Tools & systems

The tools around the code: what they do underneath, and a place to try them without breaking anything.

Code over time

Git, in a sandbox

Type real git commands and watch the commit graph change: branches, merge, rebase, reset and revert.

commit · branch · merge

Open →

Programs that talk

APIs and HTTP

A request and its answer, piece by piece: methods, status codes, JSON, keys and limits.

GET · POST · 429

Open →

Tools for language models: MCP

How a language model asks for a tool to be run, and what MCP standardises.

tool use · MCP

Open →

Data that stays

SQL, in a sandbox

Real queries against a small school database: SELECT, WHERE, JOIN, GROUP BY, and changing the data.

SELECT · JOIN · GROUP BY

Open →

Code that runs anywhere

Docker, in a sandbox

Images built from layers, the build cache, containers with ports and volumes, and the errors Docker really gives.

build · run · -p · -v

Open →