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, 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.

PGP key

0x4E2294B480A2C731 and you can download the public key.
The key’s fingerprint is D7BB F1EE E7B6 2BB9 8079 F768 4E22 94B4 80A2 C731.
The key should expire on November 28, 2025.


If possible, one of:

$ gpg --keyserver hkps://keys.openpgp.org --recv-key D7BBF1EEE7B62BB98079F7684E2294B480A2C731
$ 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 a cat I’m pretty sure we can work something out, my Monero address is below) or if I can download this PDF file from this totally legit website (sure, why not, what could go wrong).

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

/* Or ...*/
const secondary_domain = 'disroot.org';
let secondary_email = 'sizeofcat' + "@" + secondary_domain;
/* ... use my secondary email address. */

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 Github, 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, but my evil twin, typeof(cat).


Feeling rich today? Let’s fix that.

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 the sizeof.cat website in 2015 (as you can see from the archive) and I 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, 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.



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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.

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)


SVG image (100% width, automatically fills the container)


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