109 languages, one tab
Frontend frameworks, systems languages, databases and scripting, all behind the same instant editor.
109 languages · runs in your browser
Write, run and share code in every language straight from your browser.
No installs, no accounts, no waiting. A fast, beautiful playground for Python, JavaScript, Rust, Go, C++, SQL and 100+ more — with instant output beside your code.
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- Phone, tablet & desktop
Instant output
Hit Run and see the result immediately — stdout, stderr and execution stats right next to your code.
Install it as an app
Add the app to your home screen or dock — it opens full-screen like a native one.
Keeps working offline
The interface is cached after your first visit, so the playground loads instantly even on a weak connection.
Choose your stack
Nine families — web and scripting, UI frameworks, databases, systems languages — each opening a real editor, not a text box.
Take it with you
On iPhone, iPad, Android, Windows and Mac — full-screen, fast to launch, and always up to date.
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Start with Python, JavaScript, or anything else in the catalogue. It takes a second.
Start codingLearn by doing
Short, hands-on courses that run in the same editor as the compilers. Nothing to install, no account, and your progress is saved in this browser.
HTML from the ground upLearn markup by writing itStart courseCSS from the ground upMake it look the way you meanStart courseJavaScript from the ground upMake the page do somethingStart coursePython from the ground upYour first programming languageStart courseRuby from the ground upA language designed to make programmers happyStart courseLua from the ground upA tiny language that goes almost everywhereStart courseScheme from the ground upA language of lists, where the code is the dataStart courseProlog from the ground upTell the computer what is true, and let it searchStart courseR from the ground upThe language statisticians reach for when the data arrivesStart courseTypeScript from the ground upSay what your code meansStart courseSQL from the ground upAsk the data a questionStart courseRust from the ground upFast code the compiler checksStart courseC from the ground upThe small language under everything elseStart courseC++ from the ground upThe language behind fast software, one file at a timeStart courseGo from the ground upSimple code that runs at scaleStart courseJava from the ground upThe language that runs almost everywhereStart courseBash from the ground upThe shell, one script at a timeStart courseKotlin from the ground upThe modern language on the Java virtual machineStart courseC# from the ground upThe language of .NETStart courseSwift from the ground upThe language of Apple, and beyondStart courseHaskell from the ground upValues, functions and types that keep their promisesStart courseClojure from the ground upA Lisp where the data never changes under youStart courseElixir from the ground upUnchanged data, small functions, and a pipe that reads left to rightStart courseDart from the ground upThe language behind Flutter, from the first line to a reportStart coursePerl from the ground upThe language that made text processing a one-linerStart courseScala from the ground upOne language for scripts and servicesStart courseReact from the ground upInterfaces built from functionsStart coursePHP from the ground upThe language behind the web pageStart coursePostgreSQL from the ground upThe database the web is quietly built onStart coursex86-64 assembly from the ground upThe language the processor actually runsStart courseD from the ground upThe speed of C with the comfort of a modern languageStart courseErlang from the ground upSmall modules, matching instead of assignment, and no loops in sightStart courseFortran from the ground upThe language of formulas, still the fastestStart courseF# from the ground upValues that never change, and functions that fit togetherStart courseGroovy from the ground upJava's power, with the ceremony left outStart courseOCaml from the ground upAn expression language with types that catch you earlyStart coursePascal from the ground upThe teaching language that still compilesStart courseLangChain from the ground upChains, prompts, parsers and toolsStart courseRAG from the ground upRetrieval that actually finds the answerStart courseEvaluating AI systemsNumbers instead of opinionsStart courseLangGraph from the ground upWorkflows that loop, pause and resumeStart coursePrompt engineering from the ground upInstructions that survive contact with usersStart courseAI agents from the ground upLoops that act, stop and stay inside their permissionsStart courseVector databases from the ground upIndexes, filters and recall you can measureStart courseLLM APIs from the ground upRequests, retries and bills you can reason aboutStart courseModel Context Protocol from the ground upOne wire between a model and the tools it may useStart courseGuardrails and safetyDecisions around the model, not instructions inside itStart courseObservability for AI systemsSee what the model did, and what it costStart courseFine-tuning and LoRATeach a model one behaviour without teaching it everything againStart courseTransformers from the ground upThe block, one matrix at a timeStart courseClassical machine learningModels you can fit, read and checkStart courseDeep learning from the ground upNetworks built from numbers you can checkStart courseComputer vision from the ground upImages as numbers you can seeStart courseRecommender systems from the ground upRank a catalogue for one user at a timeStart courseMLOps from the ground upShip a model, watch it, and take it back safelyStart courseReinforcement learning from the ground upRewards, values and policies, computed by handStart courseSpeech and audio from the ground upSamples, spectra and the words they carryStart courseDiffusion models from the ground upAdd noise, learn to undo it, and sampleStart course