Data sources
YIMHO uses APIs and open datasets as data sources. The website adds converters, comparisons, charts, explanations, and academic utilities on top.
Frankfurter
Used for: Exchange rates and historical currency series
License / terms: API software MIT; underlying rates from central banks (ECB and others). Attribution required. Rates are indicative, not for transactional settlement.
Commercial use: Permitted, subject to each central-bank provider’s terms. YIMHO uses blended public reference rates with ECB as a documented source.
Attribution: Exchange rates via Frankfurter (frankfurter.dev), sourced from the European Central Bank and other official providers.
Cache: 4 hours
Open ExchangeRate-API (fallback)
Used for: Fallback latest rates if Frankfurter is unavailable
License / terms: Open Access endpoint; attribution required.
Commercial use: Permitted on the Open Access endpoint with attribution. Do not scrape paid endpoints.
Attribution: Fallback rates by ExchangeRate-API.com
Cache: 4 hours
world-countries (mledoze)
Used for: Country names, capitals, ISO codes, currencies, languages, borders, flags metadata
License / terms: MIT License
Commercial use: Yes
Attribution: Country reference data based on the world-countries dataset (MIT).
Cache: Shipped locally; refreshed when the dataset is updated.
World Bank Open Data
Used for: Population, GDP, GDP per capita, inflation, unemployment, internet usage, life expectancy
License / terms: CC BY 4.0
Commercial use: Yes, with attribution
Attribution: World Bank Open Data (data.worldbank.org), CC BY 4.0.
Cache: 24 hours
Flagcdn
Used for: Country flag images
License / terms: National flags are generally not subject to copyright; CDN terms apply.
Commercial use: Yes for flag images as commonly published public-domain / official symbols
Attribution: Flag images served via Flagcdn.
Cache: Browser cache
Crossref REST API
Used for: DOI lookup, bibliographic metadata, citation generation, paper search
License / terms: Metadata is generally available for reuse; abstracts may be publisher-restricted and are shown only when provided by Crossref.
Commercial use: Metadata reuse is expected with polite pool identification (User-Agent + mailto).
Attribution: Bibliographic metadata from Crossref.
Cache: 6 hours
OpenAlex
Used for: Works, authors, institutions, citation counts, topics, open-access flags
License / terms: Data CC0. Hosted API may require a key and has usage allowances.
Commercial use: Data is CC0. Prefer an API key in production; cache aggressively.
Attribution: Additional scholarly metadata from OpenAlex (CC0).
Cache: 6 hours