Free
Headers & CSP · Security
Scan any site's HTTP security response headers and get a grade.
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Headers & CSP · Security
Scan any site's HTTP security response headers and get a grade.
Cheatsheets & Learning · Git & Version Control
The SemVer specification for meaningful version numbers.
Dependency Security · Security
Fast static analysis for finding bugs and vulnerabilities in code.
Hosting & Collaboration · Git & Version Control
The badge service for READMEs — build status, version, downloads and custom badges as compact SVGs.
Design Systems · Design & Prototyping
Shopify's design system with components, tokens and guidance.
APM & Tracing · Monitoring & Observability
Open-source Datadog alternative built on OpenTelemetry.
SQL Tools
Classic online tool for testing and sharing SQL queries.
SQL Tools
Popular open-source JavaScript library to format SQL in your apps.
SQL Tools
Interactive lessons for learning SQL basics quickly.
SQL Tools
Free online SQL formatter and beautifier with many dialect options.
Relational · Database
Self-contained, serverless, embedded SQL database engine.
SQL Tools
Interactive SQL tutorial with quizzes for beginners.
Compression & Optimization · Image & Media
Google's browser image compressor with advanced codecs (WebP, AVIF).
SSL & TLS · Security
Deep SSL/TLS server certificate and configuration analysis.
Communities · Documentation & Learning
The largest Q&A community for programmers.
Markdown · PDF & Documents
Browser Markdown editor with Google Drive and GitHub sync.
PDF Tools · PDF & Documents
Self-hosted PDF toolbox with 50+ operations, locally run.
Illustrations & Assets · Design & Prototyping
Freepik's library of customizable vector illustrations — recolor, animate and export for products and decks.
NoSQL · Database
Multi-model database with records, graphs and documents (trending).
Compression & Optimization · Image & Media
Browser GUI for SVGO, optimizing SVG files with previews.
API Documentation · API Tools
OpenAPI tooling suite by SmartBear: UI, editor, codegen and more.
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.