What you need
- Multimeter for macOS 13 or later, $19.99 once.
- Nothing.
Set it up
- Add a Web Address meter with your two currencies in the address, and the key path
rates.EUR(the second currency):Web addresshttps://api.frankfurter.dev/v1/latest?base=USD&symbols=EUR - Refresh every hour. The rates change once each working day, around 16:00 in Frankfurt.
Multimeter settings
In Customize This Meter… (from the meter’s menu):
| Setting | Value |
|---|---|
| Source | Web Address |
| Web address | https://api.frankfurter.dev/v1/latest?base=USD&symbols=EUR |
| Key path | rates.EUR |
| Refresh every | 1 hour |
| Label | EUR |
| Face | Label & Value or LCD Readout |
Tested: Run on October 29, 2026: 1 USD = 0.89847 EUR.
More on this source, including every format it reads, in the Web Address guide.
Limits
- Reference rates, published once a working day: good for budgeting, not for trading. For a rate that moves all day, use the stock recipe with a ticker like
EURUSD=X.
Variations
Other currencies
About 30 are covered, including GBP, JPY, CAD, AUD, CHF, INR, MXN and BRL. Change base and symbols, and the key path.
Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
| No number found in the response | The key path doesn’t match the reply. | Run curl -s with the address and read the JSON. Dots walk into objects, numbers pick array items (items.0.count). |
| Couldn’t reach the address | No network, a typo in the host, or the service is down. | Open the address in your browser. Multimeter tries again at the next refresh. |
| The server answered 404 or 422 | A currency the ECB doesn’t publish. | Check the list at frankfurter.dev. |
Questions
Why doesn’t it change on weekends?
The European Central Bank publishes rates on working days only.