UnitX
Making everyday conversion feel immediate

Back in 2025 I was in Japan, and my converter app stopped working the moment I lost signal.

I use one constantly, most of all when I travel - which is exactly where mine gave up. That was the push. I installed the first twenty converters the App Store offered me and audited them properly. They were mostly the same app: cluttered, years out of date, and unable to finish the one task they exist for without a banner ad in the way. Favourites sat behind a paywall. History and Apple Watch support were rare. Almost none of it worked offline. UnitX is the converter I wanted on that trip: an answer straight away - no network, no ad, no form to fill in first.

• Where it started Twenty of the top-ranked converters, installed and used before any design work began
• Audience People converting measurements or currencies in the middle of another task
• Product challenge Give the answer immediately, offline and unblocked, while keeping exact manual conversion one tap away
• Platforms iPhone with an Apple Watch companion for repeated utility moments

Start with intent. Offer control when it helps.

I built the main surface to take short requests like “72 kg to lb” or “5 miles in km.” Manual controls sit beside it as a parallel route, not a buried fallback, and voice and camera entry take the typing out when the number is spoken or printed.

The twenty apps wrote the brief.

Every row below is a reason I put one of them down, and the decision it produced in UnitX.

A single converter, with several useful ways in.

I kept one outcome - the answer - and let the way in change with the moment. The iPhone screen shows intent-led suggestions alongside the manual, microphone, and camera flows; the iPad view makes the same navigation model visible at a larger scale.

Every rating it has had so far is five stars.

UnitX is live on the App Store, free, and holding a 5.0 average across 25+ ratings. The part that matters more than the number: people who never read this page keep naming the three things the audit set out to fix - that it works without a signal, that nothing is sold to them on the way to an answer, and that it stays out of the way.

What a five-star average does not tell you.

• The pool is tiny, and that is the real problem The listing is barely surfaced in the App Store - impressions run in the twenties and thirties - so downloads are low and 25 ratings is what a small user base produces. The number is honest; the sample behind it is not large enough to carry weight on its own.
• Ratings are self-selected People who bother to rate a free utility are not a cross-section of the people who opened it. Nobody who downloaded UnitX, found it unhelpful and deleted it is represented anywhere in that 5.0.
• It measures liking, not the thing the design was for A rating says people are pleased. It does not say a conversion took fewer steps, or that intent-led input beat the manual route. Neither is instrumented, so this page cannot claim either.
• The constraint is distribution, not the product The evidence such as it is points at a product people like once they find it, and almost nobody finds it. That makes the open problem discovery and App Store visibility rather than interaction design, and it is where the work is going next.
• "Every rating so far" has an expiry It is true at the time of writing and will stop being true. The claim is a snapshot, not a property of the app.

Flexibility works only when the default remains calm.

I kept the common request light, and left reliable ways out of it: manual input, an editable result, history, favourites, and Apple Watch follow-through. What I still want to test is how well recognition recovers when it misreads something, and which repeat conversions actually earn a place on the wrist.