http status codes for beginners

Think of status codes as responses from the server telling you what happened when you made a request (opened a website, called an API, etc.).

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📦 Status Code Groups (Easy Rule)

Status codes are grouped by their first digit:

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🟡 1xx – Informational (Rarely used)

👉 Server says: “I received your request, processing…”

• Example: 100 Continue

• You’ll almost never handle these directly as a beginner.

📌 Ignore for now

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🟢 2xx – Success

👉 Server says: “All good 👍”

Common ones:

• 200 OK
  ✅ Request successful
  Example: Page loaded, API returned data

• 201 Created
  ✅ Something new was created
  Example: User registered, blog post created

• 204 No Content
  ✅ Success but nothing to return
  Example: Delete API succeeded

🧠 Rule:
If you see 2xx → your request worked

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🔵 3xx – Redirection

👉 Server says: “You’re in the wrong place, go here instead”

Common ones:

• 301 Moved Permanently
  Example: http → https

• 302 Found / Temporary Redirect
  Example: Redirecting to login page

🧠 Rule:
Server is not giving data, it’s redirecting you

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🔴 4xx – Client (Your) Mistake

👉 Server says: “I’m fine, but YOU did something wrong”

This matches your example perfectly 👇

Common ones:

• 400 Bad Request
  ❌ You sent wrong data / malformed request
  Example:

  • Missing required fields

  • Wrong JSON format

🧠 Server exists, API exists, but input is wrong

• 401 Unauthorized
  ❌ You are not logged in
  Example: Missing token

• 403 Forbidden
  ❌ You are logged in, but not allowed
  Example: Trying to access admin data

• 404 Not Found
  ❌ URL or resource does not exist
  Example: Wrong API route

🧠 Rule:
If 4xx → check URL, headers, body, auth

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🔥 5xx – Server Mistake

👉 Server says: “Your request was fine, but I crashed”

Common ones:

• 500 Internal Server Error
  💥 Something broke in backend code
  Example:

  • Null pointer

  • DB query failed

• 502 Bad Gateway
  💥 One server got a bad response from another server

• 503 Service Unavailable
  💥 Server is down or overloaded

🧠 Rule:
If 5xx → backend issue, not your fault

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🧠 Super Simple Memory Trick

2xx → Success
3xx → Redirect
4xx → Your mistake
5xx → Server mistake

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Better version 👇
✅ 400 → Server exists, API exists, but request data is wrong
✅ 404 → Server exists, but URL is wrong

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💡 Real-life Analogy (Restaurant 🍽️)

• 200 → You got your food

• 400 → You ordered nonsense

• 401 → You didn’t pay

• 403 → You’re not allowed inside

• 404 → That dish doesn’t exist

• 500 → Kitchen caught fire 🔥