Why it's quick
For the technically curious: what makes it fast, and why we bothered.
Most photo book tools feel slow, and after a while you stop noticing, the way you stop noticing a heavy door. We noticed, because we knew it didn't have to be that way, and keeping it quick became one of the things the whole design is arranged around. Here, for anyone who likes the how, is what that means.
The biggest decision is where the work happens. In RGBloom, the editor runs on your device, in your own browser - not on our servers with your screen as a puppet. When you drag a photo, resize it, or turn a page, that's your own machine responding, not a request travelling to a data centre and back. Round trips over the internet are where a lot of the sluggishness in web apps comes from, and we've simply removed most of them: while you design, there's almost nothing to wait for, because there's almost nowhere for the work to go except the device in front of you.
Photos are the heavy part, so they get the most care. A modern phone photo is large, and decoding a pile of them can jam up a page if you do it carelessly. We do that work on background threads, so the interface stays responsive while your photos are read and prepared. And we keep a few sizes of each photo - a small one for thumbnails, a medium one for the editor, the full one held back for print - so the screen is almost never pushing around more pixels than it needs. You get something sharp to look at quickly, and the full-resolution version is spent where it actually matters, on the printed page.
Because nothing is uploaded until you order, none of this waits on your connection either. That's the point that matters most on a phone: a lot of tools begin sending your photos to their servers the moment you add them, which on a normal mobile connection is exactly when everything grinds. We don't, so we don't. When you do order, there's a single upload of the finished book, and we work to make that quick too.
The neat part is that fast and private turned out to be the same design. Keeping the work on your device is what makes it responsive and what keeps your photos off our servers until the last moment - one decision, two payoffs. We did the harder engineering because we thought your time and your data were both worth not wasting.