Client Error
HTTP 400 Bad Request
The server could not understand the request due to invalid syntax or malformed data.
Check a URL for HTTP 400
Paste any URL to see whether it currently returns 400. Runs a live HTTP probe and follows redirects.
What does HTTP 400 mean?
HTTP 400 Bad Request means the server cannot process the request because the client sent something invalid — malformed JSON, missing required fields, invalid characters in the URL, or exceeded size limits.
Common Causes
- •Malformed JSON in request body
- •Missing required parameters
- •Invalid URL encoding
- •Request body exceeds size limit
- •Invalid header values
How to Fix It
- 1.Validate request data before sending
- 2.Check for special characters in URLs
- 3.Ensure Content-Type header matches body format
- 4.Review API documentation for required fields
SEO Impact
Pages returning 400 will not be indexed. If users see 400 errors, it indicates a broken form or link.
Related Status Codes
400 Bad Request on your platform
Same status code, different fix depending on where you host. Jump to a platform-specific deep dive:
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