Cheat sheets

One page per technology: the snippets you actually look up, grouped by topic and pulled from the full courses on this site. No sign-up, no tracking, and each page prints as a single reference sheet.

Python & Data Science

Python 3 cheat sheet

The current Python: syntax, collections, functions and files

NumPy cheat sheet

The array library nearly all scientific Python builds on

pandas cheat sheet

Tabular data loading, cleaning and aggregation

Matplotlib cheat sheet

The standard plotting library for Python

Jupyter Notebook cheat sheet

Interactive, reproducible analysis in the browser

Flask cheat sheet

A small, explicit Python web framework

FastAPI cheat sheet

Typed, async API framework built on type hints

Django cheat sheet

Batteries-included framework with an ORM and admin

SciPy cheat sheet

Optimisation, integration, statistics and signal processing

Pillow cheat sheet

Image loading, resizing and format conversion

Python 2.x cheat sheet

The legacy version you may still meet in old codebases

R cheat sheet

A language built for statistics and data analysis

Julia cheat sheet

High-performance language for numerical computing

AI & Intelligent Development

AI Basics cheat sheet

What machine intelligence is and how the pieces fit together

AI Agents cheat sheet

Models that take actions in a loop instead of only answering

Math for AI cheat sheet

Linear algebra, probability and calculus as actually used

Machine Learning cheat sheet

Learning patterns from data: training, validation, overfitting

scikit-learn cheat sheet

The classic toolkit for tabular machine learning

TensorFlow cheat sheet

An end-to-end machine learning platform

PyTorch cheat sheet

Tensors, autograd and neural networks in Python

Natural Language Processing cheat sheet

Working with text: tokens, embeddings and transformers

LangChain cheat sheet

Pipelines for LLM applications: prompts, tools, memory

Ollama cheat sheet

Run open models locally, offline

OpenCV cheat sheet

Image processing and computer vision

Codex cheat sheet

AI pair programming that edits code from instructions

Claude Code cheat sheet

An agentic coding assistant in your terminal

OpenCode cheat sheet

An open-source agentic coding assistant

Vibe Coding cheat sheet

Building software primarily through natural language

Selenium cheat sheet

Driving real browsers for tests and scraping

Playwright cheat sheet

Modern browser automation and end-to-end testing

Front-end Development

HTML cheat sheet

The structure and meaning of a web page

CSS cheat sheet

Styling, layout and the cascade

JavaScript cheat sheet

The programming language of the web

TypeScript cheat sheet

JavaScript with a type checker in front of it

HTML DOM cheat sheet

Reading and changing the document from script

AJAX cheat sheet

Talking to a server without reloading the page

JSON cheat sheet

The data format that APIs actually speak

Tailwind CSS cheat sheet

Utility-first styling inside your markup

Bootstrap 5 cheat sheet

A ready-made responsive component framework

Foundation cheat sheet

Another mature responsive front-end framework

Vue.js cheat sheet

A progressive framework with reactive templates

React cheat sheet

Component-based UI with a virtual DOM

Next.js cheat sheet

Full-stack React with routing and server rendering

Angular cheat sheet

An opinionated, complete front-end platform

jQuery cheat sheet

The classic DOM and Ajax convenience library

ECharts cheat sheet

Rich interactive charts with a declarative config

Chart.js cheat sheet

Small, friendly canvas charts

SVG cheat sheet

Vector graphics described as markup

Font Awesome cheat sheet

An icon set you can drop into any page

Back-end Development

Node.js cheat sheet

JavaScript on the server: modules, files, HTTP

PHP cheat sheet

The classic server-side scripting language

Java cheat sheet

The JVM language behind a huge share of enterprise software

HTTP cheat sheet

Requests, responses, caching and CORS

Go cheat sheet

A small language built for concurrency and simple deployments

Rust cheat sheet

Memory safety without a garbage collector

Spring Boot cheat sheet

Convention-driven Java services

Laravel cheat sheet

A batteries-included PHP framework

Ruby cheat sheet

A language optimised for programmer happiness

GraphQL cheat sheet

Client-specified queries instead of fixed endpoints

Databases

SQL cheat sheet

Querying, writing and speeding up relational data

MySQL cheat sheet

The most widely deployed open-source database

PostgreSQL cheat sheet

A feature-rich object-relational database

MongoDB cheat sheet

Document storage with a flexible schema

Redis cheat sheet

In-memory data structures for caching and queues

SQLite cheat sheet

A complete database in a single file

Mobile Development

Android cheat sheet

Native Android development

iOS cheat sheet

Building apps for iPhone and iPad

Flutter cheat sheet

One codebase, compiled UI for every platform

React Native cheat sheet

React components rendered as native views

Kotlin cheat sheet

The modern default language for Android

Swift cheat sheet

Apple's language for its platforms

DevOps & Tooling

Git cheat sheet

Distributed version control without the fear

Linux cheat sheet

The shell, permissions, processes and services

Docker cheat sheet

Package an app with its dependencies as a container

Kubernetes cheat sheet

Scheduling and scaling containers across machines

Nginx cheat sheet

Reverse proxy, TLS termination and static files

CI / CD cheat sheet

Automated build, test and deploy pipelines

Bash Scripting cheat sheet

Automating everyday command-line work

Ansible cheat sheet

Agentless configuration management

Programming Languages

C cheat sheet

The language of operating systems and embedded work

C++ cheat sheet

C with objects, templates and the standard library

C# cheat sheet

The main language of the .NET ecosystem

Scala cheat sheet

Functional and object-oriented, on the JVM

Lua cheat sheet

A tiny language designed to be embedded

Dart cheat sheet

The language behind Flutter

Computer Science Fundamentals

Algorithms cheat sheet

Searching, sorting and complexity analysis

Data Structures cheat sheet

Arrays, lists, trees, hash tables and their trade-offs

Computer Networks cheat sheet

Layers, TCP/IP and what happens on a request

Operating Systems cheat sheet

Processes, memory, files and scheduling

Character Encodings cheat sheet

Base64, URL encoding and UTF-8 explained plainly

Hashing & Checksums cheat sheet

MD5, SHA-1, SHA-256 and password hashing

Data Formats cheat sheet

JSON and CSV: shape, rules and conversion

Dates & Time cheat sheet

Timestamps, UTC and time-zone traps

Regular Expressions cheat sheet

The regex constructs you actually use

XML & Web Services

XML cheat sheet

Markup for arbitrary structured data

XPath cheat sheet

Addressing nodes inside an XML document

XSLT cheat sheet

Transforming XML into other formats

SOAP cheat sheet

XML-based web services and WSDL contracts

RESTful APIs cheat sheet

Resource-oriented API design

RSS & Atom cheat sheet

Syndication feeds and readers

.NET

.NET cheat sheet

The cross-platform runtime and tooling

ASP.NET Core cheat sheet

Web APIs and apps on .NET

LINQ cheat sheet

Querying collections, objects and databases from C#

WinForms cheat sheet

Classic Windows desktop applications

WPF cheat sheet

Declarative desktop UI with XAML

Building a Website

SEO Basics cheat sheet

Helping search engines understand and index you

Domains & DNS cheat sheet

Name resolution and the records that matter

Web Hosting cheat sheet

Static, container and serverless deployments

CDNs & Caching cheat sheet

Serving fast from an edge near the visitor

Accessibility cheat sheet

Building sites everyone can use