Circle

A calm, sidebar-first web browser in the spirit of Arc: the arc, completed. Written in Rust on top of Chromium via the Chromium Embedded Framework (cef-rs).

What it does

• Vertical sidebar with back/forward/reload, the address and your tabs; it animates in and out (⌘S)
• Quiet window chrome: an even frame around rounded pages; the macOS traffic lights live in the sidebar. With the sidebar hidden, point at the left edge to peek at it (lights included)
• Favorites — a grid of icons shared by every space
• Spaces — separate sets of pinned and today tabs, each with its own color; switch with the dots, Ctrl+1…9 (macOS) / Alt+1…9, ⌘⌥←/→, or a two-finger swipe on the sidebar
• Pinned tabs that remember their home page; closing one unloads and resets it
• Folders for pinned tabs: collapsible, created from a space's ••• menu or a tab's right-click menu; drag tabs in and out
• Rename tabs: double-click a tab's title (or right-click › Rename…); the page title is used until you do
• Today tabs that archive themselves after 12 idle hours (configurable)
• Command bar (⌘T, ⌘L): search, open URLs, jump to open tabs, reopen recently closed tabs and run commands
• Split view (⌘⇧= or right-click → Open in Split View), side by side or stacked (⌘⇧-, or Open in Split View Below)
• Find in page (⌘F), downloads list, site permission prompts in the sidebar
• Drag tabs between favorites, pinned, today and other spaces; right-click for more
• Developer tools (⌥⌘I, View › Developer, or right-click › Inspect Element), docked right or bottom (drag the edge to resize) or in a separate window
• AI agent control: agents like Claude Code can drive Circle through MCP (see below); off until you allow it
• History (⌘Y / Ctrl+H): searchable, grouped by day, entries removable; also offered in Spotlight. Clear browsing data (⌘⇧⌫) by time range: history, cookies, cache
• Local dev servers stand out: tabs on localhost, *.localhost, 127.x.x.x, [::1] or 0.0.0.0 get a "DEV" badge in the sidebar and address bar (which also shows the port), and on macOS a striped frame in the space's color
• Record the page as a video or a GIF: ⌥⌘R (View › Record Video… or the command bar) shows the recording controls in the sidebar; pick Video or GIF, press Start recording, then Stop to save it to Downloads. Videos are MP4 (AV1; WebM where unavailable), GIFs up to 60 s at ~20 fps
• Bug reports (Help › Report a Bug…, the command bar or Settings): answer a few questions, reproduce the problem while Circle logs navigations, actions, page errors, failed loads and crashes, then get editable GitHub-issue text (addresses trimmed to sites unless you opt in)
• Fap mode 🙈 (⇧⌘N / Ctrl+Shift+N): private browsing in a dark space whose tabs use a memory-only session (no cookies, cache or storage on disk) and leave nothing behind: no history, no recently closed, not saved, no remembered permissions, invisible to AI agents and to other spaces' Spotlight. On macOS the window is hidden from screen sharing and screenshots while it shows. ⇧⌘. ends it at once, closing every private tab
• Automatic updates: Circle checks GitHub Releases every few hours, downloads the new version in the background, verifies it against the release's SHA256SUMS.txt and installs it when you quit (or press Restart in the sidebar). Settings › Updates turns it off. A .deb install in /opt is told about new versions instead
• Light and dark themes, or follow the system; websites get the same prefers-color-scheme
• Settings (⌘, / Ctrl+,, Circle › Settings…, or the command bar): theme, search engine, tab archiving, site permissions, DevTools position, agent access, and a shortcut list
• Downloads panel: the button at the bottom of the sidebar opens a list of downloads and recordings (with progress and Show in folder) and closed tabs
• Sessions persist across restarts; can be set as the system default browser

Keyboard shortcuts use ⌘ on macOS and Ctrl elsewhere.

Shortcut	Action
⌘K	Spotlight: switch tabs, open a site, or search
⌘T / ⌘L	Command bar (new tab / edit address)
⌘W, ⌘⇧T	Close tab, reopen closed tab
⌘S	Toggle sidebar
⌘D	Pin / unpin tab
⌘1…9, Ctrl+Tab, ⌘⌥↑/↓	Switch tabs
⌘⇧=	Toggle split view
⌘F	Find in page
⌘⇧C	Copy URL
⌘[ ⌘], ⌘R	Back, forward, reload
⌘⌥I / F12	Developer tools
⌘⌥U	View page source

AI agents

Circle can be controlled by AI agents through the Model Context Protocol. It is off by default:

1. In Circle, open the command bar (⌘T) and run Allow Agent Control. While an agent is acting, the sidebar shows Agent in control with a Stop button.

2. Register the bundled MCP server with your agent, e.g. Claude Code:

   claude mcp add circle -- /Applications/Circle.app/Contents/MacOS/circle-mcp   # macOS
   claude mcp add circle -- /opt/circle/circle-mcp                               # Linux (.deb)
   

   On Windows it is circle-mcp.exe next to circle.exe.

3. Optionally install the skill that teaches agents how to use it well: cp -r skills/circle-browser ~/.claude/skills/.

Tools: circle_tabs, circle_open, circle_navigate, circle_activate, circle_close, circle_back/forward/reload, circle_read, circle_snapshot (interactive elements with refs), circle_click, circle_type, circle_press, circle_scroll, circle_wait_for, circle_screenshot and circle_eval.

Agents act in your real browser with your logins, so only allow agents you trust. Access ends when you turn it off or quit Circle; the token is regenerated on every launch.

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