Frankfurter vs VATComply.com

Frankfurter aggregates and republishes daily reference rates from roughly 84 central banks, not solely the ECB, covering 200+ currencies with history back to 1948, and supports current, dated, and time-series conversion queries, including filtering to a specific source institution. It's free with no API key and no request quotas beyond abuse-prevention rate limiting, returns JSON by default plus CSV and streaming NDJSON, and now also ships an official self-hosting Docker image and an MCP server for AI-agent integration. The project's site and docs moved from frankfurter.app to frankfurter.dev, with the old domain now redirecting.

VATcomply bundles several EU compliance primitives behind one free, keyless API: VIES-backed VAT number validation, current VAT rates for all 27 EU member states, daily ECB foreign-exchange reference rates with history back to January 1999, IP-based geolocation, and IBAN validation. Rather than gating access behind an API key, it simply rate-limits anonymous callers, and it ships both narrative documentation on its homepage and a full interactive OpenAPI reference at a separate endpoint.