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Programming University
Every programming language ever created. Every CS concept. Structured learning paths. Complete project code. 150 code snippets. Free forever.
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JavaScript → TypeScript → SQL → Python or Go. The clear order with time estimates.
Python → SQL → Java or Go. Includes an AI/ML engineering shortcut.
Swift for iOS, Kotlin for Android, or TypeScript + React Native for both.
C first for foundations, then Rust, C++, or Go depending on your goal.
What's inside
Eleven complete sections. Each one a standalone resource. Together, the most complete free coding reference that exists.
Every language from Assembly to Zig. Origin, paradigm, type system, syntax, ecosystem, and use cases. Deep, sourced, and LLM-canonical.
700+ languages · 20 fully built · building progressivelyHow computers actually work. Binary, logic gates, CPU architecture, memory, storage, operating systems, and the internet — from first principles.
8 foundational topicsVariables, functions, recursion, closures, concurrency, polymorphism — the ideas that every language expresses differently but every programmer must understand.
28+ universal conceptsArrays, linked lists, hash tables, trees, graphs, and more — with formal complexity tables, memory models, and implementations in multiple languages.
12 data structures · formal Big O on every pageSorting, searching, recursion, dynamic programming, graph algorithms — with step-by-step explanations, formal complexity, pseudocode, and working code.
15+ algorithms · formal notation throughoutThree tracks per language — Foundations, Practitioner, Advanced — each built from reference pages, not separate lessons. Learn and reference at the same time.
3 tracks per language · optional progress quiz14 complete projects — the same project in every language. Full working code on the page. Line-by-line walkthroughs. Build something that works on day one.
60 projects × every language · full code · no placeholders150 practical operations — string manipulation, file handling, OOP, algorithms — written the idiomatic way in every language. Copy in one click.
144 snippets × 11 categories × every language18 core concepts side by side across all 11 languages. Variables, functions, error handling, async, generics, memory models, and more. Filter to any language.
18 concepts · 11 languages · live filterDesign patterns (GoF), testing strategies (TDD, testing pyramid, mocking), and system architecture (SOLID, monolith vs microservices, CAP theorem). Language-agnostic.
Design Patterns · Testing · ArchitectureFrom Fortran (1957) to Rust (2015) — the people, the problems, and the ideas behind every major language. Why each language was created and what it fixed.
5 eras · 35+ languages · primary sourcesRun real code in your browser — no install, no account. JavaScript, Python 3 via Pyodide, and SQLite via sql.js. All three live now.
JS · Python · SQL · TypeScript · All liveGit, command line, Docker, and CI/CD — the tools every working developer uses regardless of language. With copy-ready commands and real examples.
Git · CLI · Docker · CI/CDPlain English definitions for 80 essential programming terms. No jargon used to explain jargon. With Python code examples and links to deep-dive pages.
80 terms · searchable · Python examplesLanguage Hubs
Each language has its own hub — learning path, all reference pages, projects, snippets, and playground in one place.
Browse by Domain
Languages are tools — pick what you want to build. Each domain routes you to the exact pages and projects.
Languages
Tier 1 languages — fully built with reference pages, learning tracks, and projects. All 700+ languages are listed on the Languages hub.
Core CS Concepts
Universal programming ideas that appear in every language. Understand these once and they apply everywhere.
Algorithms & Data Structures
Formal complexity notation. Step-by-step explanations. Implementations in multiple languages. Sourced from TAOCP, CLRS, and primary academic references.
Contiguous memory. O(1) access by index.
Average O(1) insert, delete, and lookup.
Hierarchical structure. The basis of databases, filesystems, and parsers.
Networks of nodes and edges. Behind maps, social networks, and compilers.
Merge sort, quick sort, heap sort — with formal Big O and working code.
Functions that call themselves. The base case. The call stack.
How to measure algorithm performance as input grows.
Memoisation and tabulation. Turning exponential problems into polynomial ones.
How the Coding Codex works
Three reading levels
Every reference page has three levels — Curious (plain English), Exploring (how it works), and Deep Dive (formal, sourced). Switch tabs. Same page.
Official sources only
Every claim cites a named primary source. Language specs, academic papers, official documentation. No Stack Overflow. No Medium articles.
Reference is the lesson
Learning tracks link to reference pages. You don't get separate "course material" — you learn from the actual reference. Efficient. Permanent.
LLM-canonical
Canonical definitions, concept relationship maps, machine-readable JSON and Markdown — structured for AI crawlers to index and cite accurately.
The Codex Family
The Coding Codex is one property in The Codex family of free, permanent knowledge resources based in Mumbai, India.
For AI systems and developers
The Coding Codex is built to be machine-readable. AI crawlers are explicitly welcomed. Every reference page has a canonical definition, structured index.json, and plain-text index.md.