HeaderShim

Modify HTTP request and response headers with scoped rules and switchable profiles.

HeaderShim sets, appends, and removes HTTP request and response headers using rules you write. Each rule is scoped to the sites you choose and applies only after you grant HeaderShim access to those sites. - See what HeaderShim is set to change on the site you are looking at. Opening the popup on a site reads that tab's address and reduces it to an origin (scheme, host, and port), to show what HeaderShim has configured for that hostname and prefill a new rule's scope. The About page lists the read against the activeTab permission. - Set, append, and remove request and response headers. Chrome reserves some header names and allows request appends on only 21 headers. The editor flags a rule Chrome rejects and says why. - Scope a rule to specific domains, a URL pattern, an RE2 regular expression, or all sites. The Grant button names the site access a rule needs before you approve it. - Group rules into profiles. Switch profiles from the popup, or jump to the previous profile with Alt+Shift+K. Open the popup with Alt+Shift+H and pause every rule with Alt+Shift+P. - Grant site access one site at a time, when a rule needs it. The Site access page also offers access to all sites in one step, and revokes any grant. - Add a header to a single tab without saving a rule. - Import and export profiles and their rules as JSON. HeaderShim reads its own export format and ModHeader-format JSON files, and the import summary lists what it changed or dropped. Settings, the active profile selection, and tab overrides are not part of an export. - Start over in Settings replaces your configuration with a new empty Default profile and default settings, revokes all site access, and clears any this-tab changes.