Exchange Rate API vs Open Exchange Rates: The 2026 Comparison

Open Exchange Rates has been a staple currency API for more than a decade. It's reliable, well-documented, and the 1,000-request free tier is generous on paper. But talk to developers shipping payments, invoicing, and multi-currency checkouts in 2026 and you hear the same five complaints repeatedly: USD-only base currency on the free tier, hourly updates, no official SDKs, time-series queries burn the quota, and the conversion endpoint is paid-only.

This article compares Open Exchange Rates against Exchange Rate API across the criteria that actually matter, and explains where Exchange Rate API was built specifically to fix each of those pain points.

TL;DR — Side-by-side

Update frequency: real-time vs hourly

This is the single biggest technical difference.

• Exchange Rate API refreshes rates every 60 seconds from Reuters (Refinitiv) and interbank market feeds.
• Open Exchange Rates refreshes hourly on its free, Developer ($12/mo), and Enterprise ($47/mo) tiers. Only the Unlimited plan ($97/mo) updates every 10 minutes — and that's still not real-time.

For anything where the exchange rate affects the amount of money changing hands — checkout pricing, cross-border quotes, treasury dashboards — hourly data can be 1% off the market during a volatile session. That 1% comes out of your margin.

Base currency: USD-only is a 2012-era constraint

Open Exchange Rates' free plan only supports USD as a base currency. If you're building anything with a non-USD home market, you have two options:

1. Fetch USD-based rates and do cross-rate math in application code (extra code, rounding risk).
2. Upgrade to the Developer plan ($12/mo) or higher to get flexible base currencies.

Exchange Rate API lets you pass any base currency on any plan, including the free tier:

GET /api/v1/rates?source=EUR&target=USD,GBP,CHF

Historical data: watch the quota burn

OpenExchangeRates does include historical data on the free plan — but with a catch. The time-series.json endpoint counts one request per day of data returned. A 30-day query uses 30 of your 1,000 monthly requests. A one-year backfill (365 days) uses 36.5% of your quota in a single call.

Exchange Rate API's historical endpoint returns the entire range as one request:

GET /api/historical-rates?source=USD&target=EUR&from=2025-04-01&to=2026-04-01

Conversion: free vs paid

Open Exchange Rates exposes a dedicated /api/convert.json endpoint — but it's paid-only. On the free tier you have to fetch rates and do the multiplication in your own code.

With Exchange Rate API's official SDKs, convert() is a one-liner on every plan:

const result = await client.convert('USD', 'EUR', 1000);
// { from: 'USD', to: 'EUR', amount: 1000, rate: 0.9234, result: 923.4 }

Official SDKs

OpenExchangeRates' own documentation says it plainly: they don't maintain official SDKs. Exchange Rate API ships first-party SDKs for three languages:

• npm install @exchangerateapi/sdk (JavaScript/TypeScript)
• pip install exchangerateapi (Python)
• composer require exchangerateapi/sdk (PHP)

Plus an MCP server for AI coding tools (Claude Code, Cursor, Claude Desktop) and a DeepSeek function-calling package — integrations Open Exchange Rates doesn't ship at all.

Data source transparency

OpenExchangeRates describes its data as "blended" from multiple sources, but doesn't disclose which sources. Exchange Rate API publishes its sources: Reuters (Refinitiv) and interbank market feeds. These are the same feeds used by Bloomberg terminals and enterprise treasury systems.

When Open Exchange Rates is still the right call

• You already have a working integration and don't want to touch it.
• You need 1,000+ requests/month on a free tier and can tolerate hourly data.
• Your use case is USD-only accounting or price display where base flexibility doesn't matter.

When Exchange Rate API is the better choice

• You need real-time (60-second) rates without paying.
• You need any-base-currency flexibility on a free plan.
• You want official SDKs instead of community libraries.
• You want MCP or DeepSeek tool-calling for AI assistants.
• You need transparent data sources for compliance or audit.

Migration is a one-afternoon job

The two APIs share the same JSON shape for the core "get rates" call. In most projects, swapping the client is a handful of lines. We've written a full migration guide that covers every endpoint.

npm install @exchangerateapi/sdk