The Day One editor on Android, rewritten from scratch ✳︎ one designer, one developer, one month.

The surface everyone touches

Being a journaling app, Day One is only as good as its editor. Every entry starts there, and for years the Android app wrote entries through Aztec, an aging rich text editor that never felt at home, especially once Android moved to the M3 design system. I wanted an editor that was ours, something native and fast, built in the app's design language and rethought from the ground up rather than reskinned.

One month, two people

A developer and I took it on as a sprint, one month to redesign and rebuild the entire editor, every formatting option and every attachment type, shipping piece by piece while people kept journaling in it. Working that close to the implementation meant decisions landed the same week they were made. I personally closed the month at 37 pull requests, 32 in the app and 5 on the backend.

A mode for writing, a mode for reading

The old editor was always editing, and common reports were that users weren't sure if edits were saved before leaving the editor. This was in contrast to the iOS editor, which had a “Done” button. In reality, syncing is smart and edits are rarely lost, but psychologically the “Done” button provided the same safety as a “Save”. The rewrite splits writing from reading, and in edit mode the top corner holds a primary checkmark instead of a back button, so finishing an entry is an explicit accept. It sounds small. It changes how safe the whole editor feels.

Formatting that knows where you are

Before, formatting options were shown persistently in a horizontally scrollable bar above the keyboard. I split them into 3 groups: options that only make sense with a selection, structural options like headings and lists that live under a menu, and immediately useful options that follow context. This massively reduced the cognitive load of using the editor and finding formatting options that are relevant to where your cursor currently is.

A voice that can edit

The editor also gained an AI voice mode that takes agentic turns. It can read your entry, search it, and edit it through tool calls, so all you have to do is ask. The goal was entry omniscience and omnipotence, an assistant that sees everything and can change anything on your behalf. You talk, it journals.

"He's probably the best designer I've ever worked with. As an Android developer I appreciated his knowledge of the platform and that he treated all platforms as equal. I feel like we could work together instead of against each other and the result reflected that."