How do I add command-line flags to Chromium on Windows?

Right-click the shortcut, open Properties, and append the flag to the end of the Target field after the closing quotation mark.

What does --user-data-dir do?

It tells Chromium where to store the entire profile, including bookmarks, extensions and history. It is how you run portable builds self-contained and run multiple Chromium versions side by side.

Is --no-sandbox safe to use?

No. It disables the process sandbox, which is the main barrier preventing a compromised web page from reaching the rest of your system. It should never be used for normal browsing.

Chromium command-line flags

Chromium takes a large number of command-line switches. Most exist for developers and build bots, but a handful genuinely solve problems, and a few are actively dangerous.

Setting them

Windows. Right-click your Chromium shortcut, choose Properties, and append the flag to the Target field after the closing quote:

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

macOS. From Terminal:

/Applications/Chromium.app/Contents/MacOS/Chromium --user-data-dir=/tmp/test

Linux. Either run it from a terminal, or edit the .desktop file's Exec= line. For packaged builds, ~/.config/chromium-flags.conf is read by many distribution packages, one flag per line.

The ones worth knowing

--user-data-dir=PATH is the most useful flag in the list. It puts the whole profile somewhere you choose, which is how you run portable builds self-contained, keep several versions side by side, and create a genuinely separate throwaway profile.

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

--incognito starts directly in a private window.

--app=https://example.com opens a site as a bare window with no tabs, address bar or interface. The simplest way to make a web application feel like a desktop one.

--proxy-server="socks5://127.0.0.1:1080" routes through a proxy without touching system settings.

--disable-extensions starts with extensions off, the fastest way to find out whether an extension is causing a problem.

--enable-features=X and --disable-features=X toggle features by name, including some that have no entry in chrome://flags.

--force-dark-mode turns on Chromium's automatic dark rendering for pages that lack their own.

--disable-gpu falls back to software rendering. Worth trying when you get visual corruption or blank pages on a machine with awkward graphics drivers.

Flags you should not use

--no-sandbox disables the process sandbox. The sandbox is the single most important security boundary in the browser: it is what stops a compromised web page reaching the rest of your machine. Guides suggest this flag to work around startup problems, and following that advice turns an ordinary browser exploit into a full compromise of your account. Fix the underlying problem instead.

--disable-web-security turns off the same-origin policy. It exists for local development against an API and nothing else. Never browse with it.

--ignore-certificate-errors makes HTTPS meaningless by accepting any certificate, valid or forged.

--allow-running-insecure-content re-enables mixed content that browsers block for good reason.

The pattern is worth internalising: if a flag's name describes switching off a protection, the protection is almost certainly the thing standing between you and a bad day.

chrome://flags

chrome://flags is a separate mechanism: experimental features with a UI, stored in your profile and persisting across restarts.

They are experiments. They ship broken, they get removed without notice, and a flag that solved something in one version may not exist in the next. If the browser starts misbehaving after you have been in there, Reset all at the top of the page is the first thing to try.

Seeing what is already set

chrome://version lists the full command line the browser is running with, including flags inherited from a shortcut or a config file you have forgotten about. Always check there first when behaviour makes no sense.