
Ask HN: FB suggests friends after visiting same city, don't use FB phone. How? - shafyy
Facebook suggested two new friends two days after we hung out together in a city. They are my co-workers.<p>I moved recently to this city (4 months ago). I don&#x27;t have the FB app or use FB on my phone, don&#x27;t have this city set as my location in my FB profile and didn&#x27;t check-in into a location on FB. I never allowed FB on my laptop&#x27;s browser location access. I followed a page from a local comdy club, though.<p>Other than that, I have WhatsApp and the Oculus app on my phone a. I have an iPhone.<p>Any ideas how they know that we have been geographically close? Is it possible they use WhatsApp&#x27;s location info to match this? I have  given WhatsApp location access while using the app.
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etempleton
You are missing the most obvious and most likely reason for matching with new
coworkers. Your new coworkers searched and viewed your profile on Facebook
after meeting you. This is a key way Facebook suggests friends.

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doopy-loopy2
this. so obvious yet we jump to conspiracy.

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DudeInBasement
It's so obvious that it's reptiles, yet we jump to a simple search on
Facebook.

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dnh44
It could be WhatsApp but I think it would be trivial to figure this out any
number of ways.

You have a Facebook account, if you don’t check it on your phone presumably
you do on your notebook or desktop. You probably browse the internet at home
from the same WiFi network with both your computer and phone. Different
cookies from the same IP address would indicate the same household. It
wouldn’t take a lot more to know they belong to the same person. IP addresses
can strongly correlate with a geographic area.

Since nearly every website has those social media buttons Facebook can track
you from site to site even if you’re not logged in.

For sure Facebook knows where you live and has matched up your facebook-free
phone to your Facebook account.

I’ve got no experience with actually doing any of this, it’s just what seems
obvious to me. I’m sure the whole truth of it is much scarier.

I haven’t had a Facebook account in over a decade but my current girlfriend
had my ex-girlfriend from 15 years ago pop up in her recommended list. We live
about 10,000 km apart.

If there are any Facebook engineers reading this I must salute you. Your work
is amazing.

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arcturus17
I used to date girls on Tinder with at least a few degrees of separation (ie,
no friends in common), didn’t have Tinder and Facebook connected in any way,
and the dates would still show in my friend recommendations list.

It was WhatsApp.

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sopromo
I think that your example is not correct.

Tinder and a lot of others apps share information with Facebook about what you
do by using their SDK.

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arcturus17
How would they do that if I didn’t log in with Facebook or in any way connect
the apps together?

What I did do is add those girls’ numbers on WhatsApp - which is a Facebook
property - and they suddenly appeared as friend recommendations.

But if there is any definitive proof it’s that I only was recommended the ones
that I had messaged on WhatsApp, never those that I had only chatted up on the
Tinder app...

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sopromo
Each phone has an unique advertisement identifier, they could link you across
several apps with that.

But it may be very possible that they do a combination of everything to track
you (whatsapp, instagram, facebook, oculus, apps that use the sdk...)

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lacker
My guess is phone number matching. Your friends use Facebook on their phone
and added your contact information recently. That’s enough for Facebook to
figure out that it’s a potential match, given that you already have some
friends in common.

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readyoursicp
Is it possible your friends searched you up?

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netsharc
Did you add each others' numbers on WhatsApp?

Or if you moved due to work and you got added to a company-wide address book
which is also synced to employees' phones and in turn got synced to WhatsApp,
Facebook's systems could probably match up names to suggest a connection.

Although, why only these 2 people and not others from the company? Scarily
there's probably enough data between you 3 for FB to know that you would be
compatible with each other, so maybe Facebook figured the same thing you 3
figured out in real life -- you hung out with each other so I would deduce you
found these 2 co-workers interesting. But I doubt anyone got paid to make such
sophisticated stuff, there's probably a simpler logic that offers a quantity
but not quality of "friends".

I still want to write a short story that starts with a guy saying "OK Google,
get me a girlfriend", and an algorithm that slowly pops up suggesting events
and locations for him to visit, knowing that a girl that he'd be compatible
with will be at the events/locations...

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codegeek
You visit a website and if they have fb pixels/tracking, it is very easy. FB
is everywhere, EVERYWHERE.

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jmngomes
uBlock Origin is pretty effective for that issue:
[https://addons.mozilla.org/en-US/firefox/addon/ublock-
origin...](https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/)

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NVHacker
Download your FB information and scan through it. If you can, ask your
colleagues to do the same. FB tracks the websites you are visiting so the
local comedy club website is a possibility.

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aminozuur
If I create a brand new Facebook profile, and I never tell Facebook my
location (neither via my browser geolocation or profile info), however most of
my Facebook friends that I chat with daily live in a town called Hackerville.
I've never installed or used Instagram or Whatsapp.

Guess where Facebook thinks I'm living?

They can be pretty sure I either grow up or live in Hackerville.

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winrid
FB could buy your data from other networks, provided via some other app.

Also your coworkers probably looked at your FB profile.

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netsharc
This freaking sucks, I use one "for junk" email address for online shops, etc,
but it's also the email I use for Facebook. Facebook opened its "Data
Disclosure" section a few months ago, and mine had a list of many companies
which uploaded their customer data to Facebook and probably could target me...

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beamatronic
I think even your cell phone location data by IMEI is available for sale these
days.

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ta17711771
Journalists etc have purchased it reliably for like...$300 if I recall
correctly.

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mifreewil
It’s really impossible to know without more info, as people have mentioned you
can download your fb info for some clues. One possibility I haven’t seen
mentioned is they are using your credit card data that they’ve purchased.

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parliament32
Either WhatsApp or Instagram.. all FB properties share a common user graph. Or
your friends searched for you on FB.

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vopi
I suspect it's through a Bluetooth beacon. Basically analytics/trackers for
physical stores.

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joemazerino
Sounds like WhatsApp and/or your phone number connecting the dots.

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thinkingemote
Local comedy club plus shared friends.

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MintelIE
Voice recognition, cameras always on and recognizing, could be a million
things.

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yolomcsuperswag
My guess is WiFi-triangulation by WA. Just a guess, though.

