Exchangerate Dev

exchangerate.dev API

Foreign-exchange rates over a clean REST API. 465 currency pairs across 31 currencies; actively-traded currencies reprice live (~60 s) on trading days, with ECB/FRED daily reference rates filling the rest. Every response labels its own freshness (source, market_session) per currency, so you never have to guess whether a rate is current — don't hardcode which currencies are live; the sources map tells you per call.

Base URL: https://api.exchangerate.dev

Auth — start keyless, add a key for volume

Data endpoints need no API key. Anonymous calls are served at the Free tier's rate limit (12 req/min, per IP). Just call it:

curl "https://api.exchangerate.dev/v1/latest?base=USD&symbols=EUR,JPY"

For more volume, get a free key (10,000 calls/month, no credit card) at https://exchangerate.dev/signup and send it as a Bearer token:

curl "https://api.exchangerate.dev/v1/latest?base=USD" \
  -H "Authorization: Bearer $EXCHANGERATE_API_KEY"

Store the key in the EXCHANGERATE_API_KEY environment variable — never hard-code it or pass it on a command line that lands in shell history. Rate-limit state is visible on every response via x-ratelimit-limit, x-ratelimit-remaining, and x-ratelimit-reset headers; back off when remaining hits 0 rather than retrying blind.

Endpoints

Latest rates — GET /v1/latest

curl "https://api.exchangerate.dev/v1/latest?base=EUR&symbols=USD,JPY,IDR"

{
  "result": "success",
  "base": "EUR",
  "source": "live",
  "sources": { "USD": "live", "JPY": "live", "IDR": "live" },
  "market_session": "open",
  "timestamp": "2026-07-06T10:41:30Z",
  "data_updated_at": "2026-07-06T10:41:09Z",
  "rates": { "USD": 1.14192, "JPY": 185.366, "IDR": 20512.88 },
  "derived_symbols": [],
  "notice": "Indicative rates, not for settlement."
}

GET /v1/latest/USD (base in the path) works too, as does the Frankfurter-style parameter set — code written against Frankfurter runs unchanged against this endpoint. Omit symbols to get all supported quote currencies.

Convert — GET /v1/convert/{FROM}/{TO}/{AMOUNT}

curl "https://api.exchangerate.dev/v1/convert/EUR/USD/100"

{
  "result": "success",
  "from": "EUR", "to": "USD", "amount": 100.0,
  "rate": 1.14192, "converted": 114.19,
  "derived": false, "derivation_bps_max": null,
  "source": "live", "market_session": "open",
  "timestamp": "2026-07-06T10:41:29Z"
}

converted is already rounded to the target currency's minor units — prefer it over multiplying rate yourself and re-rounding.

Batch convert — POST /v1/convert

One from currency, many targets. Each pair is metered as one call.

curl -X POST "https://api.exchangerate.dev/v1/convert" \
  -H "Content-Type: application/json" \
  -d '{"from": "USD", "pairs": [["EUR", 100], ["GBP", 50], ["JPY", 1000]]}'

The body shape is {"from": string, "pairs": [[symbol, amount], ...]} — an array of two-element tuples, not an array of objects. Response carries a conversions array with to, amount, rate, converted, derived per pair.

Single pair by slug — GET /v1/rate/{slug}

curl "https://api.exchangerate.dev/v1/rate/eur-usd"

Returns pair, base, quote, rate plus the standard freshness fields. Slug is case-insensitive (eur-usd); unknown pairs return code: "invalid_pair".

Historical snapshot — GET /v1/{YYYY-MM-DD}?base=...&symbols=...

Daily series back to 1999-01-04.

curl "https://api.exchangerate.dev/v1/2024-01-15?base=USD&symbols=EUR,JPY"

Weekend/holiday dates return the most recent business-day fix with "is_forward_filled": true. Always check that flag when the exact date matters (accounting, audits) — see the fx-rates-correctness skill for the full pitfall list.

Time-series — GET /v1/range

curl "https://api.exchangerate.dev/v1/range?base=USD&symbols=EUR&start_date=2024-01-01&end_date=2024-06-30"

Parameters are start_date / end_date (not start/end). Returns one row per business day (weekends are absent, not null). Max 366 rows per page; when has_more is true, pass next_cursor to get the next page — don't assume one page covers the whole range.

Currency metadata — GET /v1/currencies

{ "code": "AUD", "name": "Australian Dollar", "type": "fiat", "decimals": 5, "minor_units": 2, "is_derived": false }

Call this first when you need valid codes, per-pair decimal precision (decimals = quote precision, minor_units = cash rounding), or to filter out triangulated pairs.

Reading the freshness fields (the part most integrations get wrong)

Every response self-describes its freshness. Inspect these before presenting a rate as "current":

• source — the least-fresh tier across returned rates: live (~60 s intraday), ecb_daily (ECB fix, ~16:00 CET business days), fred_daily (FRED reference).
• sources — per-currency map; a mixed request can be live for EUR and ecb_daily for MYR.
• market_session — open, weekend, or interbank_closed. source: live + market_session: weekend means the value is the last trading-week consensus, not a fresh quote. Say so in any UI or answer.
• data_updated_at — when the pipeline last wrote the value; timestamp — when the response was produced.
• derived_symbols / derived: true — the pair was triangulated through USD (error ≈ 1–2 bps, bounded by derivation_bps_max). Filter these out for research that needs native quotes.

All rates are indicative (aggregated market data, ~5–15 bps) — fine for display, dashboards, analytics, and internal tooling; not for settlement or as a regulated source of record.

MCP server (for agent hosts)

Five tools — list_currencies, get_rate, convert, get_range, search_docs — on every plan including Free. HTTP endpoint: https://api.exchangerate.dev/v1/mcp/, or stdio:

{
  "mcpServers": {
    "exchangerate": {
      "command": "npx",
      "args": ["exchangerate-dev-mcp"],
      "env": { "EXCHANGERATE_API_KEY": "YOUR_KEY" }
    }
  }
}

Prefer the MCP server when the host supports it (Claude Desktop/Code, Cursor); use REST when writing application code. Source: https://github.com/nusantara-ventures/exchangerate-dev-mcp

Error handling

Errors return {"result": "error", "code": "...", "message": "..."} with a stable code (missing_parameter, invalid_request, invalid_pair, ...). Branch on code, not on message text. HTTP 429 = rate limited; respect x-ratelimit-reset (unix seconds) before retrying.

Related skills in this repo

• fx-rates-correctness — weekend gaps, forward-fill, precision, triangulation: the correctness pitfalls.
• multi-currency-pricing — adding multi-currency display prices to an app.
• portfolio-currency-translation — translating multi-market portfolios into one home currency.
• fx-accounting-rates — rate-of-record choices for invoicing and bookkeeping.
• fx-dashboard-widgets — live rate tickers, charts, and session-aware UI.