Migrate from Open Exchange Rates

Open Exchange Rates authenticates with an app_id query parameter and returns a USD-based snapshot by default. Its latest.json payload pairs an epoch timestamp with a rates map. CurrencyCore moves the key into a header, puts the base in the path, and returns a dated map. ISO codes and the units-per-one-base arithmetic stay the same, so the work is mostly URL and response plumbing.

Public Open Exchange Rates pricing and coverage below were checked on 2026-11-10. Verify the vendor’s current plan before you budget.

What changes at a glance

1. Replace app_id with a bearer token

# Before
curl "https://openexchangerates.org/api/latest.json?app_id=YOUR_KEY&base=EUR"

# After
curl "https://api.currency-core.com/v1/rates/EUR" \
  -H "Authorization: Bearer cc_test_your_key"

Remove app_id from URLs, logs, and fixtures. CurrencyCore does not accept query-string auth, so there is no fallback form. Use a test key, then a live key. See Authentication.

2. Map endpoints

Open Exchange Rates returns a non-USD base on paid plans. CurrencyCore puts the base in the path on every plan, so /v1/rates/EUR is a complete snapshot with no second call.

3. Map response fields

{ "timestamp": 1762732800, "base": "USD", "rates": { "EUR": 0.8924, "INR": 94.13 } }

{ "base": "USD", "date": "2026-11-10", "rates": { "USD": 1, "EUR": 0.8924, "INR": 94.13 } }

timestamp has no equivalent. Use date, a UTC calendar date. Dated requests may also return requestedDate and asOf, showing the fixing used. base and rates map directly, and the base entry is 1.

A CurrencyCore conversion returns one entry per target:

{ "from": "USD", "amount": 100, "date": "2026-11-10", "results": [{ "to": "INR", "result": 9413, "rate": 94.13 }] }

Read results[0].result for the amount and results[0].rate for the rate. Match by results[].to when you send several targets.

4. Cut over

1. Create an organization and a cc_test_ key.
2. Change auth and URL construction in one client module.
3. Rewrite latest.json calls as /v1/rates/{base} and delete base.
4. Rewrite historical/DATE.json calls as /v1/rates/{base}?date=DATE.
5. Rewrite time-series calls as /v1/history, one currency at a time.
6. Rewrite conversion calls and read results[0].
7. Shadow production requests and compare the same dates.
8. Watch 401, 403, 429, then revoke the Open Exchange Rates app ID.

When Open Exchange Rates is the better fit

Stay if USD is your only base, you already cache the snapshot, and you do not need PPP or analytics. Its long record is a real reason to stay. If you need 30-minute or 5-minute updates, its Enterprise and Unlimited plans list those cadences and CurrencyCore does not sell them. Choose the cadence and base you actually need.

Related

• API reference
• OpenAPI specification
• Authentication
• Errors
• All guides
• Provider-neutral migration checklist