HTTP Status Code Cheat Sheet

1️⃣ 1xx – Informational

• 100 – Continue: Server received headers, waiting for body
• 101 – Switching Protocols: Used for WebSockets upgrade

Rarely used in support.

2️⃣ 2xx – Success

• 200 – OK: Standard success for GET/POST/PUT
• 201 – Created: Resource successfully created (POST)
• 202 – Accepted: Request accepted but not processed yet
• 204 – No Content: Successful but no data returned (DELETE often)

When to report: 200/201 → good, 202 → may indicate delayed processing.

3️⃣ 3xx – Redirection

• 301 – Moved Permanently: URL permanently changed
• 302 – Found / Temporary Redirect: URL temporarily redirects
• 304 – Not Modified: Browser cached resource, no need to reload

When to report: Only if redirection is causing errors or loops.

4️⃣ 4xx – Client Errors

• 400 – Bad Request: Invalid request syntax; often a bug in front-end or form
• 401 – Unauthorized: User not logged in / missing token
• 403 – Forbidden: User doesn’t have permission
• 404 – Not Found: Resource missing; report if API endpoint missing
• 408 – Request Timeout: Client took too long; intermittent network issues
• 429 – Too Many Requests: Rate limiting; can affect scripts or bots

Most commonly reported in helpdesk: 401, 403, 404, 429.

5️⃣ 5xx – Server Errors

• 500 – Internal Server Error: Generic server error; escalate to devs
• 501 – Not Implemented: Server cannot fulfill request method
• 502 – Bad Gateway: Usually upstream server error / load balancer
• 503 – Service Unavailable: Server temporarily down / maintenance
• 504 – Gateway Timeout: Upstream server failed to respond in time

Report all 5xx errors to devs immediately; include URL, method, timestamp.

Helpful Tips

• Always note: URL, HTTP method (GET, POST, PUT, DELETE), and browser when reporting errors.
• Common relevance: 4xx (authentication/authorization) & 5xx (server misconfig).
• Use DevTools network tab: Can filter by status code to quickly find failed requests.