Data Methodology for Historical FX Evidence

FXpeek is built for workflows where someone asks, "Which historical exchange rate did you use, and where did it come from?"

A useful FXpeek record should keep the currency pair, date or period, reference value, source URL, retrieval context, and reference-only limitation together.

This is different from a generic converter. The goal is not to predict markets; it is to make historical reference data easier to reproduce in invoices, close files, ecommerce payout checks, spreadsheets, and lightweight internal tools.

FXpeek publishes public currency-pair, date, monthly-average, stablecoin, and scenario pages only when a page can be tied to supported data and a concrete user task.

Priority is given to pages that produce reusable outputs: a dated source URL, CSV rows, JSON API examples, Google Sheets formulas, citation text, or a small paid evidence pack.

The first coverage focuses on China, Southeast Asia, stablecoin reference, and selected long-tail currency workflows where generic FX APIs often provide data but not the reporting context.

A paid evidence pack is scoped before checkout or inside the checkout fields: currency pair, date range or month, output format, and the reporting workflow.

The normal deliverable is CSV or spreadsheet-ready data plus the source URL pattern and a short reference note that can be kept with a working paper.

For month-end or invoice workflows, FXpeek separates the document date, payment date, close date, retrieval date, and source note so a reviewer can reproduce the path later.

FXpeek avoids publishing indexable pages that cannot be backed by available data or a concrete reporting use case.

When data is older than the current day, pages should describe it as the latest available reference rate, not as live, current, or today's rate.

When coverage is incomplete, the page should say so instead of presenting a value as official, transaction-ready, or guaranteed.

FXpeek rates are reference data for lookup, reporting, research, and spreadsheet workflows.

They are not bank quotes, settlement rates, tax authority figures, accounting authority figures, investment advice, trading signals, remittance quotes, custody services, or transaction offers.

If a filing, audit, contract, or accounting policy requires a specific authority or rate source, the user remains responsible for confirming that requirement with the relevant adviser or policy owner.

Use the public pages when a single date, pair, API URL, CSV URL, or spreadsheet formula is enough.

Use FXpeek Data Services when the work needs a small evidence pack: one or more pairs, a date range, source notes, CSV rows, and a reference-only explanation that can sit beside a close file or invoice reconciliation.

FXpeek records the source path and the date attached to a reference value. This makes a row easier to review, but does not turn it into an official or executable quote.

Fiat reference-rate source

Supported fiat history is retrieved from the Frankfurter API, which publishes ECB reference-rate data where coverage is available. FXpeek keeps a data-backed historical table as a fallback for supported pages.

Stablecoin reference-rate source

USDT and USDC reference pages use the CoinGecko simple price API. These values are shown separately because stablecoin market references are not ECB fiat reference rates.

Refresh and retrieval context

Supported fiat pages request upstream updates and show the actual latest business-day date. Weekends and publication lags keep the previous available date; FXpeek does not relabel it as today's rate.

Why a bank, platform, or payment quote can differ

Reference rates do not include a provider spread, fees, liquidity, cut-off time, local settlement rules, or a contract-specific rate. FXpeek does not calculate a universal deviation from a bank or central-bank requirement; use the source required by your policy for regulated filing or settlement work.

Frankfurter API documentation · ECB euro reference exchange rates · CoinGecko