OpenModHeader

Provides the features of the infamous ModHeader extension, but without any malware :D.

Header editing

• Set, append, or remove headers on both requests and responses
• Enable or disable any single header without deleting it
• Live count of active headers on the toolbar badge

Profiles

• Unlimited independent header sets, each with its own name and colour
• All enabled profiles apply at once, so you can layer an auth-token profile over a feature-flag profile
• Duplicate, rename, recolour, and delete from the profile menu

URL filtering

• URL contains — plain substring match
• URL matches regex — full regular expression
• Exclude domains — skip named domains and their subdomains
• Resource types — restrict to xmlhttprequest, main_frame, script, and so on
• Leave filters empty and the profile applies everywhere

Everything else

• Global on/off switch, plus Alt+Shift+H from anywhere
• Export and import profiles as JSON to share a setup or check it into a repo
• Open the popup in a full browser tab when you're editing a lot at once
• Follows your system light/dark theme
• Warns you before saving a rule the browser will reject

You may download directly from the source here if concerned about security.