Letterboxd keeps its API closed. We wrote to them asking for brand permission and for access, and they gave us both. Everything the app does depends on that conversation going the way it did.

Most apps of this kind generate an image and leave you to save it, open Instagram and post it yourself. We integrated the Instagram API instead, which meant stories could be built in layers and sent directly. The difference is small to describe and large to use.

Reviews vary wildly in length. A two-line reaction and a six-paragraph essay both have to become something readable inside a nine-by-sixteen frame.

Rather than force one layout to handle both, we designed a set of them. At least one holds a full review of any length by shrinking the type as far as it will go. The others set a limit and truncate past it, trading completeness for a type size people will actually read. The user picks which trade they want.

The in-app editor started deliberately limited. What it has now came from requests: more typefaces, different text alignments, adjustments users asked for directly and got.

The app launched on iOS only. Android came later for the same reason.