I Built a Free Currency Converter API — No API Key, No Signup

I needed a simple exchange rate API for my currency converter project, but all the popular ones (XE, OANDA, CurrencyLayer, Fixer.io) require signup, an API key, or a credit card. Some cap you at 100 requests per month. Others return data cached yesterday. So I built my own — and made it completely public. → Try it now: currencyexchangetool.com/api-docs No signup. No API key. No monthly cap. Just make a GET request. The API provides live exchange rates for 100+ currencies, including major, emerging-market, and cross-rate pairs. Rates are fetched live from Yahoo Finance on each request — you always get the current rate, not cached data. It is rate-limited per IP (not per account): 100 requests/minute for convert and currencies, 30 requests/minute for history. There is no monthly cap and no key to manage. # Convert 100 USD to EUR GET /api/v1/convert?from=USD&to=EUR&amount=100 # List supported currencies GET /api/v1/currencies # Historical data — last N days, a single date, or a range (max 365 days) GET /api/v1/history?from=USD&to=UAH&days=7 GET /api/v1/history?from=USD&to=UAH&date=2026-05-01 GET /api/v1/history?from=USD&to=UAH&start_date=2026-04-01&end_date=2026-05-28 curl -s "https://www.currencyexchangetool.com/api/v1/convert?amount=100&from=USD&to=UAH" import requests res = requests.get( 'https://www.currencyexchangetool.com/api/v1/convert', params={'amount': 100, 'from': 'USD', 'to': 'UAH'} ) data = res.json() print(f"100 USD = {data['result']} UAH") const res = await fetch( 'https://www.currencyexchangetool.com/api/v1/convert?amount=100&from=USD&to=UAH' ); const data = await res.json(); console.log(`100 USD = ${data.result} UAH`); package main import ( "encoding/json" "fmt" "net/http" "net/url" ) func main() { params := url.Values{} params.Add("amount", "100") params.Add("from", "USD") params.Add("to", "UAH") resp, _ := http.Get( "https://www.currencyexchangetool.com/api/v1/convert?" + params.Encode(), ) defer resp.Body.Close() var data map[string]any json.NewDecoder(resp.Body).Decode(&data) fmt.Printf("100 USD = %v UAH\n", data["result"]) } <?php $response = file_get_contents( 'https://www.currencyexchangetool.com/api/v1/convert?' . http_build_query(['amount' => 100, 'from' => 'USD', 'to' => 'UAH']) ); $data = json_decode($response, true); echo "100 USD = {$data['result']} UAH"; ?> Add format=xml for Google Sheets compatibility: =VALUE(IMPORTXML( "https://www.currencyexchangetool.com/api/v1/convert?amount=1&from=USD&to=EUR&format=xml", "/response/rate" )) API API Key Signup Currencies Free Limit Updates Currency Exchange Tool ⭐ No No 100+ 100/min, no monthly cap Live Frankfurter No No ~30 (ECB) Unlimited Daily MoneyConvert No No 182+ Rate-limited 5 min ExchangeRate-API (Open) No No 160+ Rate-limited Daily ExchangeRate-API (Free) Yes Yes 160+ 1,500/mo Daily FreeCurrencyAPI Yes Yes 32 1,000/mo Daily Open Exchange Rates Yes Yes 170+ 1,000/mo Hourly Fixer.io Yes Yes 170+ 100/mo Daily CurrencyAPI.net Yes Yes 300+ 500/mo Daily Key insight: Our API is the only one that combines no API key, no signup, no monthly cap, live rates, and 100+ currencies. Prototyping: No need to stop coding and fill out a registration form Open source: You can commit working examples without exposing API keys CI/CD: No env variables to configure in every pipeline Education: Every student can follow along without their own key Hackathons: Zero setup friction — just write code All endpoints return a consistent JSON envelope (or XML with format=xml): { "success": true, "from": "USD", "to": "EUR", "amount": 100, "rate": 0.9234, "result": 92.34, "change24h": -0.0002, "changePct24h": -0.0229, "updatedAt": "2026-06-08T12:00:00.000Z" } Error responses are predictable: { "success": false, "error": "Unsupported currency", "code": "unsupported_currency" } When you exceed the rate limit you get HTTP 429 with a Retry-After header, and every response carries X-RateLimit-Limit / X-RateLimit-Remaining so you can back off early. CORS enabled — Access-Control-Allow-Origin: * on every endpoint, with OPTIONS preflight Rate limit headers — X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset XML output — format=xml for Google Sheets integration Historical data — Up to 365 days of daily rates SSL/HTTPS — Every request is encrypted Side projects & MVPs — Get building in seconds, not minutes E-commerce — Display prices in local currencies Fintech dashboards — Live rate widgets without auth complexity AI assistants — Simple REST endpoint for currency queries Google Sheets users — Pull live rates into spreadsheets Students — Learn REST API integration with a no-friction endpoint Built with Next.js API routes running on Vercel. No backend database — rates are fetched on-demand from Yahoo Finance. The main site (a currency converter) and the API share the same infrastructure, keeping operational costs near zero. The API is live and running right now: curl -s "https://www.currencyexchangetool.com/api/v1/convert?amount=1&from=USD&to=EUR" No signup, no API key — it just works. Documentation: currencyexchangetool.com/api-docs Main site: currencyexchangetool.com GitHub: github.com/Kaiukov/currency-converter-vercel Feedback welcome! Open an issue on GitHub or leave a comment below. If you find this useful, a quick star on GitHub helps others discover it.