Some thought-provoking ideas about how LinkedIn figures out who to suggest to you

This question came up recently in my circle of colleagues about how LinkedIn chooses who to recommend to you for connecting.  The question was prompted when LinkedIn suggested connecting with someone the person had only had email connection with and about an Airbnb opportunity.  So how did LinkedIn know to make that recommendation?  No one had connections in common, no looking at each other’s profiles, no other apparent interaction…

Check out this account by someone familiar with algorithms for preferences (not someone from LinkedIn, but some very good guesses).

Roughly, LinkedIn connections algorithm may work something like this.

Anything you do on LinkedIn’s site is tracked.

You look at Joe Smith’s profile (regardless of whether you try to connect to him), you get a “10 points” in the score box for “Jane knows Joe Smith” you also get “1 point” in the score box for “Jane knows someone with the name Joe Smith”

You upload your contact list to LinkedIn, you get 100 points for each person in the list.

These are first order estimates – they depend on your actions on the site.


Ok, now 2nd order LinkedIn suggestion effects:

When you looked at Joe Smith’s profile, you got points.  Joe – through no action of his own – also got points – let’s say 5 points for “Joe Smith knows Jane Doe”  and 0.5 points for “Joe Smith knows someone named Jane Doe”.

Oh, both Joe and Jane live in Los Gatos CA — give them each a point in their buckets.

Hey, they both link to Toastmasters, or mention Toastmasters on their profile, another point.

Wow – they both worked at XYZ in 2001, and 2002 – give them a point for each year.

At some point, the “guess” that “Jane Doe knows Joe Smith” has enough points – so they float it by you in the “People you might know” column.

If you click it – more points.  You don’t click it – remove a point — you continue not click it, points go down, and it disappears from the list.

Now things start to get interesting – now we can throw some “Machine Learning” into it.

You can imagine some processor thinking – hey, when we show Jane a Toastmaster, she clicks on it 30% of the time, vs only 12% of the time for non-Toastmasters.  She must be really active in this Toastmaster thing – so instead of giving her a point for “toastmasters” in common with someone, let’s use two points.

Oh, and she never clicks on “XYZ people” – lets only use 1/2 point there.

Humm, and she never seems to click on “guesses” with less than 30 points, so instead of 25 points (which is good for lots of people) we’ll use 30 for Jane.


Now let’s add 3rd order effects for LinkedIn suggestions.

Dave is now a member of Linked In.

Dave knows Joe Smith.  Dave knows Jane.   That’s support for the idea of “Jane knows Joe Smith” – let’s give that idea a point.

Oh!  Jackpot!  Dave uploaded his contact list!  Joe Smith is there, Jane is there – they gotta know each other !!

Let’s improve the algorithm with some clustering effects:

Jane knows Dave, Louis, Alan, and Helen.

Joe Smith knows Dave, Alan, and Helen.

Alan knows Jane, Louis, Helen, and Dave

That’s a pretty good cluster — 1 point for the idea that Jane knows Joe.

And, hey, while I’m at it, 1 point for Louis knows Joe.


Making your head spin yet?  No?  Ok, 4th order effects:

Jane knows Helen.  Helen knows Mark.  Mark went to the same high school as Joe.

Another point for Jane knows Joe.

Hey, Mark just edited his profile, he went to both high school and college with Joe !

That’s another point for Jane knows Joe.


More history effects for LinkedIn suggestions:

Remember I uploaded my contact list, 10 paragraphs ago?

Well, Luddite Louis SC was in that list — but wasn’t a member of LinkedIn.  But he just joined!   Yummy!  Since Dave knows Louis, let’s ask Louis if he knows Dave (this is how they can make good guesses immediately after you join the site).  Oh, and next time Dave shows up at the site, remember to tell him that Louis is now a member!


Ok, 5th order effects – take 4th order, and add another person to the chain.

Decrease the point scores, ‘cus it’s getting to be real fuzzy around here.

Humm, Jane let us know her Twitter handle.   We buy the data feed from Twitter, let’s see who she mentions in her tweets – those are good clues about who she knows.

(While some people might consider this spying — it’s all disclosed as part of the terms in conditions in the click-through license that she agreed to when signing up for LinkedIn and Twitter – so it must be OK, right ?  Geez, it’s right there on page 23 of 543, that’s practically on the cover sheet!)


Oh, WOW, you mean I can just fetch a page from Facebook and get names of people Jane knows?

Hey, Jane just sent a contact request to Peter (via the LinkedIn mail interface) – and she mentioned the name Joe Smith!   Wow, she’s practically MARRIED to Joe!  I gotta ask her if she knows him!


Let’s take the person in question, who wondered “How did LinkedIn know that I exchanged emails with the Airbnb person?”   Ok, so I offer my place on AirBnB – and Random Jane contacts me about it?  What’s the first thing I do?  Check Random Jane’s reputation – likely on LinkedIn.  LinkedIn will remember “Dave was interested in Random Jane” and conclude “Maybe Random Jane knows Dave”.

I doubt LinkedIn is spying on your email — except for email you send USING LinkedIn’s site.

However, if you give LinkedIn permission to access your contact list on Google, Yahoo, Hotmail, etc, they likely keep a copy of your password – and may actually fetch it again a month later.  (And, almost certainly, this would be spelled out in the Terms of Service that no one reads).

And even if you told Facebook “don’t share my info with LinkedIn” — bugs show up all the time, particularly with Facebook privacy controls – and once the info is copied, it’s “in the wild” and will be preserved by someone.

So that’s rough account of how LinkedIn finds people to recommend to you for connecting… What did you learn from this?  I, for one, am wondering how all the rest of my social media worlds are connected – raises a lot of interesting questions…

UPDATE: June 13, 2014  LinkedIn has lost in a court ruling to allow a case to proceed regarding emailing a sequence of 3 emails to a person’s contacts to solicit them to join LinkedIn.  The judge indicated that it was reasonable for a person to believe they were agreeing to a single invitation but not 2 more follow up invitations to their contacts.  This comes on top of a Facebook lawsuit about using people’s names without their permission – they lost that one as well.

However, LinkedIn won the round in this case regarding some of the possible sources of connection referrals mentioned in my blog entry here.  A quote from the article by MediaPost mentioned below:

“The users also alleged that the social networking service violated a federal wiretap law by “hacking” into their email accounts to harvest their contacts’ addresses. Koh sided with LinkedIn on that point, ruling that users were able to “opt out of the harvesting process” before LinkedIn uploaded the information.”

You can read more at MediaPost’s Online Media Daily article on LinkedIn’s Battle Over Email Solicitation.

UPDATE: February 13, 2015  Looks like LinkedIn was unable to get all the charges in their class action suit dismissed and they’re in the middle of settling:

The social networking company and lawyers for a group of consumers say in a status report that they “have accepted a mediator’s proposal for a class action settlement subject to reaching agreement on remaining material terms and execution of a written settlement agreement.”

You can read more about this at MediaPost’s Online Media Daily article: LinkedIn Moves Toward Settling Class-Action Over Email Invitations

UPDATE: March 26, 2015  LinkedIn agreed to settle the class action suit.  The details should be available May 20, 2015 when they file papers.

UPDATE: April 17, 2015  LinkedIn has asked for a judge to toss out the ‘Add Connections’ lawsuit from a complaint filed in January 2015.  Here’s a quote from the article:

LinkedIn adds that its privacy policy says the company may use people’s “information and content for invitations and communications promoting our service that are tailored to the recipient.”

We’ll see what transpires.  Perhaps we’re all for sale on all platforms.  We are the product.

UPDATE: June 12, 2015 LinkedIn has agreed to pay $13 million to resolve a class-action lawsuit accusing it of misappropriating users’ names by sending email invitations to their friends – according to an article from the Daily Online Examiner.  Finally, in this settlement, LinkedIn has in some way acknowledged what it has been doing with your friends’ email addresses.

“The agreement calls for the company to pay $10 to each LinkedIn user who submits a claim; if more people than expected file claims, LinkedIn will add up to another $750,000 to the fund.”

LinkedIn will be changing some of its practices as a result of the settlement, including more disclosure about what it does when you click on allowing LinkedIn access to your email address books. Buyer beware from this point on…

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  1. Miss Anon April 11, 2012 at 1:52 pm - Reply

    My favorite part is when they show my profile to exes who then send me connection requests. Lovely!

    • Bhavika November 24, 2021 at 8:10 am - Reply

      When we remove someone from people you may know on linkedin then they will able to see us on their people you may know or not???

      • Kathryn Gorges November 28, 2021 at 6:01 pm - Reply

        Hi Bhavika,
        I would guess that LinkedIn is still going to show others our profiles as someone they may know regardless of whether we remove them on our own list or not.
        LinkedIn is invested in people getting more connections. So they’re going to do whatever they can to grow those from any direction possible: us or others.
        Hope that helps… I don’t have an insider view of this, but this is what I would do if I were them.

  2. Jon December 27, 2012 at 3:25 am - Reply

    No matter how careful you are with your data privacy, there is nothing much you can do about one of your friends of contacts sharing data about you on line.

    • kagorges December 27, 2012 at 12:27 pm - Reply

      Indeed — the safest approach is to consider all data online — emails, posts, pictures, videos, texts — to be public because they can become public anytime.  Maybe that’s a lesson Randi Zuckerberg just learned

  3. McP May 23, 2013 at 1:50 pm - Reply

    The algorithm thought is a nice one… but there is no way an algorithm caused the “suggested” person I just got. I’m a season ticket holder, I sold season ticket and conversed through e-mail only. I created a LinkedIn account years ago and NEVER go on their site. I still get their “connected to is connected to” e-mail spam from the handful of friends I had on their from years ago, but I NEVER go to their site, I don’t view it, I don’t view people, I don’t connect to anyone.

    Yet I magically get this “you may know” the other day containing this random person I sold season tickets to.. and I reiterate, ONLY conversed with through my e-mail.

    LinkedIn is hijacking and spying on e-mail traffic. I have already reported them.

    • Aussie Andrew February 18, 2014 at 4:30 am - Reply

      Yep I think you may be right about the spying. LinkedIn tonight told me I may know someone with whom I have no direct or indirect contacts and I hope I never do. BUT – last year I discussed a crime he had committed with a colleague. He is a scum bag BTW. Why would LI suggest him as a contact unless they were doing algorithmic spying?

      • kagorges February 18, 2014 at 1:30 pm - Reply

        Hi Aussi Andrew,
        Indeed – I’m not sure what they’re doing… Sometimes I think it’s some kind of people retargeting software: people pop up that I’ve communicated with on email but don’t know or want to know… Thanks for commenting 🙂

  4. kagorges September 20, 2013 at 9:21 am - Reply

    Some new developments around this topic — evidently LinkedIn is on the hot seat for harvesting gmail addresses. Wonder if that’s true — and if that’s only one tactic that leads to them having more information that we give them on our profile… Here’s an article in today’s news about this:

  5. kagorges June 15, 2014 at 11:47 am - Reply

    Just added an update to the end of this post about the court ruling allowing the case against LinkedIn and it’s email solicitations to proceed.

  6. unbubeebable June 19, 2014 at 11:38 am - Reply

    LinkedIn just suggested I connect with someone from the Principality of Monaco. The e-mail arrived at 6:40am on 6-19-14. I searched “Principaut’e de Monaco” at 2am on 6-19-14. I don’t use LinkedIn. Signed up back in ’04,…maybe,…not sure it has been so long. I get suggestions every now and then but rarely sign in or log on to LinkedIn. How do they know what I’m searching for at two in the morning!? This is just one of the reasons I don’t like google, facebook, or twitter. They want to share everything with everybody. Personally I’d like to see LinkedIn lose their shirts on this one.

    • kagorges June 19, 2014 at 12:56 pm - Reply

      Very creepy… seems like a backend connection potentially between Google (if you’re using Google for search while you’re logged in) and possibly you loading your gmail contacts when you first joined LinkedIn?

      • unbubeebable June 19, 2014 at 2:06 pm - Reply

        Hi Kathryn,…your caricature is nice but it doesn’t do you justice.
        The only reason I have a gmail account is because I bought a Google Play card and as much as I didn’t want to, I believe at the time, I had to sign up with gmail in order to use the Google Play card. That was within the last year. I don’t have any contacts in my gmail account that I know of, (never use it), and I know I didn’t sync it with my Yahoo account.

        What was really creepy about it,…looking up the Principality of Monaco started with an internet creep/troll in Yahoos comment section. My first thought was that this guy had tracked me down and was taunting me with a LinkedIn invitation. It took me awhile to realize the two characters were unrelated but still,…I found your article because LinkedIn had to have been screening my Google searches. Because I haven’t yet learned my lesson, I googled “linkedIn spying?” and found your article. I think if LinkedIn has the right to screen your activity on the internet,…that should be an obvious part of the agreement and certainly not in the fine print.

        I’m looking forward to seeing how the suit against them turns out and how and why they can do this. This is unscrupulous at best.

        • kagorges June 19, 2014 at 2:47 pm - Reply

          Thanks for the compliment 🙂
          We’ll see what happens with the lawsuit…makes me very curious what the underlying technology is that allows that to happen, at the same time as being slightly horrified at the casual use of that technology.

          I’ll try to keep this updated with new developments.

      • Ariana October 10, 2015 at 5:28 pm - Reply

        Logged into Google or LinkedIn? I personally searched out a name on Google and now they appear on my LinkedIn “people you may know”. I do not have a google account and have never synced my emails with linkedin (a matter of fact, I do not know the person I googled email, telephone number, etc).

  7. […] George, K. Who Are Those ‘People You May Know’ in LinkedIn’s suggested Connections?.…/. retrieved on 2014, […]

  8. kagorges November 14, 2014 at 7:18 pm - Reply

    Here’s an update to the case brought against LinkedIn for sending multiple emails to people’s friends asking them to join LinkedIn:
    The judge in the case has allowed the case to proceed — a loss for LinkedIn who was requesting a dismissal. So we’ll see where this goes next…

  9. catherinel December 9, 2014 at 6:10 am - Reply

    Great article. I don’t ever remember syncing my email account with my linkedin. A few months ago, I sent a mass email to 700 attorneys. Every now and again I get the “John Doe just joined LinkedIn. Connect with John.” Didn’t really take notice until the other day when I got one for an attorney that represented me in an accident I was in when I was a little kid. Looked at my People you may know page, and noticed that it’s FILLED with attorneys from that one email I sent.

    • kagorges December 9, 2014 at 11:01 am - Reply

      Thanks for your comment!

      Was your mass email from inside LinkedIn? or gmail? Maybe you had originally pulled in friends from gmail way back when you joined LinkedIn.

      Having LinkedIn re-affirm that it’s ok to continue to be connected to an email would be a step in the right direction for them. It’s easy to forget what we each did the first moments after joining the site.

      And of course, there’s the possibility you didn’t connect, but LinkedIn sees all… The part I don’t like about that is the permission part…and actively being transparent about what I’m permitting. Just creates an adversarial relationship that will make it easy for people to jump from LinkedIn as soon as there’s an alternative.

      • catherinel December 9, 2014 at 4:19 pm - Reply

        It was sent from gmail. And yah… LinkedIn definitely does see all.

  10. Kate January 26, 2015 at 6:11 am - Reply

    I’m still stumped as to how LinkedIn can suggest I connect with someone who runs the B&B in Cumbria that I stayed in 6 months ago even though I don’t allow LinkedIn to access either of my 2 email accounts, I’m not on Facebook, I rarely tweet (although I do read tweets) and I’m rarely logged into LinkedIn. Go figure.

    • kagorges January 26, 2015 at 12:09 pm - Reply

      Sounds familiar. Did you ever allow LinkedIn access to invite your friends? Did you check in to the B&B when you were there?
      It’s like LinkedIn has all these threads that get triggered when we do something, talk with someone, or interact online.
      Thanks for sharing that this is STILL going on!

  11. Joe 12-Pack March 28, 2015 at 7:24 pm - Reply

    LinkedIn is flat out scary. I NEVER do anything on it and I am always logged out. I have not updated my profile in 10 years.
    I have different email accounts that I use for different programs and different sets of friends (family, work, college, high school, neighborhood, etc.). In addition, the email I use for LI is different from the one I use for Facebook. And still, they find a way to suggest people I know.

    • kagorges March 28, 2015 at 10:59 pm - Reply

      I’m betting some of your friends have uploaded various versions of your emails and they’re being correlated. LinkedIn is very good at this game – they’re relevancy and business model depends on it. Thanks for commenting!

  12. atlmaddog June 1, 2015 at 10:25 am - Reply

    So is there any way to remove someone permanently from the display? There’s a person who keeps popping up in the first few rows that I absolutely despise (for very good reasons I might add) and I would like to remove this person from my ‘list’….additionally is there a way to prevent a particular person from viewing your profile and/or not allow anonymous users to view?

    • kagorges June 1, 2015 at 1:55 pm - Reply

      Hi – if you hover over the suggested connection, you’ll see a little ‘x’ in the top right corner. Click on that ‘x’ to dismiss the suggestion. That should take care of it.


      • Komrad November 5, 2016 at 11:51 am - Reply

        No, it just comes back at a later day. I have people that I clicked the X on 10 times just this week , and popped back up on the list again today.

        • kagorges November 8, 2016 at 11:30 am - Reply

          I’ll have to see if that happens to me — very annoying. LinkedIn is still not transparent about all this — in spite of litigation. Not sure why they feel a need to compromise people’s requests in order to build a business…

  13. kagorges August 21, 2015 at 10:08 am - Reply

    I just added the update to this class-action suit saga – a settlement was reached June 12, 2015. Please see above for my latest update.

  14. Janet Aldrich September 3, 2015 at 5:59 am - Reply

    I want to get rid of that box altogether … how do I do THAT?

    • Komrad March 16, 2016 at 6:02 pm - Reply

      Same. I never want Linkedin in to suggest a contact/connection again even. As in no more ‘people you may know’ prompts.

  15. Mark September 10, 2015 at 8:02 am - Reply

    Just an observation. LinkedIn has just suggested the points loyalty system for Eurostar trains as a potential person I may know. I have only ever RECEIVED emails from this address, and then only to my Outlook account. I did notice that despite saying “no” when installing the Android client, the “sync with contacts” option was mysteriously checked, but then someone I happen received an email from isn’t a contact!

    They are clearly deeply harvesting data from my phone and ignoring privacy options I choose!

  16. Laurina September 24, 2016 at 4:45 pm - Reply

    I’ve got suggestions of people met once in real life through a dating website.
    The email used for the dating website is different from the one I use for linkedin (and all “working matters”). Anyhow, none of them had my email.
    None of them did know my surname.
    We have zero connections in common.
    My linkedin is not connected to any phone number they might have had (in fact, it is not connected to any number at all).
    Why the hell are those 3-years-ago-1-drink-dates-and-goodbye showing up on my suggestions?!
    That’s wierd, let me tell you.

    • kagorges September 24, 2016 at 5:09 pm - Reply

      Hi Laurina,

      That’s very strange… I can only think of a few ways to connect these up: the dating site sells the list but sends it to a company who cleans and fills in the list using web scraping software to put 2+2 together. Or perhaps LinkedIn does that. Maybe they do that connecting up via IP address — that information is readily available when you visit a site and can be matched up among list records.

      All in all, it’s disconcerting to be so closely tracked — and of course, upsetting to see someone you don’t want to connect with pop up in front of you and you actually know them.

      Thanks for posting your experience,


  17. James Kabala May 14, 2017 at 4:17 pm - Reply

    I often get suggestions for former students whom I had years ago, in most cases before I had a LinkedIn account. I never looked them up on LinkedIn. I have never had them in any kind of contact list. I am a bit of an e-mail hoarder who might still have old messages from them in my Inbox, so that must be how LinkedIn knows about them.

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