Japanese yen (JPY) exchange rate API

The yen is one of the most traded currencies in the world, and USD/JPY is one of the major pairs. It is also often described as a funding and safe-haven currency, which is why it can move sharply when global markets are stressed. For developers the yen has a quirk that breaks naive code: amounts have no decimal places, while rates expressed per 1 yen are tiny. The fxapi JPY exchange rate API returns full-precision rates either way – you decide where to round.

JPY facts for developers

• Where it’s used: Japan.
• Symbol and formatting: ¥ before the amount, comma thousands separator, no decimals: ¥12,800. In Japanese text the kanji 円 usually follows the number (12,800円). Because ¥ is shared with the Chinese yuan, use JP¥ or JPY in multi-currency UIs.
• Minor unit: 0 decimals. The sen is not used in everyday transactions.
• Central bank: the Bank of Japan. Currency interventions are decided by Japan’s Ministry of Finance and executed by the Bank of Japan.
• Regime: free float, with occasional intervention.
• Events in the historical data: after the Tōhoku earthquake in March 2011 the yen surged to a then-record high against the dollar, and the G7 intervened jointly on 18 March 2011 – the sample date on this page. The yen weakened substantially from late 2012 under “Abenomics”. The Bank of Japan kept a negative policy rate from 2016 until March 2024, and Japan intervened to support the yen in 2022 and 2024.

Get JPY rates with the fxapi API

/v1/latest and /v1/historical are available on every plan. This Go program fetches rates with base_currency=JPY and converts a whole-yen price, also printing the “per 100 yen” view many finance teams prefer:

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
)

type latestResponse struct {
	Data map[string]struct {
		Code  string  `json:"code"`
		Value float64 `json:"value"`
	} `json:"data"`
}

func main() {
	req, err := http.NewRequest("GET",
		"https://api.fxapi.com/v1/latest?base_currency=JPY&currencies=USD,EUR,GBP", nil)
	if err != nil {
		log.Fatal(err)
	}
	req.Header.Set("apikey", os.Getenv("FXAPI_KEY"))

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		log.Fatalf("fxapi returned %s", resp.Status)
	}

	var out latestResponse
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		log.Fatal(err)
	}

	const priceJPY = 12800 // yen amounts are whole numbers
	for code, r := range out.Data {
		fmt.Printf("¥%d = %.2f %s   (100 JPY = %.4f %s)\n",
			priceJPY, priceJPY*r.Value, code, 100*r.Value, code)
	}
}

See the Go guide for caching and error handling, and the historical exchange rates API for back-dated values such as the 2011 intervention. The South Korean won and the Chinese yuan pages cover the other major East Asian currencies.

Things to watch

• Never store yen with two decimals in a column that also feeds payment providers – many reject fractional JPY amounts.
• Precision on inverse rates. Rounding USD-per-yen to 4 decimals destroys most of the information; store the full value. See currency rounding and precision.
• Intervention days can produce large daily moves; validate against a tolerance rather than a fixed band.

Popular JPY pairs

Request any of these pairs – or any other combination of the 190+ supported currencies – with base_currency=JPY:

Monthly averages and fluctuation for JPY

# Monthly average JPY rates for 2025 (IAS 21 / ASC 830)
curl -G "https://api.fxapi.com/v1/average" \
  -d date_from=2025-01-01 -d date_to=2025-12-31 -d period=month \
  -d base_currency=JPY -d currencies=USD,EUR,GBP \
  -H "apikey: $FXAPI_KEY"

# How did JPY move over the last year?
curl -G "https://api.fxapi.com/v1/fluctuation" \
  -d date_from=2025-10-01 -d date_to=2026-10-01 \
  -d base_currency=JPY -d currencies=USD,EUR,GBP \
  -H "apikey: $FXAPI_KEY"

See the historical exchange rates API, average rates API and documentation for every parameter.

JPY is one of 190+ currencies in fxapi, the foreign exchange rates API for developers – live rates, daily history since 1999 and monthly averages with one API key.

Frequently asked questions