent can query your conversation history.
Open Source Alternative to:
Self-hosted CRM with built-in AI chat and agent tools
Stars
Stars growing over the last 30 days1,773Last commit
20 hours agoLicense
AGPL-3.0
Open-source CRM with a built-in AI assistant, 37 MCP tools for external agents, custom fields, role-based permissions, and a REST API. No per-seat pricing.
Open Source Alternative to:
Open-source email marketing for the privacy-conscious
Stars
2,238Last commit
18 days agoLicense
AGPL-3.0
Self-hosted newsletter platform with powerful features, data protection, and full control over your mailing lists and campaigns.
Open Source Alternative to:
Full-text search API with real-time indexing and crawling
Stars
1,916Last commit
22 hours agoLicense
Apache-2.0
Cloud search API and crawler service supporting billions of documents, real-time indexing, autocomplete, faceted filtering, and multi-language text across any application.
Open Source Alternative to:
Create custom spaces to chat, game, and connect globally
Stars
Stars growing quickly over the last 30 days2,008Last commit
11 hours agoLicense
MIT
Build your own community space for gaming, chatting, and hanging out with friends worldwide. Customize your environment for the perfect social experience.
Open Source Alternative to:
Unified API for all LLM providers with analytics
Stars
1,694Last commit
24 hours agoLicense
MIT
Route, manage, and analyze LLM requests across multiple providers with one API. Compatible with OpenAI format, includes usage analytics and performance monitoring.
Open Source Alternative to:
Automated localization for modern development teams
Stars
2,033Last commit
5 months agoLicense
MIT
A developer-focused localization platform that automates translation workflows within your existing development pipeline and CI/CD processes.
Open Source Alternative to:
Collaborative content creation for technical teams
Stars
2,005Last commit
9 days agoLicense
AGPL-3.0
A powerful platform for technical writing, offering real-time collaboration, version control, and seamless integrations.
Open Source Alternative to:
Enterprise file sync, share, and collaboration platform
Stars
2,155Last commit
11 hours agoLicense
Apache-2.0
Self-hostable file platform for enterprises needing data sovereignty, real-time document collaboration, and compliance with GDPR, HIPAA, and other regulations.
Open Source Alternative to:
Capture – Capture screenshots, generate PDFs, scrape content, extract metadata, and automate browsers with one API.
Stellar Hosted
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