Ready to test your HTTP knowledge?
10 mixed questions — guess the meaning of a code or match it to a real-world scenario. The first questions are the everyday codes; it gets harder as you go.
- 10 questions per round, easy → trivia difficulty ramp.
- Build a streak — consecutive correct answers keep your 🔥 going.
- No repeats: play 2 rounds back-to-back with all-new codes.
- Keep playing and older codes slowly return — practice as much as you want.
Tip: use keys 1–4 to answer and Enter to continue.
An HTTP status code is the three-digit number a server returns to describe what happened to a request. There are only a few dozen you meet in day-to-day work, and they fall into five classes: 1xx informational, 2xx success, 3xx redirection, 4xx client errors, and 5xx server errors. This quiz is built for early-career developers and CS students — it starts with the codes you see constantly and works up to the rare ones. Prefer to study first? Flip through the HTTP status flashcards or browse the full status code reference.
How to memorize HTTP status codes
- Learn the five classes first. Once you know 4xx = "you messed up" and 5xx = "the server messed up", half the codes sort themselves.
- Anchor each code to a concrete scenario. A rate limit is 429; a missing page is 404; a crashed handler is 500.
- Use active recall. Re-reading a table does little. Take the quiz a few times, then drill the codes you keep missing with the flashcards.
- Master the confusable pairs. The comparisons below (401 vs 403, 404 vs 410, 429 vs 503) are the ones interviewers love to ask.
Status codes developers confuse
401 vs 403 vs 407
| Code | When it fires | Common cause |
|---|---|---|
| 401 Unauthorized | You are not authenticated | Missing or invalid token / credentials |
| 403 Forbidden | You are authenticated but not allowed | Valid login without permission for the resource |
| 407 Proxy Authentication Required | The proxy needs authentication | Corporate proxy demanding credentials first |
404 vs 410
| Code | When it fires | Common cause |
|---|---|---|
| 404 Not Found | Resource not found (may exist later) | Wrong URL, typo, or not-yet-created resource |
| 410 Gone | Resource intentionally removed for good | Deleted endpoint/content you want crawlers to drop |
429 vs 503
| Code | When it fires | Common cause |
|---|---|---|
| 429 Too Many Requests | You sent too many requests | Hit a rate limit; back off using Retry-After |
| 503 Service Unavailable | The server can't handle requests right now | Overload or maintenance; the whole service is down |
Frequently Asked Questions
What are the most important HTTP status codes to know?
The everyday codes every developer should recognize are 200 OK, 201 Created, 204 No Content, 301 and 302 redirects, 304 Not Modified, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 429 Too Many Requests, 500 Internal Server Error, 502 Bad Gateway, and 503 Service Unavailable. This quiz starts with these high-frequency codes and ramps up to rarer ones.
What is the difference between 401 and 403?
401 Unauthorized means you are not authenticated — you are missing valid credentials or a token, so the server does not know who you are. 403 Forbidden means you are authenticated but not allowed — the server knows who you are and is refusing access to this resource. Rule of thumb: 401 = who are you, 403 = I know who you are and the answer is no.
What is the difference between 301, 302, and 308?
301 Moved Permanently is a permanent redirect; clients and search engines should update to the new URL, and the method may change to GET. 302 Found is a temporary redirect; keep using the original URL. 308 Permanent Redirect is like 301 but it preserves the original HTTP method (a POST stays a POST). Use 301/302 for general redirects and 307/308 when the method must not change.
How do I memorize HTTP status codes?
Learn the five classes first — 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error — then memorize the handful of high-frequency codes in each. Active recall beats re-reading: take the quiz a few times, then use the flashcards for the codes you keep missing. Associating each code with a concrete scenario (a rate limit is 429, a missing page is 404) makes them stick.
Is the HTTP status code quiz free?
Yes. The quiz is completely free, requires no signup, and runs entirely in your browser. Nothing you do is sent to a server; your best score is stored only in your browser's local storage.