I made a web-based graphing calculator (http://fooplot.com) in 2007 that runs on ad revenue and is still delivering about 5X its hosting costs. It only makes enough profit for about a few dinners a month so nothing I can live off of but hey I'll take anything more than $0. It used to make an order of magnitude more back when I had 250K MAU and that was a meaningful addition to my meager PhD salary. But times have changed and (a) people started using mobile apps to graph functions and (b) AdSense somehow decreased the CPC I was getting and I then stopped putting effort into it.
You can put arbitrary equations into the URL, e.g.
Kind of curious how that works, the url does not match what you land on so I'm guessing something intercepts it but it outputs a unique url? It's not just urlencode anyway.
Are they precomputed to save resources or something?
Pretty neat
I wrote the whole thing from ground up. I don't think I remember seeing any libraries back then. It actually initially used 1-pixel DIVs, then SVG, then later changed to canvas.
You can put arbitrary equations into the URL, e.g.
http://fooplot.com/1+sin(x)/2