Juha Saarinen: Find out what Facebook and others know about you

Personal data exploration isn't a great feeling, but that's life when you're the product. Photo / 123RF

The Cambridge Analytica and Facebook scandal is still on the boil, which is good as more people are asking themselves what they have uploaded to the social network, and other online services.

Not that anyone can get a good answer to that question by logging on to Facebook, and clicking around. You don't get a good overview of what data Facebook stores on you that way.

Instead, download your data from Facebook. To do that, head over to this web page: https://web.facebook.com/settings and click on the "Download a copy of your Facebook data" link.

You're asked if you want to download a compressed archive of your data, have to enter your Facebook password and warned to keep the information safe and secure; heed that warning, because the file you'll receive contains sensitive data on not just you but your friends as well.

Thanks to Facebook's superb open source software, the social network's servers quickly packaged up a data bundle for me.

On UFB, downloading the large, 618.5 megabyte archive was quick and easy. Uncompress the information, and you see that Facebook organises the information nicely, as web pages.

Now you can get a better idea of the wealth of data Facebook has on you - and to a degree, which advertisers have some of your info as well. I mean, why does KLM's Ghana office have my contact details?

Your timeline posts, comments, photos, videos, the ads you clicked on, and much more are there. There was plenty of old stuff I had forgotten about and no longer recognised what it was. Facebook remembers it all, and its algorithms can join the dots though, even if you can't.

There's such a lot of data though. Keeping track of it would be a full-time job really.

I was somewhat alarmed to find a long list of my contacts, with phone numbers and email addresses, in the archive. The list looked like it was compiled over the years, as some entries were really old and no longer in my existing contacts book.

Where did the contacts list come from then, and when was it uploaded? The archive didn't tell me that. Searching for how to delete imported contacts led me to the settings for Facebook's Messenger program (https://web.facebook.com/mobile/messenger/contacts) and the list I found there looked very similar to the one in the archive.

I don't remember doing it, but I had given Messenger permission to access my phone contacts. Messenger faithfully uploaded them to Facebook, and kept every single record over the years, including ones that I no longer had on my phone.

At least Facebook didn't have my call records, which is what Wellington developer Dylan McKay found in his data archive.

https://twitter.com/dylanmckaynz/status/976368845635035138 Others found call records too in their archives; as a journalist I would feel very uncomfortable if Facebook knew whom I spoke and when, and would be compelled to delete my account if that was the case.

The long and short of it: you should definitely download archives from Facebook, Twitter, Google, LinkedIn and other services that keep personal information.

Then when you know what's there, use a search engine to learn how to delete the data that's stored online, things you don't want to share. Once again: please keep the downloaded data safe.

It's a sobering experience to see some of the data that's held on you, laid out clearly. I say "some of the data" because I have no idea where all the information connected with me is.

Nor do I know what warped assumptions automated algorithms derive from my data, quite a bit of which is outdated or silly rubbish. If Cambridge Analytica used my data, their profile on me would've been laughably wrong.

Personal data exploration like the above gives you a feeling of being an involuntary part of larger systems that you have very little control over, let alone say in. It isn't a great feeling, but that's life when you're the product.