Free
System Design Primer
Open SourceReferences · Documentation & Learning
The most-starred system design study guide — scalable architectures, trade-offs and exercises, free and open source.
system-designarchitectureinterviewlearning
Browse the complete directory — use filters to narrow down.
References · Documentation & Learning
The most-starred system design study guide — scalable architectures, trade-offs and exercises, free and open source.
Practice & Challenges · Documentation & Learning
Free, curated interview prep: algorithms study plans, behavioral questions and resume advice by ex-Facebook engineers.
Courses & Tutorials · Documentation & Learning
Free, open-source full-stack web development curriculum.
Relational · Database
PostgreSQL extension and cloud for time-series and analytics.
Cheatsheets · Documentation & Learning
Community-maintained, practical examples for every CLI command.
Whiteboards & Diagrams · Design & Prototyping
Beautiful open-source infinite canvas SDK and whiteboard.
JSON · Data Formats
Convert JSON into TypeScript, Zod, GraphQL, Kotlin, Go structs and more.
Serverless & BaaS · Database
Distributed SQLite-based database for edge and local-first apps.
Search Engines · Database
Open-source, in-memory search engine focused on developer experience.
Web Analytics · Monitoring & Observability
Simple, self-hostable web analytics you own (trending).
Feature Flags · DevOps
Open-source feature flag platform you can self-host — strategies, gradual rollouts and an activation dashboard.
NoSQL · Database
Community-driven Redis fork under the Linux Foundation (trending).
Vector Databases · AI for Developers
Open-source vector database with hybrid search and modules.
API Mocking · API Tools
Instantly inspect and test incoming webhooks with a temporary URL.
API Mocking · API Tools
Flexible API mocking and service virtualization for HTTP.
YAML · Data Formats
Validate and beautify YAML online.