Headerly overview

Headerly is a browser extension for creating reusable network rules. A rule can modify request or response headers, redirect or block a request, allow traffic, or upgrade an insecure URL scheme.

Each rule is stored as a profile with three main parts:

• an action that defines what the browser does;
• conditions that select requests;
• a priority used when profiles overlap.

Headerly uses Chrome's Declarative Net Request API. The browser evaluates and applies registered rules; Headerly manages the profile editor, storage, rule registration, and error reporting.

Common uses

• Add an authorization or feature-flag header during development.
• Select an existing browser cookie and append it to matching requests.
• Change response headers while testing CORS or iframe behavior.
• Redirect an API or asset to another environment.
• Block an unwanted request while debugging a page.
• Limit a rule to one domain, method, resource type, tab, or tab group.
• Export profiles for backup or sharing.

What Headerly does not do

Headerly does not provide a network log, inspect request or response bodies, modify bodies, or act as a system proxy. Browser and DNR restrictions still apply to every profile.

Continue with installation, or create your first profile.