DNR basics
DNR applies rule sets to requests/responses. Prefer per‑site patterns and the minimal set of active rules.
Examples
- Set a custom header for a domain
- Append a value without overwriting
- Remove a header for specific paths
Manifest V3 Header Editor: Modify Headers with DNR
Understand how to set/append/remove headers in MV3 using declarativeNetRequest, and when it won’t work.
TL;DR: MV3 favors rule‑based declarativeNetRequest. Scope rules per site, avoid overly broad matches, and validate in DevTools.
