exchangerate.devAccounting software asks different questions from a shop. It needs the rate on a past date, enough history to reach last year's books, and a way to show an auditor where a figure came from. Many tax offices also name their own rate, which no market feed replaces.
Who wrote this
We sell exchangerate.dev, so it is on this list and we know its numbers best. Every other row comes from that provider's own pages, read on 2 Nov 2026. Where the pages do not say, the table says "not stated". Each provider has a review page with its sources.
What accounting software needs
- A rate by date. An invoice dated 12 October converts at the rate of 12 October. The API has to return any past business day.
- History that reaches last year. Year-end work looks back 12 months or more.
- Traceable figures. A timestamp and a source label on each rate let you answer "where did this come from".
- Official rates. A tax return or a customs entry may require the authority's published rate. A market rate will not do. See official rate for an invoice or customs date.
- Plain licence terms. A commercial product needs terms that permit it.
Side by side
| Provider | History | Rate by date on | Source and time on each rate | Government-published rates |
|---|---|---|---|---|
| exchangerate.dev | 30 days on Free, 365 days on Basic, from 1999 on Plus and Pro | Free and above, within the history window | source, market_session and data_updated_at on responses | Yes: tax, customs and central bank tables from 24 countries, with authority and legal basis |
| Fixer | Cites 19 years; historical data listed on Free | All plans | Not stated on the pages checked | Not stated |
| Open Exchange Rates | Historical rates on every account | All plans | Not stated on the pages checked | Not stated |
| ExchangeRate-API | Over 30 years on Pro; pages disagree on Free | Pro and above per the docs | Not stated on the pages checked | Not stated |
| currencyapi | Back to 1999 on all plans | All plans | Not stated on the pages checked | Has an official-rates endpoint |
| Xe Currency Data | Back to 1998 | Not stated | Not stated on the pages checked | Not stated |
"Not stated" means the pages we read do not say. It does not mean the provider lacks the feature.
The shortlist
exchangerate.dev
Every response carries source, market_session and data_updated_at, and date responses add an is_forward_filled flag for days without a fixing. A reviewer can trace each figure. The official rates endpoints return the table a tax office or customs service publishes, the dates it covers and the legal basis. Free history is 30 days, a year on Basic ($19) and everything back to 1999 on Plus ($39). The gap: official lookups for past dates need Basic, and the convert endpoint for official rates needs Plus. See the accounting software use case and official rates.
Fixer
Fixer says it holds 19 years of data and lists historical data on the Free plan, though the free plan is for non-commercial use. Time-series needs Professional at $59.99 a month. A firm with a daily close and a single date per invoice can work with Basic at $14.99. Read the Fixer review.
Open Exchange Rates
Every account reaches historical rates, and time-series starts on the $47 Enterprise plan. VIP adds open-high-low-close prices and uptime SLA terms on request. It does not describe official or tax rates on the pages we read. Read the Open Exchange Rates review.
ExchangeRate-API
Pro at $10 a month lists over 30 years of history and updates hourly. The pages disagree on whether the free plan includes history, so ask before you build on it. It describes its rates as indicative midpoint rates unsuitable for cross-currency settlement, a statement worth reading before booking figures. Read the ExchangeRate-API review.
currencyapi
History reaches 1999 on all plans, from $9.99 a month. It has an endpoint for official rates and a cross-rate matrix for up to 25 currencies. Read the currencyapi review.
Xe Currency Data
Xe reaches back to 1998, lists SOC 2 and offers email and phone support. Core is $599 a year for 10,000 requests a month. For an accounting vendor selling to enterprises, the security attestation may settle the choice. Read the Xe review.
Pick by need
| If you need | Start with |
|---|---|
| A tax or customs authority's published rate | exchangerate.dev official rates |
| Source and timestamp on each response | exchangerate.dev |
| The longest low-cost history | currencyapi, from 1999 at $9.99 |
| A security attestation for procurement | Xe |
| Open-high-low-close prices | Open Exchange Rates VIP |
| The lowest paid price with long history | ExchangeRate-API Pro at $10, once free history is confirmed |
How we chose
We picked providers that sell a general-purpose exchange rate API and publish prices. For each, we read the pricing page, FAQ or docs and compared history, rate-by-date access, traceability and government-published rates. We did not test rival accuracy, since that needs an account with each. Our own accuracy test against the ECB reference rates is in the freshness and accuracy test.
A market-rate API gives indicative rates. When a rule names a rate, such as a customs table, use that table and keep its publication date.
Sources
Checked 2 Nov 2026. Prices and limits change, so confirm them on the provider's page before you buy.