What is l.facebook.com in my analytics?

Why you see the shim, not the post

When you click an outside link on Facebook, it goes through Facebook’s link shim first. In a 2012 post, Facebook’s engineers describe two jobs for it: check every link on the page for spam and malware (a suspicious one gets a warning page), and restrict the referrer. Their words: they still want the site you land on to know the traffic is from Facebook, but not to read the full address you were on, because that would show where on Facebook you were.

They do it with a meta referrer, an instruction on the page that tells the browser to send less than the full address. So your analytics gets a Facebook hostname and nothing after it.

The different hostnames

You will see more than one:

• l.facebook.com: the hostname outgoing clicks are seen passing through. Meta’s post doesn’t name it, but it is where the shim’s links point.
• lm.facebook.com: another Facebook hostname seen for the same kind of click.
• m.facebook.com and facebook.com: Facebook’s own pages, when the click did not go through the shim host.

They all mean Facebook. Add them together when you read your numbers; splitting them tells you very little.

What it hides

Everything that would tell you which effort worked. A post on your own page, a comment in a group, a friend sharing your link in a message and a link in someone else’s post all arrive as the same hostname. If you post in several groups, you cannot tell them apart from the referrer.

How to see which post it was

Tag the link before you post it. Tags are part of the address, so they survive the shim:

https://example.com/?utm_source=facebook&utm_medium=social&utm_campaign=founders-group-sept

Use one utm_campaign per post or group, and keep a list of the names you have used. When other people share your link untagged, those visits still show up as plain Facebook, which is fine: that is word of mouth.

Where it goes in your reports

Most tools that know these hostnames put them under social. A tool that doesn’t will list l.facebook.com as a separate website under referrals. If you see it there, read it as Facebook.

With Nordva Launch

Launch counts l.facebook.com, lm.facebook.com, m.facebook.com and facebook.com as social, and the Facebook app on Android too. A tagged link keeps its utm_campaign, so each post shows as its own row in your analytics. A UTM tag that names a channel (a medium such as email or social, or a known source) wins over the referrer when the two disagree. Facebook adds fbclid to ordinary links as well as ads, so Launch doesn’t treat it as a sign of an ad: tag your ads with a utm_medium such as cpc or paid and they count as paid.