A community-built extension that lets you call Nous Research’s open-source Hermes Agent from a browser side panel. Developed by Jon Komet (GitHub: abundantbeing), it supports Chromium-based browsers such as Chrome, Edge, and Brave, as well as Firefox. Connect it to a Hermes API running on your own machine and you can use the models, tools, skills, sessions, memory, and MCP servers you have already configured, directly in the browser. Because the current tab and any selected text can be passed straight through as context, tasks like summarizing an article or drafting a reply can be finished without leaving the page. The first alpha was published on June 24, 2026, and v0.3.0 on August 22, 2026 expanded it to approval-gated browser control. It is released under the MIT license.
Key Features
- Pass page context straight from the side panel: Hand the body text of the current tab, a selection, or a list of open tabs to Hermes. Page content is explicitly wrapped as untrusted context before it is sent, and receipts let you check what Hermes actually saw
- Three connection modes: A local gateway (default
http://127.0.0.1:8642), Hermes Cloud through a signed-in dashboard tab, or your own remote gateway (HTTPS plus an API key, or access over a VPN or Tailscale) - Quick commands: Slash commands such as
/summarize,/explain,/rewrite,/tabs, and/action-items - Hermes Assist (inline drafting): Added in v0.2.0, it recognizes 31 writing environments including Gmail, GitHub, and Slack, and shows a compact drafting panel next to the composer
- Hermes Web (full-page workspace): Separate from the side panel, a full-screen workspace that gathers conversation history, model controls, and media generation
- Approval-gated browser control: Since v0.3.0, with an explicit per-tab lease, the extension can take snapshots, click, type, and navigate. Consequential actions pass through an approval gate before they run
- Appearance and input options: Nine themes with Light/Dark/System modes, plus voice dictation via Hermes audio transcription or the browser’s own fallback
Pricing
| Plan | Price | What you get |
|---|---|---|
| The extension itself | $0 (MIT license) | Every feature. Get the source from GitHub and build it yourself |
| Hermes Agent (the backend) | Separate | Running the open-source version locally adds no cost on the extension side. Hermes Cloud or external model APIs are billed by their own providers |
Pricing is current as of August 2026. Check the official repository for the latest information.
Pros & Cons
✅ Pros
- The extension is free and open source, so you can read the code and confirm how it behaves
- If you run Hermes locally, page content can be processed without sending it to an outside SaaS
- Models, skills, and MCP servers already configured in Hermes carry over, so there is no separate setup for the browser
- Browser control is opt-in and puts an approval step before actions run
- Development is active: the feature set grew substantially in the two months after the June 2026 release
⚠️ Cons
- It is not on the Chrome Web Store. You need to clone the repository, run
npm install && npm run build, and load it in developer mode (only Firefox gets a signed package through Releases) - Hermes Agent has to be set up first, which is a heavy prerequisite if you only want to try an AI chat panel
- It is officially a public alpha, so specifications may change and bugs are possible
- The Hermes Cloud connection mode cannot pass page text or attachments, and is limited to chat
- There is currently almost no documentation or commentary in Japanese
Comparison with Similar Services
| Criteria | Hermes Browser Extension | Sider | Monica | Built-in browser AI assistants |
|---|---|---|---|---|
| Type | Community-built extension | Commercial service | Commercial service | Built into the browser |
| Backend | Your own Hermes Agent (local / self-hosted / cloud) | The vendor’s servers | The vendor’s servers | The vendor’s servers |
| License | MIT (source published) | Proprietary | Proprietary | Proprietary |
| Price | Free (backend costs are separate) | Free tier plus paid plans | Free tier plus paid plans | Bundled with the browser |
| Installation | Build and load it yourself | Add from the store | Add from the store | Preinstalled |
| Best for | People who want to own their stack | People who want to start immediately | People who want to start immediately | People who want no extra setup |
Who Is It For
- People already running Hermes Agent locally who want the same setup available in the browser
- People who would rather not send the pages they browse to an outside service, or who want to choose the destination themselves
- People who want to bring MCP servers and their own skills into browser work
- People who want to inspect an extension’s code before trusting it
- Anyone who wants help with reading and writing in the browser, such as summarizing articles or drafting emails
Summary
Hermes Browser Extension connects the Hermes Agent running on your own machine directly to your browser work. Compared with commercial AI side panels, setup takes more effort, but the clear differences are that you control the backend and the configuration, and that the MIT license lets you verify what the code does. Since it is still a public alpha, check the approval gates and the scope of context handoff yourself before folding it into production work.