GET /v1/fx/time_series

GET /v1/fx/time_series

Returns recent and historical FX rates for one or more currency pairs. The endpoint is intended for currency conversion in portfolio totals and multi-currency reports.

Request

GET /v1/fx/time_series?pair=USD/EUR HTTP/1.1
Host: api.oneapi.finance
Authorization: Bearer oa_live_<your_key>

Query parameters

Param	Type	Required	Notes
`pair`	string	one of	Single pair, e.g. `USD/EUR`. The slash is significant.
`pairs`	string	one of	Comma-separated pairs, max 10. e.g. `USD/EUR,GBP/JPY`.
`start_date`	ISO date	no	Inclusive lower bound.
`end_date`	ISO date	no	Inclusive upper bound. Default now.
`outputsize`	int	no	Default 30. Cap 5,000.

Response

{
  "rates": {
    "USD/EUR": {
      "pair": "USD/EUR",
      "current": 0.9241,
      "previous": 0.9215,
      "history": [
        { "datetime": "2026-05-02T00:00:00Z", "open": 0.9215, "high": 0.9251, "low": 0.9202, "close": 0.9241 },
        { "datetime": "2026-05-01T00:00:00Z", "open": 0.9201, "high": 0.9226, "low": 0.9189, "close": 0.9215 }
      ]
    }
  }
}

Field reference

Top level:

Field	Type	Notes
`rates`	object	Map of pair to per-pair object.

Per-pair object:

Field	Type	Notes
`pair`	string	Echo of the request.
`current`	number \| null	Most recent close rate.
`previous`	number \| null	Close rate from the prior day.
`history`	array \| null	Daily OHLC bars, descending. Null if you did not request a window.

History entry:

Field	Type	Notes
`datetime`	string	ISO 8601 UTC.
`open`	number \| null
`high`	number \| null
`low`	number \| null
`close`	number \| null

The wire-format model is oneapi_core.responses.fx.FxResponse.

What “rate” means

USD/EUR is the price of 1 USD in EUR. To convert a USD amount to EUR, multiply by the rate. To convert EUR to USD, divide.

amount_eur = amount_usd * rates["USD/EUR"]["current"]
amount_usd = amount_eur / rates["USD/EUR"]["current"]

We always quote BASE/QUOTE directly. The reverse direction (EUR/USD) is a separate pair you can also request, but using 1 / rate of the forward pair gives the same answer to ~5 decimal places.

Examples

# Current rate only
curl -H "Authorization: Bearer oa_live_..." \
  "https://api.oneapi.finance/v1/fx/time_series?pair=USD/EUR&outputsize=1"

# 90 days of history for two pairs
curl -H "Authorization: Bearer oa_live_..." \
  "https://api.oneapi.finance/v1/fx/time_series?pairs=USD/EUR,GBP/JPY&outputsize=90"

import httpx, os

def convert(amount: float, base: str, quote: str) -> float:
    r = httpx.get(
        "https://api.oneapi.finance/v1/fx/time_series",
        params={"pair": f"{base}/{quote}", "outputsize": 1},
        headers={"Authorization": f"Bearer {os.environ['ONEAPI_KEY']}"},
        timeout=10.0,
    )
    r.raise_for_status()
    rate = r.json()["rates"][f"{base}/{quote}"]["current"]
    return amount * rate

print(f"100 USD = {convert(100, 'USD', 'EUR'):.2f} EUR")

async function convert(amount, base, quote) {
  const r = await fetch(
    `https://api.oneapi.finance/v1/fx/time_series?pair=${base}/${quote}&outputsize=1`,
    { headers: { Authorization: `Bearer ${process.env.ONEAPI_KEY}` } },
  );
  const body = await r.json();
  const rate = body.rates[`${base}/${quote}`].current;
  return amount * rate;
}

Errors

Status	`code`	When
400	`bad_request`	Malformed pair (missing slash), or both `pair` and `pairs`.
401	`unauthenticated`	Missing or invalid API key.
404	`not_found`	Pair not supported.
429	`rate_limit`	See rate limits.