Free
Stirling PDF
Open SourcePDF Tools · PDF & Documents
Self-hosted PDF toolbox with 50+ operations, locally run.
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PDF Tools · PDF & Documents
Self-hosted PDF toolbox with 50+ operations, locally run.
API Documentation · API Tools
Design-first API platform for specs, docs, mocking and governance.
Illustrations & Assets · Design & Prototyping
Freepik's library of customizable vector illustrations — recolor, animate and export for products and decks.
Payments · API Tools
The standard payments platform with excellent developer APIs.
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.
Ecosystem · CSS Tools
The Tailwind team's paid component library — polished UI kits, templates and React/Vue code for every block.
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.
Web3 Libraries · Web3 & Blockchain
Full web3 development kit — SDKs, contract deployment, wallets and built-in infrastructure for shipping dApps fast.
Relational · Database
PostgreSQL extension and cloud for time-series and analytics.
Compression & Optimization · Image & Media
Smart lossy compression for PNG and JPEG images.
Cheatsheets · Documentation & Learning
Community-maintained, practical examples for every CLI command.
Whiteboards & Diagrams · Design & Prototyping
Beautiful open-source infinite canvas SDK and whiteboard.
Models & LLM APIs · AI for Developers
Cloud for open-source model inference, fine-tuning and hosting.
Other Formats · Data Formats
Official TOML language site with spec, docs and editor support.
JSON · Data Formats
Convert JSON into TypeScript, Zod, GraphQL, Kotlin, Go structs and more.
Penetration Testing · Security
Guided, browser-based cybersecurity training with hands-on labs from beginner to offensive paths.
Serverless & BaaS · Database
Distributed SQLite-based database for edge and local-first apps.
Typography & Fonts · Design & Prototyping
Visual type-scale calculator — pick a ratio and base size, preview the resulting hierarchy live.
Search Engines · Database
Open-source, in-memory search engine focused on developer experience.
Typography & Fonts · Design & Prototyping
Curated font recommendations and pairing guides with real-website examples for every family.