Data Sources and Methodology

Last updated: 2026-09-04

Most tools on 4Dev.net are purely computational - a format converter, hash function, or calculator runs entirely on data you provide, with no external data source involved (for example, JSON/XML/CSV conversion, hashing, number-base conversion, and case conversion). This page covers the tools that do depend on external data.

1. Currency and Cryptocurrency Rates

The currency converter uses two data sources:

  • Major currencies (the roughly 31 currencies the European Central Bank publishes daily reference rates for, including USD, EUR, GBP, JPY, and other widely-traded currencies): sourced from the Frankfurter data service, which republishes the ECB's own daily reference rates. Updated once per ECB business day.
  • All other currencies, plus cryptocurrencies: sourced from the fawazahmed0/currency-api open dataset, an aggregated, openly published feed updated daily, served via jsDelivr with a Cloudflare Pages fallback.

Every currency conversion result on the Website shows the timestamp of the data actually used to compute it.

2. Flag and Cryptocurrency Icons

Flag images are served from flagcdn.com. Cryptocurrency icons are served from CoinCap. Where an icon fails to load, a generic placeholder icon is shown instead - see the Accessibility Statement for why this matters for assistive technology too.

3. Independent Benchmarks

For major-currency rates, you can independently cross-check the numbers shown here against the official sources directly:

These three institutions are cited as independent public benchmarks you can compare against - not as the direct data engine 4Dev.net calls for every currency shown.

4. Developer Libraries

Some conversion features (XML parsing, spreadsheet reading/writing, Word document generation, SQL formatting) run in your browser using open-source JavaScript libraries loaded from public CDNs (cdnjs.cloudflare.com, cdn.jsdelivr.net, cdn.sheetjs.com). These process your input locally in your browser for certain instant-preview features; server-side conversion uses server-side equivalents of the same libraries. See the Third-Party Services and Advertising Disclosure page for the complete list.

5. No Warranty

This page describes methodology, not a guarantee of accuracy. See the General Disclaimer and Financial and Currency Disclaimer.