What does HackerNews think of thumbor?
thumbor is an open-source photo thumbnail service by globo.com
Another point is that holding onto the unmodified images server-side (and merely serving a cached, resized, optimized version on the fly) can be beneficial for future use cases.
Check out, e.g., Thumbor [2] if you're curious to see more of the complexities involved. I have self-hosted it for a company before, and it worked well.
There are some commercial services in this space, as well as other similar open source services.
If you're looking for a quick way to get thumbor up and running with docker, I'd plug https://github.com/minimalcompact/thumbor
We switched to host our own thumbor (open source), and couldn't be happier. We pay around a quarter or less than before (even with failover in place) as well.
We really wanted to use a hosted service. We're not keen on hosting stuff out of our core business. But in this case it just didn't work out.
EDIT: link to Thumbor https://github.com/thumbor/thumbor
About Grid, it seems the images are stored on FTP. Am I right?
I look for a solution like these, but more flexibe, where I could host my images on AWS, Azure, etc.
At globo.com we have near a billion images (we are a big portal). Can you imagine pre-generating that many images every time a new format gets added?
We serve everything with thumbor with a Varnish cache in front of it and we're very happy with it. It has enabled our designers to work with any image size they can think of.
If you guys need more info, please check thumbor's docs: https://github.com/thumbor/thumbor/wiki/