KaiOS Design Notes: UX observations from a feature phone

In IndiaFOSS 2025, I introduced KaiOS feature phones, which are capable of many things a smartphone can do including (theoretically) opening websites and webapps. Hearing this, people often assume that any webapp can be used on KaiOS. However, this is usually not the case.

Even if an app or website technically works (without breaking due to using modern JavaScript features that the old KaiOS engine doesn’t support) webapps often expect touch or mouse interaction rather than the keypad interaction that KaiOS devices provide. This requires design that is—not more or less difficult, but different from what most people are used to. If you have used any old Nokia phone, you may have an idea what kind of design and interaction I am talking about!

Over the past year, I have been redoing the user interface of Convo, my XMPP powered messaging app for KaiOS. Along the way, I have been paying a bit more attention to how other KaiOS apps handle user interaction.

In this talk, I will briefly go over some common design patterns that feature phone apps use to make KaiOS more pleasurable to navigate.

• Keypad-operated phones have their own form of user interaction that is different from touchscreen or mouse based interaction.

• Softkeys let the user select between primary options

• Use keypad shortcuts to make sure each key is used to the maximum! (But also a more traditional dropdown menu so the less shortcut-inclined can still navigate)

• Designing for small screens tends to have less focus on how something should look and more on what should be presented when and where