What is 304 not modified caching?

One-second resolution: HTTP dates have second granularity. If a resource changes twice within the same second, the second change might not be detected.
Clock skew: If the server's clock shifts (NTP corrections, server migration), Last-Modified timestamps can be inconsistent.
Regenerated content: A file might be regenerated with the same content but a new timestamp. ETag would correctly return 304; Last-Modified would incorrectly return 200.

Understanding HTTP 304 Not Modified and Conditional Caching is a common topic when working with HTTP and APIs. Understanding it helps you diagnose issues and choose the right status codes and headers. Use our Header Inspector and AI Inspector to analyze your requests and responses.

How can I debug 304 not modified caching?

Use the Header Inspector to inspect request and response headers, the Status Analyzer to send live requests, and the AI Inspector to get recommendations. Check the Knowledge Center for more guides.

Which tools on HttpStatus.com help with 304 not modified caching?

Header Inspector, Redirect Checker, AI Inspector, and the API Client are useful. Visit the relevant hub (e.g. CORS Hub, Redirect Hub) for more tools and references.

Where can I learn more about HTTP status codes?

Visit the Status codes reference and the HTTP Hub on HttpStatus.com for full documentation and interactive tools.

Understanding HTTP 304 Not Modified and Conditional Caching