amir tohidlo

Safe Headers Scanner helps WordPress administrators identify common issues that may cause header-related problems. 
The plugin scans installed themes and plugins for: 
* Unnecessary whitespace before <code><?php</code> tags 
* Extra whitespace after closing <code>?></code> tags 
* Direct output (e.g., <code>echo</code>, <code>print</code>) before headers are sent
Results are displayed in a clear report, so you can review and fix potential issues easily.

Safe Headers Scanner

Scan themes and plugins for potential header issues such as whitespace before/after PHP tags or direct output before headers.

zubovd

This plugin adds the ‘Last-Modified’ header to each post and returns the ‘304 Not Modified’ header to the client without a body in the response if he sent the ‘If-Modified-Since’ header and the post has not changed since that date.

Last-Modified and If-Modified-Since Headers

Add Last-Modified anв support If-Modified-Since Headers

Safe Headers Scanner vs Last-Modified and If-Modified-Since Headers