Give your browser AI wings
OpenSider is a browser extension that drives local Agents (Claude Code, Codex, OpenCode, Cursor and other local Agent CLIs that speak ACP) from within your browser for web information gathering, web automation, and more.
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Collaborate with Agents in the browser
Chat with your local Agent directly in the browser side panel, without opening command line or terminal tools. -
Reuse your real browser state
Your identity on a site (login state) and any form input you have already filled in are reused, so you never have to reconstruct the scene. -
Automatic web page context
No need to tell the Agent which page you are viewing — the Agent automatically gets the page information loaded in your browser and can operate on it. -
Web automation
Navigation, reading, clicking, form filling, screenshots and more are injected into the Agent as tools, and the automation plays out live on the page (simulated mouse clicks, keyboard input, …). -
Collaborate in place
Wherever you are, the Agent works with the information on that page. You can also pick a page element to ask about it. -
Switch Agents and models freely
Switch Agent/model with one click, and even within the same session you can use different Agents — no terminal tooling to hold you back. -
Data persistence
All session data is stored locally, so it won't be lost when the app is updated or reinstalled.
What it shows: chat with the Agent to distill web page information into a news digest (an HTML file), which is then opened in the browser.
opensider.mp4
This extension is for Chromium-based browsers such as Chrome / Edge / Brave. Before installing, make sure you already have a running Agent CLI program on your machine.
One-step install: paste the prompt below into the local AI Agent you already use (Claude Code, Codex, OpenCode, Cursor, …). It will prepare your local environment and walk you through installing the browser extension.
Install the OpenSider browser extension for me.
Read https://raw.githubusercontent.com/parksben/opensider/main/skills/opensider/SKILL.md and follow its install flow.
One-step update: when the side panel tells you a new version is available, copy the prompt below to your local Agent and let it guide you through the update.
Update the OpenSider browser extension for me.
Read https://raw.githubusercontent.com/parksben/opensider/main/skills/opensider/SKILL.md and follow its update flow.
One-step uninstall: one prompt is all it takes, and you choose whether to keep or remove your local data.
Uninstall the OpenSider browser extension for me.
Read https://raw.githubusercontent.com/parksben/opensider/main/skills/opensider/SKILL.md and follow its removal flow.
OpenSider never uploads your configuration or chats to any server: all sessions and Agent artifacts live on this machine under ~/.opensider, and they stay usable after uninstalling or reinstalling the extension.
| File / folder | What it holds |
|---|---|
~/.opensider/workspace/ |
The Agent's working directory: every tab and every session works in this same folder |
~/.opensider/workspace/browser/ |
Scratch files produced during a session, such as the current page snapshot, interactive controls, page commands and results, screenshots |
~/.opensider/workspace/outputs/ |
Artifacts the Agent produces during a session (tables, documents, code, …) |
~/.opensider/ui-state.json |
Session list, chat history and preferences |
~/.opensider/runtime/ |
The local bridge binary, plus the Claude Code / Codex ACP adapters |
~/.opensider/host.log |
Bridge log — the Agent can use it to debug problems. Rotated by size and by date, keeping the last few files as host.log.<timestamp> |
The extension folder you picked at install (suggested ~/OpenSider/) |
The folder the browser actually loads — do not move or delete it, or the extension breaks |
On Windows these live under %USERPROFILE%\.opensider and %USERPROFILE%\OpenSider.
OpenSider is itself an Agent client: its local bridge starts an Agent process and uses ACP to carry sessions, streaming responses, tool calls, and permission requests. A compatible Agent therefore needs a CLI that speaks ACP directly or through an adapter.
Desktop apps such as Claude and Codex keep their runtime behind their own UI and do not expose a stable ACP process endpoint for OpenSider to start and control. Automating their windows would be brittle and could not preserve the full protocol behavior, so the desktop apps themselves are not supported. Their corresponding CLIs can still be used when they provide ACP or have a compatible adapter.
To connect a supported Agent product:
- Visit the product's official website and find its official Agent CLI.
- Follow the official instructions to install the CLI and sign in.
- Run the OpenSider installation prompt above again. OpenSider will detect the CLI and configure any available ACP integration.
For example:
- Claude Code: install and sign in to Claude Code CLI, then run the OpenSider installation prompt again.
- Codex: install and sign in to Codex CLI, then run the OpenSider installation prompt again.
If the product has no Agent CLI, ACP interface, or compatible adapter, OpenSider cannot connect to it yet.
Having the CLI installed is not enough by itself: it may lack an ACP entry point or adapter, be outside the local bridge's PATH, or have an incomplete setup. Send this prompt to the local Agent you already use:
Help me diagnose and fix an installed Agent CLI that does not appear in the OpenSider side panel.
First read https://raw.githubusercontent.com/parksben/opensider/main/skills/opensider/SKILL.md, then follow its doctor and repair flow to check the CLI's ACP entry point, launch command, PATH, and required adapter. Fix what can be fixed and verify that it appears in the side panel; if it has no ACP interface or usable adapter, say so clearly.