You need to split a bill in a foreign currency. You open a free currency converter. It errors out, or worse — shows you yesterday's rate. I've been there. That's why I built a currency tool that prioritizes reliability over everything else.
The rate limit problem nobody talks about
Most free currency APIs share a fatal flaw: they have rate limits that don't tell you when you've hit them. You get a stale or null response and never know why.
The common culprits:
- exchangerate-api.com — free tier is 1,500 requests/month, no burst allowed
- openexchangerates.org — free tier is 1,000 requests/month, deprecated endpoint
- frankfurter.app — genuinely free and open, but no historical data on free tier and updates only once per day
- exchangerate.host — the one I use for the everydaytoolshub converter, supports both live and historical, but rate limits apply
The pattern: the moment your tool gets any meaningful traffic, the free API tier starts returning errors or stale data. Your users get wrong rates. You don't find out until someone complains.
The EUR/USD gap that costs freelancers money
If you're a freelancer billing in EUR to US clients paying in USD, the spread between the rate you get and the rate you charge matters. At $10,000 a month, a 0.5% difference in rate is $50 lost to float.
The standard free converters aren't built for this. They're either:
- One-way — you can convert USD to EUR but not EUR to USD with the same precision
- Delayed — rates update once daily, not on every request
- Snapshot-only — they give you a rate but no historical context to know if you're getting a good time to invoice
What I built around the EUR/NOK and GBP/NOK pairs
Since the audience for everydaytoolshub skews Norwegian and European, I optimized the currency tool for the pairs that most tools under-serve:
- EUR/NOK — updated live
- GBP/NOK — updated live
- USD/EUR — updated live
- USD/GBP — updated live
The mid-market exchange rate is used as the base, so you always see the honest interbank rate before margins are added. What you see is approximately what your bank would give you, minus their spread.
The technical constraint that forces good UX
The API I use (exchangerate.host) supports ~150 currencies but updates on a schedule that means some exotic pairs (think: Nepalese rupee, Cuban convertible peso) may lag 24 hours on the free tier.
Rather than hide this, I built a last-updated timestamp directly into the tool UI. If the rate is stale, you know. That's better than silently using a wrong rate for a currency nobody checks every day.
What makes a currency tool actually useful
After iterating on this for a while, the features that matter most aren't exotic — they're the basics done well:
- Live rates — not cached for hours
- Swap button — flip FROM and TO with one tap
- Mid-market rate — no hidden margin baked in
- Mobile-friendly — most people check currency on their phone
- Copy result — one tap to copy the converted number
I added all five to the converter. Nothing revolutionary, but surprisingly few free tools have all of them without requiring an account.
→ Currency Converter — Live rates, no account
The tool covers 150+ currencies including the exotic ones, with a swap button and copy-to-clipboard. If the rate for a given pair is stale (rare, but happens with very low-volume currencies), it shows you exactly when it was last updated.
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