MV3 favors declarativeNetRequest (DNR) for performance and privacy. Use rule‑based modifications over request listeners.

Can I modify response headers?

Yes, within DNR’s supported operations. Some headers are restricted; scope rules to specific sites.

Limit scope with URL patterns, avoid sensitive headers unless necessary, and validate via DevTools.

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.

Install for Chrome Manual install How‑to guide

DNR applies rule sets to requests/responses. Prefer per‑site patterns and the minimal set of active rules.