Marhiv GitHub

Free & open source

Make the AI chatbots
you already use your own.

Marhiv is a Chromium extension that lets you layer themes, shortcuts, and automations onto your AI chatbots — starting with Claude, and coming to ChatGPT and Gemini. Use curated plugins, or write your own when you want full control.

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Free & Apache-2.0 · Chromium (Chrome & Edge) · No account required

Why Marhiv

AI chat interfaces are powerful — but one-size-fits-all.

Marhiv is the customization layer that sits on top of the tools you already live in.

Make it yours

Themes, layout tweaks, and quality-of-life fixes for the AI sites you live in — recolor the whole page or reshape a single screen.

Curated, not chaotic

A vetted catalog of themes and tools bundled right into the extension — browse and toggle each from the on-page panel. Safe by default; the set grows with every update.

An escape hatch for power users

Write or paste your own site-matched scripts when no plugin exists — full control when you want it.

Built to span your tools

One place to manage enhancements across your AI chatbots, instead of one bookmarklet per site. Claude works today; adding the next site is a small, declarative change.

The hybrid model

Two ways to enhance a page.

Both run through the same content-script host on supported AI sites, sharing one documented Enhancement API — so anything a plugin can do, a userscript can too.

Plugins

curated & bundled

Curated, first-party enhancements that ship bundled inside the extension. Each declares the AI sites it targets and what it does. Browse, toggle, and configure them from the on-page panel — new ones arrive with each Chrome Web Store update.

  • Enable / disable live, persisted across tabs
  • Reach the host page through a typed Enhancement API — never raw selectors
  • Contribute their own settings pages at runtime

Userscripts

your own escape hatch

Sandboxed, user-authored scripts matched to specific sites, for the cases curated plugins do not cover. They run through the same shared API as plugins, so anything a plugin can do, a userscript can too.

  • Site-matched by URL pattern
  • Run through the shared, documented Enhancement API
  • Treated as untrusted — no raw page or extension access

Built in, today

Curated plugins, ready to toggle.

Every plugin is bundled right into the extension — enable or disable each live from the on-page panel. The catalog grows with each Chrome Web Store update, and anyone can add one with a pull request.

Theme

Marhiv Theme

Recolors the host AI site in the Marhiv alpenglow palette.

Themes

Editor theme pack

Beloved editor palettes for your chat UI — Tokyo Night, Catppuccin Mocha, Rosé Pine, Gruvbox, One Dark, Dracula, Nord, Monokai, Everforest, Solarized.

Workflow

Claude Code enhancer

Adds a native item under "New session" on claude.ai/code — a worked example of the Slots engine targeting one route.

Developer

Dev tools

A live route readout and debug-state export, plus a network recorder — a plugin that adds its own UI and reads app state.

Cross-tool

Runs on Claude today — more on the way.

Marhiv supports Claude right now. ChatGPT and Gemini are next: the plugin model is built so adding a new site is a small, declarative change.

Claude Supported today
ChatGPT Coming soon
Gemini Coming soon

For builders

An architecture made to be extended.

Plugins never touch raw selectors. They go through abstractions designed so a host site’s redesign is a one-file fix — not a rewrite.

01

Enhancement API

The shared contract both plugins and userscripts use to read and modify the chat UI, register commands, add UI, and persist settings. The keystone abstraction.

02

Slots engine

Plugins map a semantic slot name to live DOM through per-route resolvers, with presence tracking that survives the host SPA re-rendering. A host redesign is a one-file fix.

03

Per-site router

Matches the URL against a site’s routes and drives enter/leave behavior as the SPA navigates, each scoped to an AbortSignal for clean teardown.

04

Shadow-root UI

The settings panel renders into a shadow root, fully isolated from the host page’s CSS — so Marhiv never fights the site it enhances.

Built to be extended

Like something? Want to extend something?
Submit a PR.

Marhiv is open source and built to be edited with Claude Code. The repo ships a dedicated set of skills that scaffold the common extension points — so you, or your agent, go from idea to pull request without spelunking the internals.

Browse the source Fork & open a PR
  • /plugin-create Scaffold a new built-in plugin, wired into the registry.
  • /panel-page-create Add a settings page to the on-page panel.
  • /host-element-access Reach a host element safely through the Slots engine.
  • /state-management Add persisted or ephemeral state the right way.

Reach the summit of your AI tools.

Clone it, load the unpacked extension, and shape the AI chatbots you use every day. Contributions and ideas welcome.

Star it on GitHub Install guide