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

Inspired by the awesome list thing.

• 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.

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

• 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.

• Ceaser - CSS easing animation tool with cubic-bezier curves.
• Clippy - CSS clip-path maker and editor.
• Responsive Patterns - Collection of responsive web design patterns.
• transition.css - Drop-in CSS transitions
• Type Fluidity - Fluid typography clamp value generator

• Babel Time Travel - Travel in time as babel transpiles.
• DebugJS - Debug your JavaScript in the browser (lol?)
• httpbin - HTTP Request & Response service.
• JavaScript Visualizer 9000 - Loupe-inspired JavaScript execution visualizer
• JSONBIN.io - Custom, mock JSON API
• Loupe - Similar in goal to SlowmoJS, a JavaScript call stack visualizer.
• SlowmoJS - Execute JavaScript in slow motion.

• 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.

• 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.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)

• 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.

• ASCII Silhouettify - Convert images into ANSI-escaped color ASCII art.
• Favic-o-matic - Literally generates every favicon neccessary + markup.
• JPEG.rocks - Privacy-aware JPEG optimizer
• PNG-to-SVG - Free conversion from JPG or PNG images To vectorized SVG.
• Squoosh - Compress and optimize images in browser
• SVG-to-backgroundImage - Convert your SVG files into CSS url (data URIs) by encoding it.
• SVGOMG - Try SVGO (SVG Optimizer) in the browser!

• Perflink - JS benchmarks

• 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

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

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

• 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.

• API Status Check - Real-time status monitoring for 540+ APIs and services including AWS, Stripe, GitHub, and OpenAI.
• JSONPlaceholder - Free fake API for testing and prototyping.
• Zippopotamus - Zipcode to Geo

• What's My Browser? - Detailed, shareable information about your web browser.

• 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.

• OWASP Cheat Sheet Series - A concise collection of high value information on specific application security topics.

• Campaign Monitor - Inline your CSS for HTML email.
• MailChimp - Inline CSS styles for HTML email templates.

• DevDocs - Basically Dash but a web application and FREE.
• ECMAScript Proposal Stages - Track TC39 ECMAScript proposals by stage.
• ExplainShell - A better way to read MAN pages.

• 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.

• 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.

• Mozilla SSL Configuration Generator - SSL configuration generator for various server software and platforms.
• Self-Signed Certificate Generator - A self-signed certificate generator.

• 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.