Header Override vs MarklyKit

A side-by-side comparison built from both listings. Blank cells mean the company has not given that detail; we never guess.

Header Override compared with MarklyKit
Detail	Header Override	MarklyKit
What it does	Open-source browser extension to modify HTTP request and response headers and cookies	Browser extension for highlighting, annotating, and taking notes on any webpage
Stage	Not given	Not given
Founded	Not given	Not given
Based in	Not given	Not given
Pricing model	Open source	Freemium
Pricing	Not given	Free plan includes unlimited highlighting and drawing with local-only storage. Pro plan costs $7.99/month with a 7-day free trial, including cloud sync, unlimited sticky notes, PDF export, AI connectors, and API access.
Key features	Modify request and response headers with a focused editor interface Scope rules to specific URLs using browser-supported filter patterns Customize response cookies with Domain, Path, SameSite, Lifetime, Max-Age, and Secure attributes Create up to five local rule profiles for different projects and test setups Import and export profiles as local JSON files between browsers Enable, disable, delete, and annotate rules with comments Support for Chrome, Edge, and Firefox All rules stored locally in browser with no server transmission	Privacy masking with blur tool for sensitive data AI connectors for Claude, ChatGPT, and Grok via MCP server Local-first storage with optional cloud sync on Pro plan Keyboard shortcuts for rapid tool switching Focus mode to toggle annotation visibility Browser PDF highlighting support
What makes it different	Open-source with MIT License and full transparency Rules stored entirely locally with no analytics, tracking, or external servers Lightweight alternative to ModHeader URL scoping prevents rules from affecting unintended websites Simple interface requires no coding knowledge	Designed specifically for academic research with citation-ready PDF exports Built-in MCP server enabling direct AI integration without copy-pasting No account required to start highlighting immediately
Free plan	Not given	Not given
Open source	Not given	Not given
Platforms	Not given	Not given
Public API	Not given	Not given
Community votes	0	0
DR (Domain Rating by Ahrefs)	8 no change since last check	Not checked yet no change since last check
Trust Flow (Majestic)	3	0
Citation Flow (Majestic)	18	6
Referring domains (Majestic)	13	2

4 details filled in for both companies.

More alternatives to Header Override More alternatives to MarklyKit