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Python
Variables, types, input, strings, f-strings & 30+ real projects. A taste is free — reveal any locked solution for 10 ⭐, or go full with Premium.
C
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C
Compiling, pointers, structs, manual memory management & real Run/Submit exercises in a live C sandbox. Foundational for systems courses everywhere.
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C++
References, classes, vectors & the STL, with live Run/Submit exercises in a real C++ sandbox.
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Java
Classes, objects, inheritance, ArrayLists & AP CS A-style examples, with live Run/Submit exercises.
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C#
Classes, LINQ & collections — the language behind Unity games and enterprise .NET, with live Run/Submit exercises.
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JavaScript
Arrow functions, array methods (map/filter/reduce), objects & destructuring — runs instantly in your browser, no server needed.
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Visual Basic
Subs, functions & arrays in classic English-like syntax — still huge in enterprise Windows apps, with live Run/Submit exercises.
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SQL
SELECT, JOIN, GROUP BY & more — live queries against a real in-browser database.
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R
Vectors, data frames & statistics functions — the language behind most college stats coursework.
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Rust, Haskell, Racket, OCaml & Scheme
One overview covering five languages from theory, compilers & systems electives — including Rust, one of the fastest-rising languages today.
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Delphi / Object Pascal
Procedures, arrays & records — still running huge amounts of legacy enterprise Windows software, with live Run/Submit exercises.
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Scratch
Sprites, blocks & events — MIT's drag-and-drop visual language that introduces millions of kids to programming.
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Go
Slices, maps, structs & goroutines — the language behind Docker & Kubernetes, with live Run/Submit exercises.
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PHP
Variables, arrays & string functions — the language behind WordPress, with live Run/Submit exercises.
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Swift
Optionals, structs & safety-first syntax — Apple's language for iOS & macOS, with live Run/Submit exercises.
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Ada
Strong typing, procedures & packages — mandated for safety-critical avionics, defense & aerospace systems.
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x86-64 Assembly
Registers, the stack & control flow — the layer C compiles down to. Ties into the CMU systems track.
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MATLAB
Matrices, vectorized operations & plotting — standard in most engineering departments. Proprietary/licensed, so no free execution; see GNU Octave.
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Fortran
The oldest major language still in active use — runs weather models & scientific supercomputing, with live Run/Submit exercises.
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Ruby
Blocks, arrays & hashes in famously readable syntax — the language behind Ruby on Rails, with live Run/Submit exercises.
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Objective-C
Classes, messages & properties — the language that built iOS/macOS before Swift, still huge in legacy Apple code.
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TypeScript
Types, interfaces & generics on top of JavaScript — the default for large-scale modern web apps, with live Run/Submit exercises.
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PowerShell
Pipelines, cmdlets & object-based scripting — Microsoft's automation shell for Windows IT work, with live Run/Submit exercises.
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VBA
Macros & the Excel object model — the automation language built into every copy of Office.
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Kotlin
Null safety, data classes & JVM interop — Google's preferred language for Android, with live Run/Submit exercises.
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Dart
Null safety & classes — Google's language behind Flutter, for shipping iOS/Android/web from one codebase, with live Run/Submit exercises.
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Lua
Tables & functions in a tiny embeddable language — behind Roblox, WoW addons & game scripting, with live Run/Submit exercises.
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HTML & CSS
Structure, flexbox, grid & responsive design — with a live playground that renders your code as you type.