Awesome Developer Tools

June 23, 2026 · View on GitHub

A curated list of in-browser bookmarklets, tools, and resources for modern full-stack software engineers.

Inspired by the awesome list thing.

Bookmarklets

  • artoo.js - Client-side scraping utility for the currently loaded uri.
  • DOM Monster - A cross-platform, cross-browser bookmarklet that will analyze the DOM & other features of the page you're on.
  • Make Bookmarklets - Online tool to turn JavaScript into a bookmarklet.
  • Related Repos - Quickly view alternative repositories while browsing on GitHub. Results are updated daily.
  • Rulers Guides - A JavaScript library which enables Photoshop-like rulers and guides interface on a web page.

Tools

API Clients

  • Hoppscotch - A lightweight, web-based API development suite.
  • Reqbin - REST & SOAP API Online Testing Tool

Copy/Paste Scripts & Styles

  • crontab guru - The quick and simple editor for cron schedule expressions by Cronitor
  • Devtools Tips - Copy-and-paste'able collection of useful cross-browser DevTools snippets.

CSS

Debug JavaScript

Diagramming & Scratch

  • asciiflow - ASCIIFlow is a client-side only web based application for drawing ASCII diagrams.
  • dbdiagram - Draw Entity-Relationship Diagrams, Painlessly.
  • dot-to-ascii - Graphviz to ASCII converter using Graph::Easy.
  • Excalidraw - Virtual whiteboard.
  • JSONCrack - Visualize CSV/JSON/TOML/XML/YAML instantly into graphs.
  • Markmap - Visualize markdown as a feature-rich mindmaps.
  • nomnoml - A tool for drawing UML diagrams based on a simple syntax.
  • Octopus - Lightning-fast visual sitemap builder & website planner.
  • Sequence Diagram - An online tool / software for creating UML sequence diagrams.

Diffing

  • ApiNotes - Compare two OpenAPI 3.x & Swagger 2.0 specifications side by side. Detect breaking changes, added/removed endpoints, and parameter diffs.
  • Diff Text - Quickly highlight differences in plain text, code, or JSON files.
  • JSONDiffPatch - Run a visual or non-visual diff on two JSON blobs.

File Sharing

  • file.io - Ephemeral file sharing. Convenient, anonymous and secure.
  • instant.io - Instant file transfer/sharing over WebTorrent
  • pairdrop - Instant file transfer over your local network (P2P)

Generators

  • ByteTools Passphrase Generator - Generate secure, memorable passphrases with customizable options. 100% client-side processing.
  • ByteTools QR Generator - Generate QR codes including WiFi QR codes. Works offline, no data sent to servers.
  • ColorForge - Generate color palettes with real-time preview, CSS/SCSS export, and shareable URLs.
  • CORS Header Generator - Generate CORS headers for your API with visual configuration. 100% client-side, no data sent to server.
  • CSS Filter Generator - Compose CSS filter effects (blur, brightness, contrast, grayscale) with real-time preview. Runs entirely in browser.
  • har2sdk - Paste a browser HAR file and generate a typed TypeScript fetch SDK with semantic method names, resource grouping, and auth detection.
  • JSONGenerator - Create random JSON data
  • MetaForge - Preview meta tags for Google, Facebook, and Twitter before publishing.
  • Mockium - Create test data
  • NGINXConfig - The easiest way to configure a performant, secure, and stable NGINX server.
  • PassForge - Generate secure passwords with customizable options and strength indicators.
  • Pictera - Generate beautiful Open Graph images with no design skills required.
  • Sovereign Gradient Forge - Create CSS gradients with a visual editor.
  • Sovereign Hash Forge - Generate SHA-256, MD5, and other hashes in the browser.
  • Sovereign Shadow Forge - Design CSS box-shadows with a visual builder.
  • Toolshref ZOD Schema Generator - Generate JSON to TypeScript Zod validation schemas instantly.
  • UUID Generator - Generate UUID v1, v4, v5, or v7 (RFC 9562) in browser. Bulk generation up to 1,000. Uses Web Crypto CSPRNG.

Image

Performance

Playgrounds

  • codepen - Social development environment for front-end designers and developers. Build and deploy a website, show off your work, build test cases to learn and debug, and find inspiration.
  • CodeSandbox - Online code editor and sandbox
  • Ellie - The Elm Live Editor
  • ES.nextBin - Like RequireBin but ES2015
  • ESM - A fast, smart, & global CDN for modern(es2015+) web development.
  • JSBin - JS/Coffee/Babel/Babel/Live/JSX/HTML/Markdown/Pug/CSS/Stylus/LESS/Sass
  • JSFiddle - JS/ES3/Coffee/HTML/CSS/Sass
  • playcode.io - JS/Typescript/Coffee/LiveScript/Babel/CSS/Sass/LESS/Stylus/HTML/Pug
  • SQLite File Format Viewer - Explore SQLite file format internals
  • SQLite Playground - SQLite sandbox

Presentation

  • Ray.so - Create beautiful images of code snippets.
  • snapify - Snappify enables you to create stunning presentations, with first-class support for code snippets.

Regex

  • Debuggex - PCRE/Python/JavaScript regex matching.
  • ExtendsClass - PHP/Python/Ruby/JavaScript regex matching.
  • Regexr - JavaScript regex matching.
  • Regulex - JavaScript Regular Expression Visualizer.

Transformation

  • AST Explorer - Parse JS to an explorable AST tree via acorn, babel, babylon, espree, esprima, recast, shift, and typescript.
  • Babel REPL - The compiler for next generation JavaScript
  • ByteTools JWT Decoder - Decode and inspect JSON Web Tokens securely. 100% client-side processing, never sends tokens to servers.
  • ByteTools URL Encoder - Encode and decode URLs safely. Perfect for handling query parameters and API endpoints.
  • Compiler Explorer - Run compilers interactively from your web browser and interact with the assembly
  • CSV to JSON & JSON to CSV - Convert between CSV and JSON formats
  • EpochPilot - Convert Unix timestamps, compare timezones, and parse cron expressions. 100% client-side.
  • fixmyjs - Automatically fix your JS, driven by JSHint.
  • JavaScript Deobfuscator - A simple but powerful deobfuscator to remove common JavaScript obfuscation techniques.
  • JSON ABC - Sorts JSON alphabetically
  • JSON to XML Converter - Convert JSON data to XML format with proper formatting and structure
  • JSONFormatOnline - Format, validate and convert JSON locally in the browser, no data sent to servers.
  • Markdown to HTML - Paste or type your markdown and see it rendered as HTML. Download or copy the resulting HTML.
  • Markdown Tools - Tools to convert Markdown to/from a number of formats. E.g. Html to Markdown, or a CSV to a Markdown table.
  • Sovereign Base64 Forge - Encode and decode Base64 strings instantly in the browser.
  • Sucrase - Super-fast Babel alternative
  • SWC - compile JS/TS files using modern JS features and outputs valid code that is supported by all major browsers.
  • Terser - JavaScript parser, mangler and compressor toolkit for ES6+
  • TypeScriptToLua - TypeScript to Lua
  • Web2Img - A tool to bundle your web files into a single image, and extract them via Service Worker at runtime.
  • WebAssembly Explorer - translate C/C++ to WebAssembly, and then see the machine code generated by the browser.

Resources

APIs

Browser Information

CDN

  • JSDelivr - A free CDN for open source projects.
  • Skypack - Load optimized npm packages with no install and no build tools.
  • unpkg - Fast, global content delivery network for everything on npm.

Cheat Sheets

CSS Inliners

Documentation

Glyphs & Icons

  • Copy/Paste Character - Copy & Paste emojis and unicode symbols
  • CSS Icons - Copy & Paste icons in CSS + transition animations!
  • Entity Lookup - Enter any character(s) and find its corresponding HTML entity code.
  • heroicons - Beautiful hand-crafted SVG icons, by the makers of Tailwind CSS.
  • Icon Finder - Millions of graphics for your design projects. Created by independent designers.
  • Icon Monstr - Discover 4000+ free icons in 300+ collections.
  • Icônes - Over 150,000 open source vector icons.
  • Tabler Icons - 4000+ Open source free SVG icons. Highly customizable. No attribution required. For commercial use.

Validation & Parsers

  • Ada URL Parser - WHATWG-compliant and fast URL parser written in modern C++, online.
  • CSP Evaluator - Evaluate CSP rules
  • numverify - Validate phone numbers from over 200 countries.
  • OpenAPI Validator - Validate OpenAPI 3.1, 3.0 & Swagger 2.0 specifications. Paste JSON/YAML, upload files, or fetch from URL.
  • Pythonium - Validate Python code.
  • YAML Validator - Validate YAML syntax with error line numbers, format with custom indentation, and convert to JSON. Client-side processing.

Security

SSL

Test

  • HSTS Preload - Check HSTS preload status and elibility.
  • Mozilla Observatory - A set of tools to analyze your website and inform you if you are utilizing the many available methods to secure it.
  • Security Headers by Probely - An easy to use tool designed to help you better deploy and understand modern security features that are available for your website.
  • Web Check - All-in-one OSINT tool for analysing any website.

License

CC0