See the difference. Then understand it.
Diffreel is a hobby project with one goal: help people understand things by seeing them move. Some ideas never quite land as a paragraph — how a cache fills and empties, why one protocol waits and the other does not — but they land in a few seconds once you watch the two sides run next to each other.
So every reel here is a short animation that takes one comparison — cache-aside versus write-through, TCP versus UDP — and plays both sides at once. Side A is always vermillion, side B is always cyan, on every reel, everywhere on this site. You learn the colors once and never have to read a legend again.
Under a reel there is often an article. That is the blog half of this place: the reel shows you the shape of an idea in forty-five seconds, and the article walks you through why it is shaped that way, in plain words, with the figures and tables a short loop has no room for. Watch first, read second, or the other way round.
Everything is free and every reel has its own link, so send one to a colleague who is stuck on the same question, drop it in a code review, or put it in your notes. If it helped you understand something, that is the whole point.
Under the hood, each reel is a single HTML file of about 30 KB with no outside requests — it runs sandboxed on a separate origin and works with the network unplugged. View source on any reel. It is all there, in one file.