Purrank – Cat & Image Pranks per Gredon

Purrank is a harmless prank extension. Every now and then it changes how a picture or video looks on the web pages you browse: upside down, pixelated, blurred, swapped for a funny cat, or hidden behind a fake NSFW filter. It is subtle by default, so it's easy to miss at first.

Purrank never posts, saves or changes anything on a website. It only changes what this browser shows, until the page is reloaded or you click Restore page.

Five pranks

• Rotate: the picture turns upside down. You can also allow sideways, a slight tilt or a slow spin.
• Cat: the picture is swapped for a funny cat photo or GIF (or a short cat video on reddit.com), cropped to the same size so the page doesn't jump.
• Pixelate: big chunky pixels over the original. Videos keep playing.
• Blur: out of focus, as if their glasses need cleaning.
• NSFW: the picture is blurred behind a fake content filter styled to blend in with the site (a pill button on reddit.com, a round badge on Google search, a neutral "Sensitive content" cover everywhere else). Purrank draws it itself and uses no site logos or artwork. One click shows the original. It is only a cover over an ordinary picture: no adult content is ever loaded or shown.

How it behaves

• Runs on all websites (http and https), in the main page only. Pictures smaller than 64 px (most icons and avatars) are left alone; the minimum size is adjustable.
• Subtle by default: each image or video gets a 5% chance, decided just before it scrolls into view, so the prank is already in place when it appears.
• Presets: Subtle (5%), Mischievous (15%) and Chaos (50%, plus the occasional prank in plain sight).
• Fine-tune it on the options page: a Prank mix slider for each kind, rotation styles, start delay, max pranks per page, per-site limits, minimum image size and an optional vanish-on-hover mode (a pranked picture quietly goes back to normal when the mouse reaches it).

Stay in control

• Toolbar popup: turn pranks on or off, pick a preset, pause on the current site, prank a visible picture right now (Cat, Rotate, Pixelate, Blur, NSFW) and Restore page to undo everything.
• Excluded sites: automatic pranks never run on the sites you add, such as banking or work tools.
• Test drive: try every prank on built-in sample pictures without touching a real website.
• Reloading a page undoes its pranks. Removing the extension stops Purrank for good (reload any open tabs).
• Nothing happening? Check about:addons > Purrank > Permissions and allow access to all websites.

Where the cats come from

• Internet cats (default): a local cat stash of up to 600 photos, GIFs and short videos from SFW cat subreddits (12 by default, such as r/catgifs, r/StartledCats and r/Chonkers; the list is editable). Posts marked NSFW or spoiler, quarantined or removed are skipped, and stashed posts that get flagged later are dropped.
• When the stash has nothing suitable: random cat photos from cataas.com, then eight cartoon cats that ship with the extension.
• Pick "Cartoon cats" as the cat source to keep Purrank completely offline.

Network and privacy

• To fill the stash, Purrank requests public subreddit listings from www.reddit.com right after installation and then about every 6 hours, and also from a reddit.com tab while you browse Reddit. The browser sends its Reddit cookies with these requests, because Reddit often blocks anonymous ones. Purrank never reads those cookies, posts nothing and reads no account data.
• Cat pictures load directly from Reddit's media servers (redd.it) and, as a fallback, cataas.com, always requested without a referrer, so these servers are never told which site you're on. Cat videos are only used on reddit.com itself (and in Test drive).
• Settings, the prank counter and the cat stash are stored locally in the browser.
• No analytics, no ads, no tracking, no account and no developer servers. Nothing is ever sent to the developer.

Play nice

Only install Purrank on a browser you own, or with its owner's OK. It never hides: its button stays in the toolbar and it's listed in about:addons. Purrank is meant as a friendly joke. Prank people who will laugh about it, keep important sites excluded, and think twice about the NSFW prank on work or school computers or during screen shares (set NSFW to 0 in the Prank mix if in doubt). Come clean eventually: the popup's prank counter makes a nice reveal.

Reddit and Google are trademarks of their respective owners. Purrank is not affiliated with or endorsed by them.