Fixer vs ExchangeRate-API: which free tier actually fits your project
Fixer caps its free plan at 100 calls a month; its public pricing matrix does not clearly state the free plan's base-currency rule. ExchangeRate-API takes a different approach entirely, splitting a keyed tier from a keyless one with its own rules. The right pick depends on what you are building, not which name sounds more established.
Fixer's free plan gives you 100 calls a month, with conversion listed as a paid-tier feature; verify the base-currency rule because the public pricing matrix is unclear. ExchangeRate-API gives you a choice: a keyed free tier at 1,500 calls a month, or a keyless endpoint that updates once a day and requires visible attribution. Neither is a strict upgrade over the other; they solve different problems. These facts were checked against Fixer's pricing and ExchangeRate-API's free-access documentation on September 1, 2026.
Two different shapes of free
Fixer's free plan is listed at 100 calls a month with hourly updates, SSL, and historical data included. Conversion is listed as a paid-tier feature. The public pricing matrix does not clearly state whether the free plan locks the base to EUR, so verify that behavior in current documentation before designing around it.
ExchangeRate-API splits its offering in a way Fixer does not: a keyed free tier at 1,500 calls a month, and a separate open-access endpoint at open.er-api.com needing no key or signup. That endpoint updates once per day rather than hourly and carries its own attribution terms, covered below.
Base currency: the constraint that decides for you
This is the point to verify before choosing. Fixer's public pricing matrix does not clearly state the free plan's base-currency rule, while ExchangeRate-API documents its free options as unrestricted by base. Check Fixer's current documentation or test a non-EUR request on your account.
Neither of ExchangeRate-API's free options restricts base currency the way Fixer does. A project quoting from USD, or built for a market where the local currency is the natural base, rules Fixer's free plan out immediately.
Conversion: built in, or do the math yourself
Fixer's free plan has no conversion endpoint. You get a table of rates and write the multiplication yourself — one line of arithmetic, but worth knowing before you go looking for a /convert call in Fixer's free docs.
Attribution and redistribution: the strings attached to "free"
Fixer's free-plan terms are the usual shape: use the data within your monthly limit, no attribution stated. ExchangeRate-API's open-access endpoint asks for more — a visible credit line and live link, plus a rule against redistributing the raw feed.
That attribution requirement is not a footnote. A backend service, an internal dashboard, or a batch job with no user interface has nowhere natural to put "Rates By Exchange Rate API." The keyed ExchangeRate-API tier and Fixer's paid tiers both drop that requirement.
What happens when you go over
ExchangeRate-API's open-access endpoint returns HTTP 429 once you exceed its rate limit, and the restriction lifts after 20 minutes — a documented, predictable window worth building retry logic around rather than guessing.
Fixer's free plan works on a hard monthly cap instead of a rolling limit. Once 100 calls are used, calls fail until the next billing cycle resets — no 20-minute cooldown, since the limit is monthly, not per-window.
Verdicts by use case
A prototype you're building over a weekend, testing a single EUR-based conversion flow: Fixer's 100 calls a month is enough to poke at the API and see the response shape. You won't run load tests, but you don't need to yet.
Once real users arrive, even a handful, 100 calls a month runs out fast. ExchangeRate-API's 1,500-call keyed tier, or its once-daily open-access endpoint if daily-only freshness works for you, both outlast Fixer's free plan here.
Where the base currency is neither USD nor EUR, verify Fixer's current free-plan behavior before committing. ExchangeRate-API documents no base restriction on either free path, making it the clearer zero-cost option on this specific requirement.
Cannot display attribution anywhere a user or operator would see it? ExchangeRate-API's open-access endpoint is disqualified by its own terms — the credit line and link are required. Its keyed 1,500-call tier drops that requirement, and so does paying for Fixer. Between those two, the choice comes down to quota and base currency again.
When neither free tier holds up
If your call volume outgrows 100 or 1,500 a month, or you need intraday updates with a documented non-EUR base, exchangerate.dev's free tier gives 10,000 calls a month with no card required and no base-currency restriction — one more option worth checking alongside Fixer's and ExchangeRate-API's paid plans.