#1 PDF Application on GitHub that lets you edit PDFs on any device anywhere
Java★ 91,229NOASSERTIONVisit project sitePersonal collection
Useful corners of the internet I keep coming back to.
Tools, references, and working prompts that have proved useful in real work.
More tags
Whiteboards & Diagrams
Excalidrawexcalidraw.comA sketchy shared whiteboard for getting an interface or system idea out quickly.tldrawtldraw.comAn infinite canvas for drawing, diagramming, and building visual ideas together.diagrams.net / draw.ioapp.diagrams.netFor clean flowcharts, database diagrams, and the diagrams that need to be precise.Jotboardjotboard.comA shared online whiteboard for quick visual collaboration.Mermaid Live Editormermaid.aiWrite diagram definitions and preview flowcharts, sequence diagrams, and more in the browser.JSON Crackjsoncrack.comTurns JSON and other structured data into interactive visual maps.
English
BBC Learning Englishbbc.co.ukShort, polished lessons for grammar, vocabulary, pronunciation, news, listening, and speaking, including 6 Minute English.British Council LearnEnglishlearnenglish.britishcouncil.orgFree English exercises organised by skill and CEFR level, from A1 to C1.Cambridge English Activitiescambridgeenglish.orgShort activities across grammar, listening, reading, pronunciation, speaking, vocabulary, and writing from A1 to C2.VOA Learning Englishlearningenglish.voanews.comAmerican English lessons through slower-paced news, podcasts, videos, grammar, and pronunciation.Test-Englishtest-english.comCEFR-based grammar, vocabulary, listening, reading, writing, and Use of English practice with feedback.Perfect English Grammarperfect-english-grammar.comStraightforward grammar reference with free explanations, focused exercises, and downloadable PDFs.EnglishPageenglishpage.comFree grammar and vocabulary lessons, especially thorough on tenses, conditionals, and modals.EnglishClubenglishclub.comFree lessons and practice for grammar, vocabulary, pronunciation, listening, speaking, reading, and writing.ELLLOelllo.orgA large free listening library with natural conversations, transcripts, vocabulary, and quizzes from A1 to C1.Randall's ESL Cyber Listening Labesl-lab.comEveryday listening activities organised by difficulty and topic, with transcripts, quizzes, vocabulary, and speaking tasks.Breaking News Englishbreakingnewsenglish.comFree news-based English lessons with audio, quizzes, and activities across seven difficulty levels.News in Levelsnewsinlevels.comNews rewritten at three English levels, with audio and vocabulary support.Engoo Learning Materialsengoo.comThousands of free study materials for conversation, grammar, business, travel, test preparation, and Daily News. Tutoring is paid.Cambridge Dictionarydictionary.cambridge.orgLearner dictionary with definitions, examples, IPA, British and American audio, and CEFR vocabulary information.Oxford Learner's Dictionariesoxfordlearnersdictionaries.comLearner-friendly definitions, examples, British and American audio, usage notes, and Oxford 3000/5000 vocabulary.YouGlishyouglish.comSearch a word or phrase and hear it in real video clips, filtered by accents such as US, UK, Australian, and Canadian.Forvoforvo.comCommunity pronunciation dictionary for words, names, and places in many languages, including English.Write & Improvewriteandimprove.comA free Cambridge-developed writing tool with automatic feedback and an estimated CEFR level.EF SETefset.orgFree online English assessment with a CEFR result and free EF SET certificate.Readlangreadlang.comRead real English, translate unfamiliar words in place, and save vocabulary for flashcard practice. The free plan has feature limits.Language Reactorlanguagereactor.comBrowser extension for studying through YouTube and Netflix with enhanced subtitles, dictionary tools, and playback controls. Some tools require Pro.Ankiapps.ankiweb.netOpen-source spaced-repetition flashcards with free AnkiWeb sync. Desktop and Android are free; the official iOS app is paid.Project Gutenberggutenberg.orgComplete public-domain English books that can be read online or downloaded free, without registration.LibriVoxlibrivox.orgFree public-domain audiobooks, useful alongside the written text for reading and listening practice.ReadTheoryreadtheory.orgAdaptive reading-comprehension practice with passages, quizzes, and progress tracking.Purdue OWLowl.purdue.eduUniversity writing guidance for grammar, essays, academic writing, research, citations, and professional writing.Academic Phrasebankphrasebank.manchester.ac.ukUniversity of Manchester reference for useful phrases across academic introductions, methods, results, comparisons, and conclusions.Tatoebatatoeba.orgFree, open database of example sentences and translations for seeing words used in context.TED Talksted.comAuthentic advanced English across science, technology, psychology, and business, usually with subtitles and interactive transcripts.
Reading & Summarization
Digitalbook.iodigitalbook.ioFree public-domain eBooks and audiobooks in one searchable catalogue.A Good Movie to Watchagoodmovietowatch.comFilm recommendations with filters for English-language titles and free-to-watch options where available.Notesnooknotesnook.comA privacy-minded, open-source note-taking option worth keeping in the toolkit.
Development Utilities
DevDocsdevdocs.ioFast, searchable documentation for many developer APIs in one interface.regex101regex101.comA regex tester with explanations, match highlighting, and language-specific flavours.Hoppscotchhoppscotch.comA lightweight API-development client for testing HTTP, GraphQL, and WebSocket requests.roadmap.shroadmap.shCommunity learning roadmaps and practical guides for developers.shadcn/uiui.shadcn.comOpen, composable UI components and patterns for building web interfaces.Squooshsquoosh.appA browser-based image compressor and format converter.Supabasesupabase.comThe backend platform behind several projects here: Postgres, auth, storage, and more in one place.Vercelvercel.comWhere I look first when a web project needs a fast path from repository to deployment.Cal.comcal.comOpen scheduling infrastructure for booking workflows and calendar coordination.
Image & Design Utilities
Photopeaphotopea.comA browser-based image editor with layered-file support.Openverseopenverse.orgA search engine for openly licensed and public-domain media. Check each asset's individual licence before use.SVG Reposvgrepo.comA large, searchable collection of SVG icons and illustrations.Iconifyiconify.designA unified icon library. Individual icon sets can have different licences, so check the set before use.Mobbinmobbin.comA reference library of real product interfaces and user flows.Motion BGsmotionbgs.comA source of motion backgrounds for presentations and web work.
Free Learning
PhETphet.colorado.eduInteractive science simulations I use when an abstract idea needs something to move.GeoGebrageogebra.orgFor graphing, geometry, and making maths feel less fixed on a page.MIT OpenCourseWareocw.mit.eduFree course material from MIT. It provides learning materials, not certificates.Learn Anythinglearn-anything.xyzA community-built map of learning paths and useful resources.Google Career Certificatesskills.googleGoogle's collection of career-certificate learning programmes.Instructablesinstructables.comStep-by-step projects and practical how-to guides from a large maker community.Animagraffsanimagraffs.comDetailed animated explainers for understanding how complex things work.Human Benchmarkhumanbenchmark.comShort tests for memory, reaction time, attention, and other cognitive skills.
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From my GitHub stars
Projects I want to keep an eye on.
Selected favorites, with their official sites where I have saved one.
See more on my starred page on GitHubA collective list of free APIs
Python★ 474,823MITVisit project siteOpen-source AI penetration testing tool to find and fix your app’s vulnerabilities.
Python★ 60,315Apache-2.0Visit project siteA simple image/video to Desmos graph converter run locally
Python★ 719GPL-3.0Visit project siteTaste-Skill - gives your AI good taste. stops the AI from generating boring, generic slop
JavaScript★ 83,929MITVisit project siteBeautiful local-first flashcards.
TypeScript★ 32Visit project siteEnhanced ChatGPT Clone: Features Agents, MCP, Skills, DeepSeek, Anthropic, AWS, OpenAI, Responses API, Azure, Groq, o1, GPT-5, Mistral, OpenRouter, Vertex AI, Gemini, Artifacts, AI model switching, message search, Code Interpreter, langchain, DALL-E-3, OpenAPI Actions, Functions, Secure Multi-User Auth, Presets, open-source for self-hosting. Active
TypeScript★ 42,769MITVisit project siteScheduling infrastructure for absolutely everyone.
TypeScript★ 48,120MITVisit project site🔥🔥🔥 Open-source Jira, Linear, Monday, and ClickUp alternative. Plane is a modern project management platform to manage tasks, sprints, docs, and triage.
TypeScript★ 58,836AGPL-3.0Visit project siteA full-featured download manager.
TypeScript★ 55,065NOASSERTIONVisit project siteOpen source, privacy-first web analytics. Lightweight, cookie-free Google Analytics alternative. Self-hosted or cloud.
Elixir★ 28,857AGPL-3.0Visit project siteTurn your Telegram account into an unlimited, secure cloud storage drive. an Open-source desktop app built with Tauri, Rust, and React.
TypeScript★ 5,007NOASSERTIONVisit project siteLexical is an extensible text editor framework that provides excellent reliability, accessibility and performance.
TypeScript★ 23,825MITVisit project siteWrite beautiful documentations with Nuxt and Markdown.
TypeScript★ 3,028MITVisit project siteEasy to maintain open source documentation websites.
TypeScript★ 66,166MITVisit project siteConnect APIs, remarkably fast. Free for developers.
JavaScript★ 11,668NOASSERTIONVisit project siteCheckers to test your internet provider for censorship.
Go★ 1,979Apache-2.0Visit project siteA single-file relational spreadsheet for you and your agent.
TypeScript★ 3,183AGPL-3.0Visit project siteGitNexus: The Zero-Server Code Intelligence Engine - GitNexus is a client-side knowledge graph creator that runs entirely in your browser. Drop in a git repository (Github, Gitlab, Azure, Local) or ZIP file, and get an interactive knowledge graph with a built in Graph RAG Agent. Perfect for code exploration
TypeScript★ 46,947NOASSERTIONVisit project siteOpen Source Qualtrics Alternative
TypeScript★ 12,868NOASSERTIONVisit project siteOpen-Source Form Builder
TypeScript★ 8,962AGPL-3.0Visit project siteContest Management System
Python★ 1,035AGPL-3.0Visit project siteDocumentation that simply works
Python★ 27,375MITVisit project site100+ open-source clones of popular sites like Airbnb, Amazon, Instagram, Netflix, Tiktok, Spotify, Whatsapp, Youtube etc. See source code, demo links, tech stack, github stars.
Code★ 36,711AGPL-3.0Visit project siteFast, accurate & comprehensive text measurement & layout
TypeScript★ 50,161MITVisit project siteTiny, Fast, and Deployable anywhere — automate the mundane, unleash your creativity
Go★ 29,933MITVisit project siteBring projects, wikis, and teams together with AI. AppFlowy is the AI collaborative workspace where you achieve more without losing control of your data. The leading open source Notion alternative.
Dart★ 76,231AGPL-3.0Visit project siteZotero is a free, easy-to-use tool to help you collect, organize, annotate, cite, and share your research sources.
JavaScript★ 15,145NOASSERTIONVisit project site🚀 I Built a Google Jamboard Clone using React.js, Node.js, Express.js, MongoDB! 🚀
TypeScript★ 11Visit project siteSilkBoard is an open-source collaborative whiteboard that offers a free, transparent alternative to proprietary tools, giving users full control over data, customization, and real-time collaboration—without subscriptions or paywalls.
JavaScript★ 5UnlicenseVisit project siteOpenBoard is a cross-platform interactive whiteboard application intended for use in a classroom setting.
C++★ 3,033GPL-3.0Visit project siteOnline collaborative Whiteboard that is simple, free, easy to use and to deploy
JavaScript★ 2,637AGPL-3.0Visit project siteA drop-in shim to allow you to use existing html5 drag'n'drop code with mobile browsers
TypeScript★ 612MITVisit project siteThis is a repository created for the list of resources for learning and exploring Wonderful Polish language.
Code★ 50Visit project sitedraw.io is a JavaScript, client-side editor for general diagramming.
JavaScript★ 7,905Apache-2.0Visit project siteYour own personal AI assistant. Any OS. Any Platform. The lobster way. 🦞
TypeScript★ 388,719NOASSERTIONVisit project siteTHE Copilot in Obsidian
TypeScript★ 7,671AGPL-3.0Visit project siteCommunity plugins list, theme list, and releases of Obsidian.
Code★ 21,301Visit project site📘 Simple and secure journal app
TypeScript★ 1,090MITVisit project sitePresentation Slides for Developers
TypeScript★ 48,406MITVisit project siteOnline quiz/exam taking application.
JavaScript★ 312NOASSERTIONVisit project siteUmo Editor is an open-source document editor based on Vue3 and Tiptap3, providing an online editing experience similar to Microsoft Word.
Vue★ 1,588MITVisit project siteEjudge programming contest management system
C★ 233GPL-2.0Visit project siteOpen-source SRS
JavaScript★ 407MITVisit project siteMiro Developer Platform App Examples
JavaScript★ 422MITVisit project siteOpen Source Inventory Management System
Python★ 7,498MITVisit project siteOpen Source Inventory Management
JavaScript★ 1,530GPL-3.0Visit project siteSuiteCRM - Open source CRM for the world
PHP★ 5,714AGPL-3.0Visit project siteZeppelin is a moderation bot for Discord, designed with large servers and reliability in mind.
TypeScript★ 453NOASSERTIONVisit project siteAI prompts
Prompts I keep coming back to.
Personal working notes for research, opportunity-finding, email organization, and product critique.