Out now iOS · watchOS

Kaeru

変える

Currency Exchange for iPhone, Widget & Apple Watch

The smartest currency exchange app. Convert between 50+ world currencies instantly. Whether you're traveling, shopping online, or just curious about exchange rates, Kaeru gives you accurate, real-time data in a beautiful interface.

Download on App Store

Available on iPhone, Apple Watch & Widgets

One payment, no subscription

See it in action

A quick look at what Kaeru can do

Features

Everything you need to convert currencies on the go

50+ World Currencies

Convert between currencies from the Americas, Europe, Asia-Pacific, Middle East, and Africa. All major and minor currencies covered.

Real-Time Rates

Always accurate exchange rates from a free, open-source currency API. Rates update automatically so you're never working with stale data.

100% Offline Support

Cached rates let you convert currencies even without an internet connection. Perfect for travel in areas with poor connectivity.

iPhone Widgets

Small, medium, and lock screen widgets to check rates at a glance without opening the app. Always your most important pair right on your home screen.

Apple Watch

Full Apple Watch app with Digital Crown support for adjusting amounts on the go. Currency conversion right on your wrist.

Conversion History

Your last 100 conversions saved automatically. Review past calculations and pick up right where you left off.

How It Works

Pick Your Currencies

Choose your source and target currencies from 50+ options worldwide. Save your favorites for instant access next time.
Drag to Adjust

Use the intuitive drag control with haptic feedback to adjust amounts, or just type directly. Real-time conversion as you go.
See All at Once

Multi-output mode shows your amount converted into all your favorite currencies simultaneously. Perfect for comparison shopping while traveling.

Frequently Asked Questions

What is Kaeru?

Kaeru (変える) is an iOS currency converter app by Quantum Quacks. It supports 50+ world currencies with real-time exchange rates, cached offline rates, home-screen and lock-screen widgets, and a full Apple Watch companion app.

Does Kaeru work without internet?

Yes. Kaeru caches the latest exchange rates so you can keep converting currencies even without a connection. It's designed for travel in areas with poor connectivity.