ExchangeRate-API / exchangerate.host
Provides real-time and historical foreign exchange rates, currency conversion, and supported currency lists. Covers 160+ fiat currencies with rates sourced from central banks and financial data providers. Some providers also support cryptocurrency rates.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
HTTPS enforced. API key in URL path is a weak pattern - key visible in server logs, browser history, and referrer headers. No scopes or IP restrictions. For agents, key should be kept server-side and rotated periodically. No documented security advisory process.
⚡ Reliability
Best When
An agent needs straightforward currency conversion or FX rate lookup for display, reporting, or normalization purposes and does not need bank-grade precision or executable rates.
Avoid When
You need real-time interbank rates with sub-second updates, executable FX quotes, or rates for exotic/illiquid currency pairs.
Use Cases
- • Converting prices between currencies in e-commerce or invoicing agents
- • Displaying localized pricing with real-time FX rates in multi-currency apps
- • Calculating historical exchange rates for financial reporting or audit agents
- • Monitoring FX rate changes and triggering alerts when thresholds are crossed
- • Normalizing financial data across currencies for analytics pipelines
Not For
- • Live trading or arbitrage (rates are indicative, not executable)
- • Tick-level FX data for algorithmic trading strategies
- • Options, futures, or derivative pricing
Interface
Authentication
API key passed as part of the URL path (ExchangeRate-API style: /v6/{api_key}/latest/{base}) or as a query parameter depending on provider variant. No OAuth or scopes.
Pricing
ExchangeRate-API and exchangerate.host are distinct services with similar names. Free tier sufficient for light agent usage. Historical data and some currencies require paid plans.
Agent Metadata
Known Gotchas
- ⚠ ExchangeRate-API and exchangerate.host are two different services with near-identical names - agents must be configured for the correct provider endpoint
- ⚠ Rates are updated at different frequencies per plan (hourly on free, every 60 seconds on paid) - agents needing fresh rates must check update time from response
- ⚠ API key embedded in URL path (not header) makes key rotation harder and exposes it in server access logs
- ⚠ Free plans do not include historical rates - agents querying past dates will get 403 errors without clear messaging about plan requirements
- ⚠ Base currency on free plans may be restricted to USD or EUR - cross-currency pairs require paid plan or two-step conversion
Alternatives
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Scores are editorial opinions as of 2026-03-07.