We use Bytescale to host and optimize images for all of the dynamically generated content on our site. All images go through Bytescale, so I work daily inside with their Image Processing API and URL-based transformations. We upload assets using their APIs which we've integrated directly into our site; we had been using their plug-and-play widget, which is great for quickly implementing uploads in your app, but have since written our own upload workflow using their headless SDK. Even though we've written our own UI, having an SDK you can just "throw a BLOB at" and have it uploaded and transformable is still a massive time saving. The most valuable features for us are transforming images by URL parameters. There's a lot of options so I reached out to their support for the best combination to use for our use case, and they provided a set of parameters that are file-size focused (you can also tune for processing-time focused, among other things, so it's worth getting these right). Image processing reliability and service uptime have been great; we used another vendor for a while and occaisonally there would be images that would crash their image processing pipelines (we'd get an error e.g. due to input images being too large) but haven't had this since moving to Bytescale. We even tested a few known problematic images, and Bytescale handled them fine.

Uploads, transformations, delivery, and security are all rock-solid, fast, and clearly built by people who have taken time to think about developer workflows. Service performance, reliability, and uptime have been great; there have been no service outages and we're consistently getting fast asset load times (TTFBs on media assets in the single digits and low double digits, which is about as fast as you can get).

Initially we were pitched this amazing alternative to competitors.