A small macOS browser built on Chromium, with a native Swift/AppKit interface and a built-in agent panel that can drive the browser.

• Chromium engine, native shell. Pages render with Chromium through CEF; the window, tabs and menus are AppKit.
• Tabs and session restore. Tabs along the top or in a sidebar, with a context menu; open tabs and recently closed tabs survive restarts and crashes, and the start page brings the closed ones back.
• The usual browser things. Find in page, zoom, print, a link's address under the mouse, pages going full screen, Chromium's developer tools and view source.
• Downloads. Files go to ~/Downloads, with progress in the toolbar.
• Import from Chrome. Cookies, saved passwords, history, extensions, search engine and homepage.
• Chrome extensions. Add unpacked folders or CRX files, or bring Chrome's over. Content scripts, background workers and popups run; Chrome's tab and window APIs don't see Tiller's tabs.
• Profiles. Each profile has its own site data, history, passwords, settings and chats, and runs as its own app instance.
• Agent panel. Chat with Qoder CLI, Claude Code or Codex in a side panel that controls the browser, and call skills with /, from your own folders or a skill library each agent shares. Prompts can also run on a schedule, skills included, set up in Settings or by asking the agent.
• Browser tools. A stdio MCP server and the tiller command-line tool expose the same tools to external agents and scripts.

• macOS with the Swift toolchain (Xcode Command Line Tools)
• Rust, installed through rustup
• Ninja
• CEF 154, matching the cef version pinned in Cargo.toml

Install the toolchain and download CEF once:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
brew install ninja
git clone https://github.com/tauri-apps/cef-rs && cd cef-rs
git checkout cef-v154.2.0+154.0.28
cargo run -p export-cef-dir -- --force $HOME/.local/share/cef

The build reads CEF from $CEF_PATH, which defaults to ~/.local/share/cef. Update the download whenever the pinned cef version changes.

That download can't play H.264 video or AAC audio, which X, most news sites and most MP4 files use, because the stock CEF builds leave those patent-encumbered codecs out. To play them, put a CEF framework built with proprietary_codecs=true in ~/.local/share/cef-codecs. The build uses the framework there when present, and the headers from $CEF_PATH either way. aiexkwan/aurix-cef publishes such a build for the same Chromium as the pinned CEF, made by a third party and unsigned, so check that it's one you're willing to run:

brew install zstd
mkdir -p ~/.local/share/cef-codecs
curl -L https://github.com/aiexkwan/aurix-cef/releases/download/cef-154.0.26-codecs/cef-154.0.26-macosarm64-slim.tar.zst \
  | tar --use-compress-program=unzstd -x -C ~/.local/share/cef-codecs

Or build CEF yourself with proprietary_codecs=true ffmpeg_branding=Chrome and copy its framework there. Set CEF_FRAMEWORK_DIR to use a framework from another folder. The framework's version must share the pinned CEF's major version and API hash; the script prints the one it picked.

scripts/bundle.sh                                       # release build; pass `debug` for a debug build
open build/Tiller.app
open build/Tiller.app --args -url https://example.com   # open a page at launch

The script builds the Rust crates and the Swift app, then assembles an ad-hoc signed build/Tiller.app. To keep the bundle small, it includes only the English and Chinese Chromium locales and omits SwiftShader, so there is no software rendering fallback when the GPU is unavailable.

Agents in the panel use Tiller's browser tools automatically. External agents and scripts can use the MCP server at build/Tiller.app/Contents/MacOS/tiller_mcp, or the tiller command-line tool, installed from Tiller > Install Command Line Tool…:

tiller new example.com      # open a tab and wait for the load
tiller read                 # page text with numbered links, buttons and fields
tiller click 3
tiller type 5 "hello" --submit

See Browser tools for every tool, command and option.

MIT