HTTP methods, status codes, and headers
By the end of today you can read a raw request and response and explain every line, choose the correct method and status code for an operation, and say what makes a request safe or idempotent.
YesterdayOn Day 23 you watched a request and response fly past in curl output. Today you learn to read every line of it.
TomorrowTomorrow, the data inside those requests, and what makes a set of endpoints a coherent API.
Why this matters
HTTP is the contract every web system speaks, including the LLM APIs you call on Day 69. Choosing the wrong status code is how a retry turns one charge into three.
- HTTP methods
- Status codes
- Headers and cookies
- Idempotency
Learn it
75 minCopy this into Claude or ChatGPT. It quizzes you before it explains anything, which is deliberate. The resources under it are how you check what it told you.
Today's Master Prompt
Free · sign inA prompt written for this day alone: your level, the exact scope, what to leave out, and an instruction to quiz you before it explains anything. Paste it into Claude or ChatGPT and it teaches you today's material.
Check it against something that is not a model
An assistant can be fluent and wrong, and on a topic you met today you will not catch it. These cover the same ground and were made by people who do this for a living, so they are what you hold the explanation up against. They are other people's work and we only link to them, so judge them for yourself.
5 hand-picked resources
Free · sign inVideos, official docs and articles covering the same ground, each opened and annotated by hand. They are what you check the assistant against on a day you cannot yet catch it being wrong.
Build it
40 minUsing curl against a public test API, make a GET, a POST, a PUT and a DELETE, and record the status code returned by each. Then deliberately trigger a 404 and a 400 and read the difference in the response body. Finally write down, for a hypothetical 'place order' endpoint, which method and status code you would use and why retrying it is or is not safe.
Recall it
25 minAnswer out loud, reveal, then mark honestly whether you had it. That score is the only thing on this page you do not get to choose.
5 recall questions
Free · sign inQuestions you answer from memory, then grade yourself against the real answer. The score is carried into the mastery rating below it, so an honest miss cannot quietly become a tick.
Rate it
Completion and mastery are tracked separately. Be honest, because an inflated rating only means the concept resurfaces sooner.
Mastery tracking
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Recap
- 01A request is a method, a path, headers and an optional body
- 02Idempotency is what makes retrying safe, and networks make retries inevitable
- 03401 is who are you; 403 is not you
- 04Content-Type tells the receiver how to read the bytes
Your progress
Free · sign inMark days complete, pick up where you left off across devices, and watch completion and mastery diverge. Free, and the account exists only so ninety days of work cannot vanish with a cleared browser.