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Learn to code, one page at a time
Free, original tutorials across HTML, CSS, JavaScript, Python, SQL, Git, Linux, Docker and more — with examples you can run and edit right on the page. No account, no paywall, and 86 developer tools that never send your data anywhere.
- 1,446lessons
- 111courses
- 86tools
How this site is organised
Tracks, then courses, then lessons — so you always know what to read next.
- Tracks group courses by the job you are trying to do: front-end, back-end, databases, DevOps, data and AI.
- Courses cover one subject, ordered from first principles upward, with a sidebar that keeps every lesson in sequence.
- Lessons take one topic each and end with next and previous links, so a course can be read straight through.
Open the full catalogue — 111 courses across 12 tracks.
Course catalogue
Grouped the way developers actually learn: by track.
Python & Data Science
Python itself, plus the web and scientific-computing ecosystem around it.
13 coursesAI & Intelligent Development
Large language models, agent engineering, machine learning and computer vision.
17 coursesFront-end Development
Markup, styling, client-side programming, frameworks and visualisation.
19 coursesBack-end Development
Server-side languages, frameworks and the protocol they speak.
10 coursesDatabases
Relational and NoSQL storage: modelling, querying, indexing.
6 coursesMobile Development
Native and cross-platform apps for phones and tablets.
6 coursesDevOps & Tooling
Version control, containers, pipelines and operations.
8 coursesProgramming Languages
General-purpose languages: syntax, type systems and idioms.
7 coursesComputer Science Fundamentals
Algorithms, data structures, networks, systems — plus everyday developer references.
9 coursesXML & Web Services
Structured data description and inter-system interfaces.
6 courses.NET
The Microsoft stack: web, desktop and data access.
5 coursesBuilding a Website
From a domain name to a live, fast, indexable site.
5 coursesStart with a longer course
The most detailed courses on the site right now.
Python 3
The current Python: syntax, collections, functions and files.
14 lessonsHTML
The structure and meaning of a web page.
14 lessonsCSS
Styling, layout and the cascade.
14 lessonsJavaScript
The programming language of the web.
14 lessonsLaravel
A batteries-included PHP framework.
14 lessonsSQL
Querying, writing and speeding up relational data.
14 lessonsBrowser-only tools
No upload, no account. Everything runs locally in your tab.
Base64 encoder / decoder
Convert text to and from Base64. Runs entirely in your browser — nothing is uploaded.
Hash & checksum
Compute MD5, SHA-1, SHA-256, SHA-384, SHA-512 of text using your browser. No upload.
JSON formatter & validator
Pretty-print, minify, and validate JSON. Runs locally in your browser.
URL encoder / decoder
Percent-encode and decode query strings and path segments. Browser-only.