Methodology
How exchange-rate data is fetched, dated, cached, calculated, reviewed and displayed.
Data source and publication date
The system retrieves daily reference rates through the Frankfurter API. Pages show the provider publication date rather than the visitor request time.
Weekends, holidays and unavailable dates
Official institutions generally publish on working days. Historical tools preserve both the requested date and the actual returned publication date and do not invent missing observations.
Caching and failure handling
Latest rates are cached for 30 minutes by default and historical data for 24 hours. Cache writes use temporary-file replacement to avoid partial files. When the provider is unavailable, the application can fall back to a previously validated cache and label the state.
Automation and editorial review
Automation handles arithmetic, page linking and structured data. Currency facts, country payment notes, guides and indexable pair pages require editorial review. A tool page can remain usable while carrying noindex until it passes the content-quality gate.
Fees and limitations
Reference rate only. Banks and payment providers may use different rates and fees.