Very few of us are what we seem. Agatha Christie, The Man in the Mist

Feel free to browse around and you’ll have a pretty good idea of what this is about. I write about security, privacy, vulnerabilities and exploits, retro computing, music, various programming languages, personal projects and general stuff that crosses my mind. Make sure you use encrypted email when sending me any sensitive info.

I am not a pirate, but a corsair.

Check out this website’s privacy policy and/or subscribe to the RSS 2.0, Atom or JSON feeds.

Here are some dogs running.

Here are some dogs running.

Why sizeof(cat)?

Because +++ATH0 was taken.

Why not typeof(cat)?


PGP key

0xEC61D381F2735495 and you can download the public key.
The key’s fingerprint is 4ED4 000C 9038 2C23 D417 8CB9 EC61 D381 F273 5495.
The key should expire on June 2, 2027.


Please send me encrypted mails if possible (see my public key above). Every bit of encrypted traffic increases the encrypted background noise and thus makes it harder to distinguish between important and unimportant traffic.

If possible, one of:

$ gpg --keyserver hkps://keys.openpgp.org --recv-key 4ED4000C90382C23D4178CB9EC61D381F2735495
$ curl -sf https://sizeof.cat/sizeofcat.asc | gpg --import

And send me an email.

I especially love the emails asking if I am really a cat (no, i’m not a cat but if it’s important for you to talk to one I’m pretty sure we can work something out, my Monero address is here) or if I can download this PDF file from this totally legit website (sure, why not, what could go wrong) ¯\_(ツ)_/¯.

/* Let's do this in JavaScript because everybody knows JS. */
const domain = "riseup.net";
let email = "sizeofcat" + '@' + domain;
/* Yes, that's my email address. */

Maybe you like the console more.

$ printf "%s@%s.%s\n" sizeofcat riseup net

Not a JavaScript programmer and/or can’t figure it out? Click here.


Nothing else except those, I don’t have a Facebook, a Discord, an ExpertSEXchange, a MySpace, a Gitlab, a GetHobo, a Masto-something, a Twitter, a Twatter, a Swatter, a Fatter, a Squatter, a Platter or whatever is the latest fad nowadays. If somebody claims to be me, chances are it’s not actually me.


If you like the work I do and would like to support it I’d appreciate contributions via Monero (you can send Monero to sizeof.cat in an OpenAlias compatible wallet).

Monero is an open-source cryptocurrency that focuses on privacy, decentralisation and scalability. Unlike many cryptocurrencies that are derivatives of Bitcoin, Monero is based on the CryptoNote protocol and possesses significant algorithmic differences relating to blockchain obfuscation.



I started this website in 2015 (as you can see from the archive) and managed to piss off quite a few companies corporations along the way (looking at you Twitch/Amazon, Samsung and Apple), which has to be a bonus, I mean who doesn’t want more friends? The website is powered by Hugo (and a bunch of Python scripts behind) with a custom theme based on the Even theme by olOwOlo, custom theme which I am also releasing for free. Free is always good.

The access logs are disabled, so there is absolutely no trace of any of the visitors of this website but if you want a number, I’d say over 70k unique monthly visitors and over 250k monthly requests.

If you want to make me an irresistible offer to promote (read: shill) your product, make sure you use the email subject IRRESISTIBLE OFFER, all in caps, so my email client can pick it up and mark it as spam.


Sometimes I feel like I don’t even know who sizeof(cat) is. But then I remember sizeof(char) is always 1 and my brain relaxes. TwitterUser967_Totally_not_b0t

sizeof(cat) is my idol. Nagoor Babu, Weapon of Durgasoft

I have no fucking idea who sizeof(cat) is. Abdul Lateef Jandali

sizeof(cat) once broke into the Octagon servers using nothing but a bottle opener, sauerkraut and the famous left-handed Latvian Rotator Torture. Doug Snowmen

sizeof(cat) is not a meaningful question in itself because cat is not a data type or a variable. In programming, the sizeof operator is used to determine the size in bytes of a data type or a variable. For example, sizeof (int) would return the size in bytes of an integer variable. If you are asking about the size of a domestic cat, the answer would depend on the specific breed and individual cat. Generally, cats can weigh anywhere from a few pounds to over 20 pounds, with an average weight of around 9-10 pounds. Chat Geppetto



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All images are compressed to lossless quality with metadata removed, if you place them on your website please make no changes. You should download and place the images on your server (for security reasons) instead of hot-linking, but use them how you see fit.

GIF (240x60) with black/white background


JPEG (240x60) with black/white background


JPEG (88x31) with black/white background


PNG (240x60) with transparent background and black/white text


PNG avatar image with various sizes (32x32, 64x64, 128x128 and 256x256)


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