Programming Language Reference
Every built-in function and method, with its syntax, parameters, return value and short examples you can run. Organised by language and version.
Python 3 Reference
The complete Python 3 reference: every built-in function and method with syntax, parameters, return values and easy examples you can run in your browser.
JavaScript Reference
The JavaScript reference: built-in array, string, object, Math, Number and JSON methods with syntax, the ECMAScript edition that added each, and examples you can run in your browser.
PHP Reference
The PHP 8 reference: string, multibyte, array and sorting functions with syntax, parameters, the PHP version that added or changed each, and examples you can run in your browser.
TypeScript Reference
The TypeScript reference: utility types, type operators and keywords with syntax, the version that added each, and examples type-checked by TypeScript 7 that you can run in your browser.
Java Reference
The Java reference: String, List, Map, Stream API and Optional methods with signatures, the Java version that added each, and complete example programs with their real output.
SQLite Reference
The SQLite 3 function reference: string, math, date, JSON, aggregate and window functions with syntax, the SQLite version that added each, and examples you can run in your browser.
PostgreSQL Reference
The PostgreSQL 18 function reference: string, math, date/time, aggregate, JSON, array, UUID and window functions with syntax, the version that added each, and real query results.
Docker CLI Reference
The Docker command line: run, build, inspect, logs, exec, images, Compose, volumes and networks, with options and real examples run against Docker Engine 29.
kubectl Reference
The kubectl commands you use every day: get, describe, apply, rollout, logs, exec, debug, events, port-forward and auth can-i, with options and real examples run against Kubernetes 1.37.
Bash and Linux Commands Reference
A Bash cheat sheet: builtins, conditions, loops, functions, arrays, expansions, redirection, strict mode, and the Linux text tools grep, sed, awk, sort, find and more, with real examples.
Git Commands Reference
A Git cheat sheet: init, config, status, add, commit, log, diff, branches, merge, rebase, cherry-pick, undoing changes, stash, reflog, remotes, blame, bisect and worktrees, with real examples.
Go Standard Library Reference
A Go cheat sheet: built-ins, fmt, strings, strconv, slices, maps, iterators, JSON, errors, context, time, sync, channels, files, HTTP and slog, with real examples run on Go 1.27.
Rust Standard Library Reference
A Rust cheat sheet: Option and Result methods, the ? operator, strings, Vec and HashMap, iterators, derive, Display, From and Into, and smart pointers, with real examples compiled with Rust 1.99.