HTTP Status Codes: What the Server Is Telling Your Program

Every time your program makes an API request, the server responds with more than just data — it responds with a status code. This three-digit number says: “everything’s fine,” “that doesn’t exist,” “access denied,” or “I’m broken.”

Status Code Groups

Status codes are grouped by their leading digit:

The Most Important Codes

200 OK

Everything is fine. Request succeeded, data received.

response = requests.get("https://api.chucknorris.io/jokes/random")
print(response.status_code)  # 200

201 Created

Resource successfully created. You get this in response to a POST request (creating a repository, publishing an article).

204 No Content

Success, but the response body is empty. Typical after deleting a record.

400 Bad Request

The server couldn’t understand your request. Usually means a malformed or invalid parameter.

{"cod": "400", "message": "bad request"}

401 Unauthorized

Not authenticated. API key is missing or invalid.

{"cod": 401, "message": "Invalid API key"}

403 Forbidden

Authenticated, but not authorized. For example, trying to modify someone else’s repository.

404 Not Found

Not found. The URL is wrong or the requested resource doesn’t exist.

{"cod": "404", "message": "city not found"}

422 Unprocessable Entity

Request syntax is correct but the data is invalid (e.g., a date in the wrong format).

429 Too Many Requests

Rate limit exceeded. Wait and try again.

500 Internal Server Error

The server crashed. This is not your fault — the problem is on the service’s end.

502 Bad Gateway / 503 Service Unavailable

Server temporarily unavailable. Try again later.

Handling Status Codes in Python

Option 1 — manual check

response = requests.get(url, params=params)

if response.status_code == 200:
    data = response.json()
elif response.status_code == 404:
    print("Not found")
elif response.status_code == 401:
    print("Invalid key")

Option 2 — raise_for_status()

raise_for_status() automatically raises an HTTPError if the status code is >= 400:

try:
    response = requests.get(url, params=params)
    response.raise_for_status()  # ← raises on 4xx or 5xx
    data = response.json()
except requests.exceptions.HTTPError as e:
    print(f"Error: {e.response.status_code}")

Option 2 is more concise and idiomatic — use it in production code.

The 4xx vs 5xx Rule

• 4xx — you did something wrong. Fix your request.
• 5xx — the server did something wrong. Wait, or contact support.

Practice: Viewing Status Codes in the Browser

1. Open DevTools (F12) → Network tab
2. Navigate to any website
3. Click on any request
4. Find Status Code in the Headers section

You’ll see 200 for successfully loaded resources and 304 (Not Modified, served from cache) for resources that haven’t changed.