Real-Time Forex Data API: A Developer’s Guide to Building Currency Applications

Ask any developer who has tried to build a production forex application and they’ll tell you the same thing: finding a reliable, low-latency price feed is the hardest part of the whole project — not the trading logic, not the UI, not the infrastructure. The data.

The forex market is the largest and most liquid financial market on earth, with over $7.5 trillion changing hands every single day. And yet, for developers, it’s strangely difficult to tap into. There’s no central exchange, no single source of truth. Prices are generated by a decentralized web of banks, brokers, and market makers, all operating in different time zones with overlapping sessions.

The result is a market where every data vendor is aggregating from a slightly different set of sources — and the quality gap between a premium feed and a free one is enormous.

Why Free Forex APIs Fall Short

If you’ve built anything with forex data before, you’ve probably run into the usual suspects: Yahoo Finance, Open Exchange Rates, maybe some obscure REST endpoint you found on GitHub. These work fine for displaying a rough estimate of the EUR/USD rate on a blog widget, but the moment you need sub-second updates for a trading system or a real-time dashboard, they fall apart.

The problems are predictable:

Delays that kill trading logic. Most free forex sources carry a 15-to-30-minute lag. That’s fine for currency conversion calculators, but it’s completely unusable for anything that actually executes on price.

Rate limits that punish real usage. Free tiers typically cap you at a few hundred requests per day. If you’re running a dashboard that refreshes every few seconds across multiple currency pairs, you’ll burn through your quota before the morning session ends.

No WebSocket support. Free APIs are almost always polling-based. You request, they respond. For a fast-moving market like forex, this means you’re always looking at stale data.

Data consistency issues. Different free sources often disagree on the same rate by a few pips. This might sound trivial, but pips matter — they’re the unit of measurement for forex profits and losses.

The Cost of Going Professional

On the other end of the spectrum, enterprise-grade forex data from providers like Bloomberg or Refinitiv comes with enterprise-grade pricing. Typical annual costs for a full institutional forex feed can run anywhere from $10,000 to well over $100,000 per year, depending on the coverage and update frequency you need. These products are designed for hedge funds and large banks, not for a startup trying to build a forex alert app or an indie developer writing a currency overlay for a travel platform.

There’s a growing middle ground, though. A new generation of financial data APIs — Infoway API among them — has emerged to serve developers and smaller teams who need professional-quality data without the Bloomberg price tag.

Infoway API Forex Coverage

Infoway API aggregates price data from major market makers and delivers it through a unified REST and WebSocket interface. For forex, this means genuine real-time rates with latency consistently under 100ms and an SLA of 99.6% uptime.

Our forex feed covers 85 currency pairs across all major and several exotic pairs. The list below shows only a subset of the available symbols. You can retrieve the complete list via API or download the full list in Excel format from our official website.

Beyond forex, the same API key gives you access to equities (US, HK, China A-shares, Japan, India), crypto, commodities, precious metals, and CFDs — all through the same interface. If your application eventually grows to cover more than just currencies, you won’t need to stitch together multiple providers.

Getting Started

Sign up at the Infoway website to get your API key. New accounts automatically receive a 7-day trial — no credit card required, no identity verification. Your key shows up in the dashboard immediately, and you can start making requests within minutes.

Every request needs the API key passed as a request header:

apiKey: YOUR_API_KEY_HERE

apiKey: YOUR_API_KEY_HERE

REST API Examples

The forex endpoints use the /common/ path prefix. Here’s how to pull data for the most common use cases.

Latest Trade Price

The trade endpoint returns the most recent transaction for one or more currency pairs.

import requests

url = "https://data.infoway.io/common/batch_trade/EURUSD,GBPUSD,USDJPY"

headers = {
    "User-Agent": "Mozilla/5.0",
    "Accept": "application/json",
    "apiKey": "YOUR_API_KEY_HERE"
}

response = requests.get(url, headers=headers)
print(response.json())

import requests

url = "https://data.infoway.io/common/batch_trade/EURUSD,GBPUSD,USDJPY"

headers = {
    "User-Agent": "Mozilla/5.0",
    "Accept": "application/json",
    "apiKey": "YOUR_API_KEY_HERE"
}

response = requests.get(url, headers=headers)
print(response.json())

Response:

{
  "ret": 200,
  "msg": "success",
  "traceId": "a1b2c3d4-1234-5678-abcd-ef0123456789",
  "data": [
    {
      "s": "EURUSD",
      "t": 1781672609412,
      "p": "1.08423",
      "v": "1.0",
      "vw": "1.08423",
      "td": 1
    },
    {
      "s": "GBPUSD",
      "t": 1781672609318,
      "p": "1.27185",
      "v": "1.0",
      "vw": "1.27185",
      "td": 2
    },
    {
      "s": "USDJPY",
      "t": 1781672609501,
      "p": "149.832",
      "v": "1.0",
      "vw": "149.832",
      "td": 0
    }
  ]
}

{
  "ret": 200,
  "msg": "success",
  "traceId": "a1b2c3d4-1234-5678-abcd-ef0123456789",
  "data": [
    {
      "s": "EURUSD",
      "t": 1781672609412,
      "p": "1.08423",
      "v": "1.0",
      "vw": "1.08423",
      "td": 1
    },
    {
      "s": "GBPUSD",
      "t": 1781672609318,
      "p": "1.27185",
      "v": "1.0",
      "vw": "1.27185",
      "td": 2
    },
    {
      "s": "USDJPY",
      "t": 1781672609501,
      "p": "149.832",
      "v": "1.0",
      "vw": "149.832",
      "td": 0
    }
  ]
}

You can query up to 100 symbols in a single request by comma-separating them in the URL path.

Candlestick / OHLCV Data

The candle endpoint supports 12 timeframes from 1-minute to yearly. It uses a POST request with a JSON body.

import requests
import json

url = "https://data.infoway.io/common/v2/batch_kline"

headers = {
    "User-Agent": "Mozilla/5.0",
    "Accept": "application/json",
    "Content-Type": "application/json",
    "apiKey": "YOUR_API_KEY_HERE"
}

payload = {
    "klineType": 1,      # 1 = 1-min, 2 = 5-min, 5 = 1-hour, 8 = daily
    "klineNum": 20,      # Number of candles to return (max 500 per symbol)
    "codes": "EURUSD,GBPUSD"
}

response = requests.post(url, headers=headers, data=json.dumps(payload))
print(response.json())

import requests
import json

url = "https://data.infoway.io/common/v2/batch_kline"

headers = {
    "User-Agent": "Mozilla/5.0",
    "Accept": "application/json",
    "Content-Type": "application/json",
    "apiKey": "YOUR_API_KEY_HERE"
}

payload = {
    "klineType": 1,      # 1 = 1-min, 2 = 5-min, 5 = 1-hour, 8 = daily
    "klineNum": 20,      # Number of candles to return (max 500 per symbol)
    "codes": "EURUSD,GBPUSD"
}

response = requests.post(url, headers=headers, data=json.dumps(payload))
print(response.json())

Response:

{
  "ret": 200,
  "msg": "success",
  "traceId": "b2c3d4e5-2345-6789-bcde-f01234567890",
  "data": [
    {
      "s": "EURUSD",
      "respList": [
        {
          "t": "1781671920",
          "o": "1.08401",
          "h": "1.08435",
          "l": "1.08398",
          "c": "1.08423",
          "v": "142.0",
          "vw": "154.08",
          "pc": "0.02%",
          "pca": "0.00022"
        }
      ]
    }
  ]
}

{
  "ret": 200,
  "msg": "success",
  "traceId": "b2c3d4e5-2345-6789-bcde-f01234567890",
  "data": [
    {
      "s": "EURUSD",
      "respList": [
        {
          "t": "1781671920",
          "o": "1.08401",
          "h": "1.08435",
          "l": "1.08398",
          "c": "1.08423",
          "v": "142.0",
          "vw": "154.08",
          "pc": "0.02%",
          "pca": "0.00022"
        }
      ]
    }
  ]
}

To pull historical candles, add a timestamp field to the request body. The API will return candles going back from that Unix timestamp:

payload = {
    "klineType": 8,           # Daily candles
    "klineNum": 500,
    "codes": "EURUSD",
    "timestamp": 1770000000   # Pull up to 500 daily candles ending at this time
}

payload = {
    "klineType": 8,           # Daily candles
    "klineNum": 500,
    "codes": "EURUSD",
    "timestamp": 1770000000   # Pull up to 500 daily candles ending at this time
}

Minute-level history goes back 3 years. Daily and above have no lookback restriction.

Order Book (Bid/Ask)

The depth endpoint returns the current best bid and ask for one or more pairs.

import requests

url = "https://data.infoway.io/common/batch_depth/EURUSD,USDJPY"

headers = {
    "User-Agent": "Mozilla/5.0",
    "Accept": "application/json",
    "apiKey": "YOUR_API_KEY_HERE"
}

response = requests.get(url, headers=headers)
print(response.json())

import requests

url = "https://data.infoway.io/common/batch_depth/EURUSD,USDJPY"

headers = {
    "User-Agent": "Mozilla/5.0",
    "Accept": "application/json",
    "apiKey": "YOUR_API_KEY_HERE"
}

response = requests.get(url, headers=headers)
print(response.json())

Response:

{
  "ret": 200,
  "msg": "success",
  "traceId": "c3d4e5f6-3456-7890-cdef-012345678901",
  "data": [
    {
      "s": "EURUSD",
      "t": 1781672693007,
      "a": [
        ["1.08431"],
        ["0.0"]
      ],
      "b": [
        ["1.08415"],
        ["0.0"]
      ]
    }
  ]
}

{
  "ret": 200,
  "msg": "success",
  "traceId": "c3d4e5f6-3456-7890-cdef-012345678901",
  "data": [
    {
      "s": "EURUSD",
      "t": 1781672693007,
      "a": [
        ["1.08431"],
        ["0.0"]
      ],
      "b": [
        ["1.08415"],
        ["0.0"]
      ]
    }
  ]
}

a is the ask (sell side), b is the bid (buy side). Each contains a price array and a volume array, matched by index position.

WebSocket for Real-Time Streaming

REST polling works well for dashboards that refresh every few seconds, but if you’re building something that needs to react to price moves in real time — an alert system, an automated strategy, a trading terminal — you want a persistent WebSocket connection instead.

The forex WebSocket API (and all common-type products like commodities and precious metals) is:

wss://data.infoway.io/ws?business=common&apikey=YOUR_API_KEY_HERE

wss://data.infoway.io/ws?business=common&apikey=YOUR_API_KEY_HERE

Once connected, the server pushes updates to you as they happen. No polling, no repeated round trips.

Here’s a production-ready Python client that subscribes to live trades, order book updates, and 1-minute candles for a set of forex pairs, with automatic reconnection on disconnect:

import asyncio
import json
import uuid
import logging
from typing import Optional
import websockets
from websockets.exceptions import ConnectionClosed

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s %(levelname)s %(message)s"
)
logger = logging.getLogger("forex-ws")

PAIRS = "EURUSD,GBPUSD,USDJPY,AUDUSD,USDCAD"

class ForexWebSocketClient:
    """Real-time forex streaming client with auto-reconnect."""

    def __init__(self, api_key: str):
        self.url = f"wss://data.infoway.io/ws?business=common&apikey={api_key}"
        self.ws: Optional[websockets.WebSocketClientProtocol] = None
        self.running = True
        self.reconnect_base = 5
        self.reconnect_max = 60
        self.heartbeat_interval = 30
        self._heartbeat_task: Optional[asyncio.Task] = None

    def _trace(self) -> str:
        return str(uuid.uuid4())

    async def _send(self, msg: dict) -> None:
        if self.ws:
            await self.ws.send(json.dumps(msg))

    async def _subscribe(self) -> None:
        # Subscribe to live trades
        await self._send({
            "code": 10000,
            "trace": self._trace(),
            "data": {"codes": PAIRS}
        })
        await asyncio.sleep(5)

        # Subscribe to order book
        await self._send({
            "code": 10003,
            "trace": self._trace(),
            "data": {"codes": PAIRS}
        })
        await asyncio.sleep(5)

        # Subscribe to 1-minute candles
        await self._send({
            "code": 10006,
            "trace": self._trace(),
            "data": {
                "arr": [{"type": 1, "codes": PAIRS}]
            }
        })
        logger.info("Subscribed to %s", PAIRS)

    def _start_heartbeat(self) -> None:
        if self._heartbeat_task and not self._heartbeat_task.done():
            self._heartbeat_task.cancel()

        async def beat():
            while True:
                await asyncio.sleep(self.heartbeat_interval)
                if not self.ws or self.ws.close_code is not None:
                    break
                try:
                    await self._send({"code": 10010, "trace": self._trace()})
                    logger.debug("Heartbeat sent")
                except Exception:
                    break

        self._heartbeat_task = asyncio.create_task(beat())

    def _handle(self, raw: str) -> None:
        try:
            msg = json.loads(raw)
        except json.JSONDecodeError:
            logger.error("Bad message: %s", raw)
            return

        code = msg.get("code")
        data = msg.get("data", {})

        if code == 10002:       # Trade push
            logger.info("Trade  %s @ %s", data.get("s"), data.get("p"))
        elif code == 10005:     # Depth push
            logger.info("Depth  %s bid=%s ask=%s",
                        data.get("s"),
                        data.get("b", [[None]])[0][0],
                        data.get("a", [[None]])[0][0])
        elif code == 10008:     # Candle push
            logger.info("Candle %s o=%s h=%s l=%s c=%s",
                        data.get("s"), data.get("o"),
                        data.get("h"), data.get("l"), data.get("c"))
        elif code == 10010:
            logger.debug("Heartbeat ack")
        elif code in (10001, 10004, 10007):
            logger.info("Subscription confirmed (code=%s)", code)
        else:
            logger.debug("Message: %s", raw)

    async def _connect_once(self) -> None:
        async with websockets.connect(self.url) as ws:
            self.ws = ws
            logger.info("Connected to %s", self.url)
            await self._subscribe()
            self._start_heartbeat()
            try:
                async for message in ws:
                    self._handle(message)
            finally:
                if self._heartbeat_task:
                    self._heartbeat_task.cancel()
                self.ws = None

    async def start(self) -> None:
        backoff = self.reconnect_base
        while self.running:
            try:
                await self._connect_once()
                backoff = self.reconnect_base
            except ConnectionClosed as e:
                logger.warning("Connection closed: %s", e)
                backoff = self.reconnect_base
            except Exception as e:
                logger.error("Connection error: %s", e)

            if not self.running:
                break
            logger.info("Reconnecting in %ss...", backoff)
            await asyncio.sleep(backoff)
            backoff = min(backoff * 2, self.reconnect_max)

    def stop(self) -> None:
        self.running = False


async def main():
    client = ForexWebSocketClient(api_key="YOUR_API_KEY_HERE")
    await client.start()


if __name__ == "__main__":
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        logger.info("Stopped")

import asyncio
import json
import uuid
import logging
from typing import Optional
import websockets
from websockets.exceptions import ConnectionClosed

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s %(levelname)s %(message)s"
)
logger = logging.getLogger("forex-ws")

PAIRS = "EURUSD,GBPUSD,USDJPY,AUDUSD,USDCAD"

class ForexWebSocketClient:
    """Real-time forex streaming client with auto-reconnect."""

    def __init__(self, api_key: str):
        self.url = f"wss://data.infoway.io/ws?business=common&apikey={api_key}"
        self.ws: Optional[websockets.WebSocketClientProtocol] = None
        self.running = True
        self.reconnect_base = 5
        self.reconnect_max = 60
        self.heartbeat_interval = 30
        self._heartbeat_task: Optional[asyncio.Task] = None

    def _trace(self) -> str:
        return str(uuid.uuid4())

    async def _send(self, msg: dict) -> None:
        if self.ws:
            await self.ws.send(json.dumps(msg))

    async def _subscribe(self) -> None:
        # Subscribe to live trades
        await self._send({
            "code": 10000,
            "trace": self._trace(),
            "data": {"codes": PAIRS}
        })
        await asyncio.sleep(5)

        # Subscribe to order book
        await self._send({
            "code": 10003,
            "trace": self._trace(),
            "data": {"codes": PAIRS}
        })
        await asyncio.sleep(5)

        # Subscribe to 1-minute candles
        await self._send({
            "code": 10006,
            "trace": self._trace(),
            "data": {
                "arr": [{"type": 1, "codes": PAIRS}]
            }
        })
        logger.info("Subscribed to %s", PAIRS)

    def _start_heartbeat(self) -> None:
        if self._heartbeat_task and not self._heartbeat_task.done():
            self._heartbeat_task.cancel()

        async def beat():
            while True:
                await asyncio.sleep(self.heartbeat_interval)
                if not self.ws or self.ws.close_code is not None:
                    break
                try:
                    await self._send({"code": 10010, "trace": self._trace()})
                    logger.debug("Heartbeat sent")
                except Exception:
                    break

        self._heartbeat_task = asyncio.create_task(beat())

    def _handle(self, raw: str) -> None:
        try:
            msg = json.loads(raw)
        except json.JSONDecodeError:
            logger.error("Bad message: %s", raw)
            return

        code = msg.get("code")
        data = msg.get("data", {})

        if code == 10002:       # Trade push
            logger.info("Trade  %s @ %s", data.get("s"), data.get("p"))
        elif code == 10005:     # Depth push
            logger.info("Depth  %s bid=%s ask=%s",
                        data.get("s"),
                        data.get("b", [[None]])[0][0],
                        data.get("a", [[None]])[0][0])
        elif code == 10008:     # Candle push
            logger.info("Candle %s o=%s h=%s l=%s c=%s",
                        data.get("s"), data.get("o"),
                        data.get("h"), data.get("l"), data.get("c"))
        elif code == 10010:
            logger.debug("Heartbeat ack")
        elif code in (10001, 10004, 10007):
            logger.info("Subscription confirmed (code=%s)", code)
        else:
            logger.debug("Message: %s", raw)

    async def _connect_once(self) -> None:
        async with websockets.connect(self.url) as ws:
            self.ws = ws
            logger.info("Connected to %s", self.url)
            await self._subscribe()
            self._start_heartbeat()
            try:
                async for message in ws:
                    self._handle(message)
            finally:
                if self._heartbeat_task:
                    self._heartbeat_task.cancel()
                self.ws = None

    async def start(self) -> None:
        backoff = self.reconnect_base
        while self.running:
            try:
                await self._connect_once()
                backoff = self.reconnect_base
            except ConnectionClosed as e:
                logger.warning("Connection closed: %s", e)
                backoff = self.reconnect_base
            except Exception as e:
                logger.error("Connection error: %s", e)

            if not self.running:
                break
            logger.info("Reconnecting in %ss...", backoff)
            await asyncio.sleep(backoff)
            backoff = min(backoff * 2, self.reconnect_max)

    def stop(self) -> None:
        self.running = False


async def main():
    client = ForexWebSocketClient(api_key="YOUR_API_KEY_HERE")
    await client.start()


if __name__ == "__main__":
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        logger.info("Stopped")

WebSocket Protocol Reference

One connection supports subscribing to up to 600 symbols simultaneously. The server will drop the connection if no heartbeat is received within 60 seconds, so make sure your client sends one every 30 seconds.

Frequently Asked Questions

When is the forex market open?

The forex market trades 24 hours a day, five days a week. It opens Sunday evening (New York time) with the Sydney session, and the major liquidity windows are the London session (roughly 3am–12pm ET) and the New York session (8am–5pm ET). The overlap between London and New York (8am–12pm ET) is typically when spreads are tightest and volume is highest.

How do I query multiple currency pairs at once?

Comma-separate the symbols in the REST endpoint path or in the codes field of your WebSocket subscription message. REST supports up to 100 symbols per request. WebSocket supports up to 600 per connection.

What is the latency on the price feed?

Under normal market conditions, the measured latency between a market event and data availability via WebSocket is under 100ms. REST requests add a round-trip on top of that, so WebSocket is the right choice for latency-sensitive applications.

Does Infoway API provide historical forex data?

Yes. You can pull minute-level historical data going back 3 years by passing a timestamp parameter in the candle request body. Daily and weekly candles have no lookback limit.

What’s the difference between USDCNY and USDCNH?

CNY is the onshore Chinese yuan (traded on the mainland, subject to PBOC controls). CNH is the offshore yuan traded in Hong Kong and other international markets — it moves more freely based on global supply and demand. The two rates often diverge slightly, and that spread itself can be a useful signal.

Is there a free trial?

Yes, register on the Infoway website and you’ll get a 7-day trial automatically. No credit card required. The trial lets you query all markets and data types, with a rate limit of 60 REST requests per minute and up to 10 WebSocket subscriptions. Feel free to reach out to our support team on Telegram if you have any questions during the trial.