HeaderKit - Modify Request Headers

Create scoped request-header rules for HTTPS sites. Switch profiles, auto-pause sessions, and manage site access locally.

HeaderKit is a focused request-header manager for API development, QA, and web testing. Create custom request headers for exact HTTPS hosts and organize them into profiles. Keep staging, QA, and development setups separate, then switch the active profile without repeatedly editing values or changing application configuration. With HeaderKit, you can: • Add, edit, pause, and delete request-header rules from the current-site popup or Rule Manager. • Create, rename, and duplicate profiles. Apply one profile at a time while keeping other setups saved. • Narrow rules to a path prefix or fetch/XHR requests instead of applying them across an entire host. • Apply a profile until you turn it off, for one hour, for eight hours, or until Chrome closes. • Pause or resume all rules with the master switch or Alt+Shift+X. • Review and revoke site access without deleting saved rules. No all-site access is granted by default. • Detect duplicate rules and overlapping active rules with conflicting header values. • Mask sensitive-looking values in lists and edit forms, with an option to reveal them. • Export profiles and rules as JSON backups. Import copies with every imported rule paused for review. Local settings. Explicit site access. Your profiles, rules, and settings are stored locally in your Chrome profile. HeaderKit has no analytics, advertising, accounts, remote code, or developer operated backend. Active header values are sent only to matching requests on approved exact HTTPS hosts. HeaderKit does not read page content or response bodies, retain browsing history, or send your settings and header values to its developer. HeaderKit modifies request headers, not response headers, and does not bypass CORS. Masking is visual only: local storage and JSON backups contain unencrypted header values. Use authorized test systems and avoid long-lived production credentials.