# Serein: the site as plain text

Serein is a free, native macOS browser for coding agents. It is an agentic harness for the browser: it has no agent of its own. It runs the agent command-line tools that are already on a person's Mac in a real browser, under that person's control. Agents work in visible tabs with their own cookies. They get only the access that the user grants, and the user can take that access back.

Serein works with Claude Code, Codex, Cursor Agent, OpenCode, Command Code, Grok, Hermes Agent, and Pi or Oh My Pi, when they are installed.

This file says the same things as https://serein.pro/ in plain text. The index of all plain-text pages is https://serein.pro/llms.txt.

## What it does

- **One box for everything.** The omnibox ranks addresses, searches, tasks, open tabs, history and saved pages. `⌘T` opens a tab and `⌘L` goes to the omnibox. A `/` at the start makes the entry a task.
- **One composer for tasks.** `⌘E` opens it. Serein routes each request to an answer, research, the current page, the library, the Mac ("Anywhere") or a project, and shows the reason. The user can choose the destination.
- **Questions about a page.** `⌥⌘E` opens the task panel beside the page with the page and the selection attached. `⇧⌘E` lets the user point at up to three elements. The user sees exactly what is sent.
- **Web tasks in visible tabs.** A web task runs in agent tabs that have their own cookie store. The user can take a tab over at any moment. A result shows the answer and the steps.
- **Up to three tasks at the same time.** Each task has its own process group and its own permissions.
- **Follow-ups keep their context.** A follow-up resumes the native Claude Code or Codex session.
- **Every file edit can be reviewed.** Serein makes a snapshot of each turn's changes in a private Git ref. The user reads the diff and can undo or redo the turn. Each edit needs approval: allow once, always allow in this project, or deny.
- **A full browser.** Vertical or horizontal tabs, tab groups, a comparison table made from up to six tabs, downloads with resume, permissions for each site, content blocking, find in page, zoom for each site, and export to PDF.
- **Journal.** The day on a timeline. The user finds a visit by a description of it, with an index that stays on the Mac.
- **Passwords.** Kept in the Mac's Keychain, filled only on the exact site, and never submitted by Serein.
- **Hold to talk.** The user holds `fn` to dictate into a page, the omnibox or the composer. Apple Speech does the transcription on the Mac.

## Control model

- Every task can read pages. Clicks and typing, the user's sign-ins, project edits and Mac actions are off until the user grants them.
- Stop takes a task's browser access away at once.
- On a password, payment or verification-code page, the task gives the tab back to the user. Agents never get the contents of password or payment fields.
- Agent tabs keep their own cookies. "Use my sign-ins" is a grant for one task, and the user can take it back.
- Private windows never reach an agent.
- There are no API keys. Each agent tool runs with its own sign-in. Serein never types, stores or reads a credential of a provider.

The details are in https://serein.pro/llms/permissions.md.

## Install

1. Serein needs macOS 14 or later. It is free. The file https://serein.pro/release.json gives the version, the size, the processor type (`arch`) and the SHA-256 of the current build.
2. Download the disk image from https://serein.pro/#download.
3. Open the disk image and move Serein to the Applications folder.
4. Open Serein. A short setup opens the first time. It finds the agent tools on the Mac and signs in through each tool itself. Every step can be skipped.
5. To let agents act in other Mac apps, the setup asks for Accessibility, Screen Recording and Automation, one at a time. This step is optional. Without it, agents stay in the browser.

## Privacy

History, the journal, projects and conversations stay on the Mac, in `~/Library/Application Support/Serein`. Serein has no accounts. The app sends no analytics, telemetry or crash reports. The website sets no cookies. Its home page counts visits with Vercel Web Analytics, which also sets none.

When the user gives a task to an agent, Serein passes the task and its context to that agent's command-line tool on the Mac. The tool sends them to its provider under the user's own account. Serein does not get a copy.

Full text: https://serein.pro/privacy and https://serein.pro/security.

## Pages

- Guides: https://serein.pro/llms/claude-code.md, https://serein.pro/llms/codex.md, https://serein.pro/llms/cursor-agent.md
- Permission model: https://serein.pro/llms/permissions.md
- Questions and answers: https://serein.pro/llms/faq.md
- Comparison with other tools: https://serein.pro/llms/compare.md
- Changelog: https://serein.pro/llms/changelog.md
- For people: https://serein.pro/, https://serein.pro/privacy, https://serein.pro/terms, https://serein.pro/security, https://serein.pro/licenses