HTTP Status Codes Explained for Beginners

An HTTP status code is the server’s compact result for a request. Read it with the response headers and JSON body to decide what succeeded and what to inspect next.

The useful status-code groups

Group	Meaning
2xx	Successful request
3xx	Redirect or further action
4xx	Request or permission problem
5xx	Server-side failure

The codes you will meet first

Code	Meaning	Inspect next
200	Read or update succeeded	JSON body and expected fields
201	A POST created a resource	Save the returned UUID
204	Action succeeded without a body	Do not try to parse JSON
301/308	Redirect	Check the URL and trailing slash
400	Invalid input	Read field and validation details
401	Missing or invalid credentials	Check token presence and type
403	Authenticated but not permitted	Check visibility and scopes
404	Route or resource not found	Copy exact slugs and UUID
409	Conflict	Check duplicate or current state
429	Rate limited	Back off; do not retry immediately
500/503	Server unavailable or failed	Record request ID and retry safely

Inspect status and body together

curl -i "https://meowmeowscratch.com/api/v1/YOUR_USERNAME/weather-station/readings/" \
  -H "Authorization: Bearer $MEOW_APP_API_KEY"Code language: JavaScript (javascript)

The -i option prints the status line and headers before the JSON. A useful error includes a stable code, message, details and request ID. Never log the bearer token while troubleshooting.

A practical diagnostic flow

1. Confirm the scheme, host, API version, username, app slug and endpoint slug.
2. Confirm the method matches the intended operation.
3. Check the trailing slash on management routes.
4. Check the credential type and required scope without exposing its value.
5. Read the JSON error details before changing the payload.
6. For 429 or transient 5xx responses, retry with a bounded exponential backoff.
7. For repeated 5xx responses, record the request ID, time and route for support.

Next step

For a deeper credential and retry flow, read REST API Authentication and Common Errors. To practice each method, return to HTTP Methods Explained.