Open Source Projects using OpenAPI
A curated collection of the 135 best open source software using OpenAPI. Find the most popular and trending open source projects to learn from, contribute to, or use in your own projects.
Visual app builder that integrates with your existing codebase
Stars
6,973Last commit
5 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:
Effortless API mocking for seamless development
Stars
8,379Last commit
4 hours agoLicense
MIT
Create, run, and share mock REST APIs without coding. Boost productivity with an intuitive interface and powerful features.
Open Source Alternative to:
Build reliable AI apps with comprehensive observability
Stars
6,102Last commit
19 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
6,087Last commit
11 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:
Virtual office platform for engaging remote collaboration
Stars
5,733Last commit
2 hours agoLicense
Unknown
Create customizable virtual workspaces for remote teams to interact naturally, host events, and collaborate through spontaneous conversations and scheduled meetings.
Open Source Alternative to:
Secure, scalable API key management for developers
Stars
5,423Last commit
1 hour agoLicense
AGPL-3.0
Streamline API authentication with UnKey's powerful, developer-friendly platform for creating, revoking, and monitoring API keys.
Open Source Alternative to:
Build scalable authorization in minutes, not months
Stars
5,940Last commit
10 hours agoLicense
AGPL-3.0
Open-source authorization service for implementing fine-grained access controls. Centralized, scalable solution supporting RBAC, ABAC and ReBAC with Google Zanzibar-inspired architecture.
Open Source Alternative to:
Continuous web-based localization for global reach
Stars
6,039Last commit
6 hours agoLicense
GPL-3.0
Web-based continuous localization platform with version control integration, quality checks, and clean interface. Used by 2,500+ projects in 165+ countries.
Open Source Alternative to:
Deploy a professional status page in minutes, no coding required
Stars
5,129Last commit
6 days agoLicense
MIT
Free, open-source status page and uptime monitor with Docker deployment. Track 11 service types, manage incidents, schedule maintenance, and notify subscribers instantly.
Open Source Alternative to:
Pay per email sent, not for contact storage
Stars
4,640Last commit
3 days agoLicense
AGPL-3.0
Open source email platform for transactional and marketing emails. Self-host or use cloud service with transparent pricing - pay only for emails sent.
Open Source Alternative to:
Build, automate, and improve AI agents with your team
Stars
4,544Last commit
43 minutes agoLicense
MIT
Open-source workspace for building and running AI agents: chat-driven development, scheduling, human-in-the-loop approvals, versioning, and tracing. Self-host or use the cloud.
Open Source Alternative to:
Free open-source appointment booking for any business
Stars
4,339Last commit
3 hours agoLicense
GPL-3.0
Self-hosted appointment scheduling solution with Google Calendar sync, customizable workflows, and no monthly fees. Perfect for healthcare, salons, and service businesses.
Open Source Alternative to:
Open source security automation platform for builders
Stars
3,780Last commit
43 minutes agoLicense
AGPL-3.0
Tracecat is a scalable, self-hostable platform for automating security workflows and playbooks without limits.
Open Source Alternative to:
Git-native feature management for developers
Stars
4,882Last commit
10 hours agoLicense
GPL-3.0
A feature flag platform that integrates with Git workflows, enabling developers to manage features directly in their codebase.
Open Source Alternative to:
Create powerful forms with ease and flexibility
Stars
3,643Last commit
22 hours agoLicense
AGPL-3.0
A versatile open-source form builder for collecting data, managing submissions, and integrating with your favorite tools.
Open Source Alternative to:
Feature-rich backend that runs anywhere you need it
Stars
3,751Last commit
5 months agoLicense
Apache-2.0
Lightweight Firebase alternative with database, auth, storage, and workflows. Framework-agnostic backend that integrates with NextJS, Remix, Hono and more.
Open Source Alternative to:
Stripe payments, usage tracking, and paywalls in 3 functions
Stars
2,649Last commit
1 hour agoLicense
Apache-2.0
Simplify Stripe integration for AI startups with 3 functions, 0 webhooks. Build pricing plans in 30 minutes with usage tracking, credits, and feature controls.
Open Source Alternative to:
Open-source customer engagement platform for automation
Stars
2,914Last commit
5 months agoLicense
MIT
Dittofeed offers low-code tools for message automation across multiple channels, including powerful segmentation and personalization features.
Open Source Alternative to:
Create engaging product tours and user onboarding experiences
Stars
2,290Last commit
6 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:
Open canvas for designing and building web apps
Stars
2,621Last commit
5 days 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:
Self-hosted email platform with visual editor & analytics
Stars
2,077Last commit
10 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:
Complete IT infrastructure monitoring made simple
Stars
2,349Last commit
43 minutes 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:
AI-native CRM/ERP foundation with 80% already built
Stars
1,682Last commit
2 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:
Real-time usage metering and billing for AI companies
Stars
2,231Last commit
4 hours agoLicense
Apache-2.0
Open source billing platform that turns events into revenue with real-time metering, usage limits, and flexible pricing. Integrates with Stripe, CRMs, and payment providers.
Open Source Alternative to:
OpenTelemetry observability with traces, logs, and metrics
Stars
1,727Last commit
2 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:
Local-first, offline-first no-code database platform
Stars
2,975Last commit
1 year agoLicense
AGPL-3.0
Build and manage custom databases with ease, create type-safe APIs, and develop applications quickly
Open Source Alternative to:
Full-text search API with real-time indexing and crawling
Stars
1,908Last commit
3 days 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:
Collaborative content creation for technical teams
Stars
1,993Last commit
5 days agoLicense
AGPL-3.0
A powerful platform for technical writing, offering real-time collaboration, version control, and seamless integrations.
Open Source Alternative to:
Unified API for all LLM providers with analytics
Stars
1,576Last commit
45 minutes 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:
Privacy-first proof-of-work CAPTCHA without user friction
Stars
2,486Last commit
11 months agoLicense
AGPL-3.0
Privacy-focused proof-of-work CAPTCHA system that silently protects websites without tracking users or requiring image solving. Drop-in replacement for reCAPTCHA.
Open Source Alternative to:
Cross-system automation and knowledge base for accounting firms
Stars
1,718Last commit
3 months agoLicense
Unknown
Connects client data across tools, automates recurring accounting workflows, and maintains a self-updating knowledge base with human approval controls.
AI code review that learns your team's standards
Stars
1,326Last commit
23 hours agoLicense
AGPL-3.0
Open source AI code reviewer that analyzes pull requests for quality, security, and performance while respecting your existing rules and model preferences.
Open Source Alternative to:
GitOps orchestration for infrastructure as code
Stars
1,268Last commit
6 hours agoLicense
MPL-2.0
Automate infrastructure changes with secure GitOps workflows. Plan, validate, and deploy Terraform, OpenTofu, and Pulumi directly from pull requests.
Open Source Alternative to:
Open-source webhooks for seamless integrations
Stars
1,481Last commit
2 hours agoLicense
SSPL-1.0
Self-hosted webhook solution for effortless event-driven communication between applications, enhancing system interoperability and automation.
Open Source Alternative to:
Self-hosted SERP API for Google, Bing, Yandex, and more
Stars
1,306Last commit
1 month agoLicense
MIT
Query Google, Bing, Yandex, Baidu, DuckDuckGo, and Ecosia through one REST API. Self-host free under MIT, or use the managed cloud option.
Open Source Alternative to:
Flexible billing infrastructure for modern SaaS
Stars
1,222Last commit
20 hours agoLicense
AGPL-3.0
Open-source pricing and billing platform that helps SaaS companies launch, test, and scale complex billing models with ease. Features metering, invoicing, and real-time data.
Open Source Alternative to:
Build AI agents and automate complex workflows seamlessly
Stars
993Last commit
12 hours agoLicense
Apache-2.0
Create intelligent automation workflows combining AI agents with your favorite apps and services. Connect, automate, and scale your operations without complex coding.
Open Source Alternative to:
One self-hosted binary replaces Vercel, Sentry, and analytics tools
Stars
686Last commit
43 minutes agoLicense
Apache-2.0
Self-hosted platform for small dev teams combining deployments, error tracking, analytics, session replay, uptime monitoring, and managed databases in one dashboard.
Open Source Alternative to:
Persistent cloud VMs that hibernate and wake in seconds
Stars
496Last commit
17 hours agoLicense
Apache-2.0
Provides always-on virtual machines for AI agents with full OS access, persistent state, elastic CPU/memory resizing, and instant checkpoints.
Open Source Alternative to:
Visual regression testing for seamless UI development
Stars
615Last commit
5 hours agoLicense
MIT
Automate visual testing, catch UI bugs early, and collaborate effortlessly with your team to maintain pixel-perfect interfaces.
Open Source Alternative to:
Web3 writing platform for content creators and crypto enthusiasts
Stars
490Last commit
4 days agoLicense
MIT
Sigle is a secure, open-source platform for Web3 writers to create, publish, and monetize content on the Bitcoin blockchain.
Open Source Alternative to:
Unified API, event, and AI agent management platform
Stars
444Last commit
1 hour agoLicense
Apache-2.0
Full-lifecycle API management platform that unifies synchronous and asynchronous ecosystems. Manage APIs, event streams, and AI agents with enterprise security and 4x faster gateway performance.
Open Source Alternative to:
Sent – A unified API for sending messages across SMS, RCS, and apps like WhatsApp.
Sent
Capture
Sent