Want to check if a particular internet handle you encountered online (or created yourself) is being used on any other social networks or websites? Sherlock is a free command line application that scans around 400 social networks and finds accounts that match whatever username you type in.

Using this service couldn't be simpler: Just open it up and type "sherlock" followed by the username your want to search for. The program will check every site it can access and tell you where accounts matching your username exist, complete with a link to the relevant profile page. This is useful in two ways: finding people across multiple websites, and checking whether a username you're thinking of using is already taken on other sites.

Find a specific user name anywhere it's registered

The first of those use cases isn't foolproof, of course. For one thing, some people use different handles on different websites. For another, accounts with the same name on different websites aren't necessarily going to belong to the same person or brand (most of the accounts in the screenshot at the top of this post, for example, do not belong to Lifehacker). Still, just knowing where other accounts with the same handle exist is a great starting point if you're curious what other sites the person you're searching for uses regularly.

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Check if your user name is taken almost anywhere

The second scenario, checking whether a handle you're thinking of using is broadly available on the web, is possibly much more useful. Whether you're thinking of starting a company or just toying around with a new internet handle, it's good to know whether anyone else is already using your chosen moniker.

How to set up Sherlock on macOS, Linux, and Windows

Sherlock is useful, yes, but a little bit tricky to set up.

On a Mac, the simplest way to tackle it is to install the service using Homebrew, which makes installing and updating Mac apps much easier. After setting up Homebrew, you'll only need to open that app and type "brew install sherlock" to install. Things are easier if you're a Linux user: Sherlock is likely already offered by your package manager.

Things are much harder on Windows, sadly. On that system, I recommended you set up pipx for installation. This is a sort of package manager for Python scripts. The process is probably not going to be straightforward if you're not already comfortable with the command line, but as an overview, you'll need to install Python, then use pip to install pipx, then use pipx to install Sherlock. Yes, that's a lot setup to use one simple tool. But once everything is set up, Sherlock couldn't be easier to use—and it just might be worth the effort.