The Chromium profile and user data directory

Everything personal about your browser lives in one folder: the user data directory. Bookmarks, history, passwords, cookies, extensions, settings, open tabs.

It is entirely separate from the program itself, which is why updating Chromium does not lose your data, and why backing up this one folder backs up your whole browser.

Where it is

Windows

%LOCALAPPDATA%\Chromium\User Data

which is normally C:\Users\<you>\AppData\Local\Chromium\User Data.

macOS

~/Library/Application Support/Chromium

Linux

~/.config/chromium

Forks use their own directory, so Thorium and Supermium each keep a separate folder under the same parent. That is deliberate, and it means installing a fork will not pick up your existing profile.

Never guess: chrome://version shows the exact Profile Path your running browser is using.

Inside it

The directory holds one folder per profile. Default is your first profile; additional ones are Profile 1, Profile 2 and so on. Files shared across profiles, like Local State, sit at the top level.

Within a profile folder, Bookmarks is readable JSON, History and Cookies are SQLite databases, Login Data holds saved passwords, and Extensions contains the extensions themselves.

Backing it up

Close the browser first. Chromium holds SQLite databases open, and copying them mid-write produces a backup that restores into a corrupted profile.

Then copy the whole User Data folder. That is the entire backup, and restoring it is copying it back.

Passwords do not travel. They are encrypted against the OS keychain: DPAPI on Windows tied to your Windows account, Keychain on macOS, and GNOME Keyring or KWallet on Linux. A profile copied to a different machine or user account will restore everything except the passwords. Export those separately from the password manager if you need them to move.

Moving it somewhere else

Use --user-data-dir to point Chromium at a different location:

chrome.exe --user-data-dir="D:\ChromiumProfile"

Copy the existing folder there first if you want your data to come along. This is also how portable builds keep everything in one directory, and how you run several Chromium versions side by side without them fighting.

Fixing a broken profile

Profile corruption shows up as a browser that will not start, starts with everything reset, or crashes on a specific action.

First, test whether it is the profile at all. Start with a temporary one:

chrome.exe --user-data-dir="C:\Temp\ChromiumTest"

If the problem disappears, it is the profile. If it persists, it is the build or the system.

Then repair rather than delete. Close the browser, rename Default to Default.old, and start Chromium so it creates a fresh profile. You can then copy individual pieces back: Bookmarks first, then Login Data, testing after each. Recovering the parts that matter usually works, and it beats starting over.

Bookmarks.bak sits next to Bookmarks and holds the previous version, which is often exactly what you need after bookmarks vanish.

Size

A long-lived profile reaches several gigabytes, mostly cache. The cache is safe to delete with the browser closed, and Chromium will rebuild it. Service Worker and IndexedDB can also be large, but those hold real site data such as offline content and logged-in state, so clearing them logs you out of things.

Related guides

• Chromium command-line flags
• Chromium internal pages