chore: move to Frankfurter API for exchange rate (#1214)

client/src/hooks/useExchangeRates.ts

@@ -2,7 +2,7 @@ import { useCallback, useEffect, useState } from 'react'
 
 /**
  * Live FX rates for the Costs panel, used to convert every amount into the user's
- * display currency. Fetches exchangerate-api.com (no key, already CSP-allowlisted
+ * display currency. Fetches api.frankfurter.dev (no key, already CSP-allowlisted
  * for the dashboard widget) for the given base and caches per base in memory +
  * localStorage for a few hours. rates[X] = units of X per 1 base, so an amount in
  * currency C converts to base as `amount / rates[C]`.
@@ -33,14 +33,19 @@ export function useExchangeRates(base: string) {
     if (cached) setRates(cached.rates)
     if (cached && Date.now() - cached.ts < TTL_MS) return
     let cancelled = false
-    fetch(`https://api.exchangerate-api.com/v4/latest/${encodeURIComponent(upper)}`)
+    fetch(`https://api.frankfurter.dev/v2/rates?base=${encodeURIComponent(upper)}`)
       .then(r => r.json())
-      .then((d: { rates?: Record<string, number> }) => {
-        if (cancelled || !d?.rates) return
-        const entry = { rates: d.rates, ts: Date.now() }
+      .then((d: Array<{ quote?: string; rate?: number }>) => {
+        if (cancelled || !Array.isArray(d)) return
+        // Frankfurter omits the base's own self-rate, so seed it with `base = 1`.
+        const rates: Record<string, number> = { [upper]: 1 }
+        for (const r of d) {
+          if (r && typeof r.quote === 'string' && typeof r.rate === 'number') rates[r.quote] = r.rate
+        }
+        const entry = { rates, ts: Date.now() }
         mem.set(upper, entry)
         try { localStorage.setItem('trek_fx_' + upper, JSON.stringify(entry)) } catch { /* ignore */ }
-        setRates(d.rates)
+        setRates(rates)
       })
       .catch(() => { /* offline → keep cached/identity */ })
     return () => { cancelled = true }

client/src/pages/DashboardPage.test.tsx

@@ -20,8 +20,11 @@ beforeEach(() => {
   } as any);
   // Intercept CurrencyWidget's external fetch so it resolves before teardown
   server.use(
-    http.get('https://api.exchangerate-api.com/v4/latest/:currency', () => {
-      return HttpResponse.json({ rates: { USD: 1.08, EUR: 1, CHF: 0.97 } });
+    http.get('https://api.frankfurter.dev/v2/rates', () => {
+      return HttpResponse.json([
+        { date: '2026-06-16', base: 'EUR', quote: 'USD', rate: 1.08 },
+        { date: '2026-06-16', base: 'EUR', quote: 'CHF', rate: 0.97 },
+      ]);
     }),
   );
 });

client/src/pages/DashboardPage.tsx

@@ -461,9 +461,15 @@ function CurrencyTool(): React.ReactElement {
   const [rates, setRates] = useState<Record<string, number> | null>(null)
 
   const fetchRate = React.useCallback(() => {
-    fetch(`https://api.exchangerate-api.com/v4/latest/${from}`)
+    fetch(`https://api.frankfurter.dev/v2/rates?base=${from}`)
       .then(r => r.json())
-      .then(d => setRates(d.rates ?? null))
+      .then((d: Array<{ quote: string; rate: number }>) => {
+        if (!Array.isArray(d)) { setRates(null); return }
+        // Frankfurter omits the base's own self-rate; seed it so `from` stays selectable.
+        const map: Record<string, number> = { [from]: 1 }
+        for (const r of d) map[r.quote] = r.rate
+        setRates(map)
+      })
       .catch(() => setRates(null))
   }, [from])
 

server/src/middleware/globalMiddleware.ts

@@ -96,7 +96,7 @@ export function applyGlobalMiddleware(
           "https://en.wikipedia.org", "https://commons.wikimedia.org",
           "https://*.basemaps.cartocdn.com", "https://*.tile.openstreetmap.org",
           "https://unpkg.com", "https://open-meteo.com", "https://api.open-meteo.com",
-          "https://geocoding-api.open-meteo.com", "https://api.exchangerate-api.com",
+          "https://geocoding-api.open-meteo.com", "https://api.frankfurter.dev",
           "https://router.project-osrm.org/route/v1/", "https://routing.openstreetmap.de/",
           "https://api.mapbox.com", "https://*.tiles.mapbox.com", "https://events.mapbox.com"
         ],

server/src/services/exchangeRateService.ts

@@ -1,7 +1,7 @@
 /**
  * Live exchange rates for the Costs/Budget money conversion.
  *
- * Fetches from exchangerate-api.com (no key, already CSP-allowlisted for the
+ * Fetches from api.frankfurter.dev (no key, already CSP-allowlisted for the
  * dashboard widget) and caches per base currency in-memory for a few hours so a
  * settlement request never hammers the upstream. Rates are "units of X per 1
  * base", so an amount in currency C converts to base as `amount / rates[C]`.
@@ -17,10 +17,17 @@ const inflight = new Map<string, Promise<Record<string, number> | null>>();
 
 async function fetchRates(base: string): Promise<Record<string, number> | null> {
   try {
-    const res = await fetch(`https://api.exchangerate-api.com/v4/latest/${encodeURIComponent(base)}`);
+    const res = await fetch(`https://api.frankfurter.dev/v2/rates?base=${encodeURIComponent(base)}`);
     if (!res.ok) return null;
-    const data = (await res.json()) as { rates?: Record<string, number> };
-    return data.rates && typeof data.rates === 'object' ? data.rates : null;
+    // Frankfurter returns an array of { date, base, quote, rate } and omits the
+    // base's own self-rate, so seed the map with `base = 1` then index by quote.
+    const data = (await res.json()) as Array<{ quote?: string; rate?: number }>;
+    if (!Array.isArray(data)) return null;
+    const rates: Record<string, number> = { [base.toUpperCase()]: 1 };
+    for (const r of data) {
+      if (r && typeof r.quote === 'string' && typeof r.rate === 'number') rates[r.quote] = r.rate;
+    }
+    return Object.keys(rates).length > 1 ? rates : null;
   } catch {
     return null;
   }

shared/package.json

@@ -51,7 +51,7 @@
   },
   "scripts": {
     "build": "tsdown",
-    "build:watch": "tsdown --watch",
+    "build:watch": "tsdown --watch --no-clean",
     "test": "vitest run",
     "test:watch": "vitest",
     "typecheck": "tsc --noEmit",

wiki/Dashboard-Widgets.md

@@ -31,7 +31,7 @@ The currency converter lets you quickly convert an amount between two currencies
 
 You can also click the swap arrow to reverse source and target.
 
-**Exchange rates** are fetched from [exchangerate-api.com](https://www.exchangerate-api.com) using the `https://api.exchangerate-api.com/v4/latest/{from}` endpoint. Rates are refreshed each time you change a currency or click the refresh icon.
+**Exchange rates** are fetched from [Frankfurter](https://frankfurter.dev) using the `https://api.frankfurter.dev/v2/rates?base={from}` endpoint. Rates are refreshed each time you change a currency or click the refresh icon.
 
 **Supported currencies:** 162 currencies are available in the selector, including all major fiat currencies (USD, EUR, GBP, JPY, etc.) and many minor ones.