Currency converter for travellers
Live exchange rates for 152 countries, and they keep working when the signal doesn't. Then the surprise: the number you typed is also a temperature, a distance and a weight — every unit answers at the same time, so you never pick a mode first.
$9.99 once, after a two-week free trial. No subscription, no ads, no account.
Exchange rates
A converted number with no provenance is a rumour. Convert Once fetches a live rate when there is signal, keeps the last good table when there isn't, and carries a rate table compiled into the app itself — so it answers on the very first launch, on a plane, with no network it has ever seen. Whichever of the four you are looking at, the app says so, and says how old it is.
Fetched just now from a public rate feed. No key, no account, nothing about you in the request.
The last table it managed to fetch, stamped with the time it arrived. What you get in a basement or on a train.
Compiled into the app. Means a brand-new install works at 38,000 feet before it has ever touched Wi-Fi.
The rate you were actually given at the counter, typed in by hand. It outranks all three of the above, permanently.
The magnitude rule
One number answering every unit only works while the answers stay readable. Nobody types 1,500 and means degrees. So every tile is graded against the size of the number — not a guess about you, a statement about the physical world — and the ones that are not a real thing at that scale get out of the way.
Tipping
A 20% button in Tokyo teaches the wrong thing. Convert Once carries the actual custom for all 152 countries — including whether a service charge is already on the bill, and whether tipping would be an awkwardness rather than a kindness. Tour guides get their own entry, because a guide's custom is frequently the opposite of the restaurant's.
The rest of it
Like the weather app. One location fix per launch, on the device, to work out which country you are standing in. Never stored, never sent anywhere.
The rate on the airport board is rarely the rate you were given. Type in the one you actually got and it outranks every source, for that currency, until you clear it.
A price typed before the phone went into your pocket is one you have walked away from. A stale figure over the keypad is worse than an empty one.
Here and home, side by side, with the day difference — because the question is never "what time is it there", it is "can I call them".
Siri, Spotlight and the Shortcuts app answer conversions, rates and tipping. Put it on the Action button and it is one press from anywhere.
The rate for wherever you are, how old it is, and what tipping means there — on the home screen and the lock screen.
Price
Once. Not a subscription.
Two weeks free — plenty of time to realise how much you'll use it, even in your home country.
iPhone and iPad · iOS 18 or later
Convert Once