Arc
Arc Browser
Overview
Arc is a Chromium-based browser for macOS from The Browser Company. Because it is built on Chromium, its core browsing artifacts (history, cookies, saved passwords, bookmarks) use the same on-disk formats as Google Chrome and can be analysed with the same techniques and tools.
Arc also adds its own organisational layer. Spaces group tabs by project or identity, the sidebar holds pinned tabs, folders, and the short-lived "Today" tabs, and Boosts let a user inject their own CSS and JavaScript into websites. Arc does not store any of this in Chromium's databases. It writes separate JSON files and directories that generic Chromium tooling ignores. These artifacts often show how a user organised their work, not just which sites they visited.
File Locations
| Location | Contents |
|---|---|
~/Library/Application Support/Arc/User Data/ | Chromium profile tree (Local State, Default/, Profile N/) |
~/Library/Application Support/Arc/StorableSidebar.json | Spaces, pinned and Today tabs, folders, Favorites |
~/Library/Application Support/Arc/StorableSidebar.<timestamp>.json | Timestamped backups of the sidebar file |
~/Library/Application Support/Arc/boosts/ | One directory per Boost |
~/Library/Preferences/company.thebrowser.Browser.plist | Application preferences |
/Applications/Arc.app | Application bundle (bundle ID company.thebrowser.Browser) |
Profile Structure
Arc uses the standard Chromium profile layout under User Data/. The first profile is Default/ and additional profiles are Profile 1/, Profile 2/, and so on. Local State maps each directory to its display name in profile.info_cache.
In Arc, every Space belongs to exactly one profile, so switching Space can switch the profile behind it. The sidebar file records this link (see Spaces), which lets you tie a Space such as "Work" to the Profile 1 history and cookie databases.
Artifact Summary
| Artifact | File | Format | Forensic Value |
|---|---|---|---|
| History | User Data/{Profile}/History | SQLite (Chromium) | Visits, downloads, search terms |
| Cookies | User Data/{Profile}/Cookies | SQLite (Chromium) | Sessions and tracking (values encrypted) |
| Spaces | StorableSidebar.json | JSON (Swift Codable) | Workspaces, their profiles and icons |
| Sidebar Items | StorableSidebar.json | JSON (Swift Codable) | Pinned, Today, and Favorite tabs; folders |
| Boosts | boosts/<id>/ | Unpacked extension | User-injected CSS/JS per site |
| Saved Passwords | User Data/{Profile}/Login Data | SQLite (Chromium) | Credential metadata, see Chrome Saved Passwords |
| Bookmarks | User Data/{Profile}/Bookmarks | JSON (Chromium) | See Chrome Bookmarks |
| Preferences | company.thebrowser.Browser.plist | Property list | Application settings |
Arc's sidebar is not in Bookmarks
Arc's pinned tabs, folders, and Favorites live in StorableSidebar.json, not in the Chromium Bookmarks file. Arc's own bookmark export reflects only the Chromium file, so collecting Bookmarks alone misses most of what a user saved in Arc.
Timestamps
Arc uses two timestamp encodings, depending on where the data comes from:
| Source | Encoding | Convert to Unix seconds |
|---|---|---|
| Chromium databases (History, Cookies, Login Data) | WebKit: microseconds since 1601-01-01 UTC | webkit / 1000000 - 11644473600 |
Arc JSON (StorableSidebar.json) | Mac absolute time: seconds (float) since 2001-01-01 UTC | mac + 978307200 |
Encryption
Cookie values and saved passwords are encrypted the same way Chrome encrypts them on macOS. Arc uses AES-128-CBC with a key derived from a secret stored in the user's login Keychain. Chromium browsers name that Keychain item <Browser> Safe Storage. Check the exact item name in the subject's keychain rather than assuming it. macfor records encrypted values and their metadata but does not decrypt them.
Collection Order
macfor (browser.arc, Pro) collects per profile, then per user:
- History (including downloads and search terms)
- Cookies
- Login Data
- Bookmarks
- Spaces (
StorableSidebar*.json, including backups) - Sidebar items
- Boosts
- Preferences
- Raw files (opt-in)
Tool Support
| Tool | Support |
|---|---|
| macfor | All artifacts above, including Spaces, sidebar items, and Boosts |
| Hindsight | Chromium History/Cookies (point it at Arc's User Data/ profile) |
| DB Browser for SQLite | Manual inspection of the Chromium databases |
jq | Manual inspection of StorableSidebar.json |