Library / Browser dev tools / Status code
No. 111·noun·also called HTTP status, 404, 500

Status code

The three-digit number a server sends back to say whether a request worked, and if not, roughly why.

SPECIMEN · DIAGRAM · COMPARE

2xx

  • It worked
  • 200 OK
  • 201 Created

4xx

  • Request problem
  • 401 · 403 · 404
  • Check address and sign-in

5xx

  • Server broke
  • 500 · 503
  • Check backend logs
Definition

What it is

Every response from a server starts with a status code. They group by first digit:

  • 2xx: it worked (200 OK, 201 Created)
  • 3xx: look somewhere else (a redirect)
  • 4xx: the request was the problem (401 not signed in, 403 not allowed, 404 not found)
  • 5xx: the server broke (500 internal error, 503 unavailable)

The first digit alone tells you where to look. A 4xx usually means a wrong address, a missing sign-in, or a permission issue. A 5xx means the backend crashed, and its logs will say why.

Say it like a builder

How to ask for it

Vague

“It gives an error.”

Precise

“Loading /dashboard returns a 500 from GET /api/stats, but only for accounts with no projects. Check the backend logs for that request and handle the empty case.”

Why it works

A 500 points the agent at the backend, and the pattern (accounts with no projects) points at the likely edge case.

In the wild

You've seen this in

  • P"404 Page not found" pages
  • DThe Status column in the DevTools Network tab
  • I"500 Internal Server Error" screens
Usage note

Often confused with

Error stateA status code is what the server returned; an error state is what the user sees on screen because of it.