How Often Are Exchange Rates Updated? Real-Time vs Daily Explained

"How often are the rates updated?" is the single most asked question about exchange rate APIs. It shows up in every API's FAQ, every developer forum thread, and every Stack Overflow comparison. And for good reason — the answer determines whether an API is suitable for your project or a liability waiting to happen.

This article breaks down what "update frequency" actually means, why it matters more than you think, and how to choose the right API based on your use case.

The Three Layers of "Update Frequency"

When an API says "rates updated every X," that statement hides three separate concerns:

1. Real-Time vs Delayed Data

The forex market trades 24 hours a day, 5 days a week. Currency prices change every second. An API's update frequency tells you how closely it tracks those changes:

• Real-time (seconds to minutes): Pulls from live interbank market feeds. Essential for trading platforms, payment processors, and any app where a 1% swing matters.
• Hourly: A middle ground. Acceptable for dashboards and reporting, but can miss intraday volatility.
• Daily: A single snapshot, usually from the European Central Bank (ECB) at 16:00 CET. Fine for accounting, invoicing, and apps where yesterday's rate is good enough.

2. The "Free Tier" Trap

Most exchange rate APIs advertise real-time capabilities but lock them behind paid plans. Here is what free tiers actually deliver:

Notice the pattern: most free tiers give you daily rates only. You build your app, test it, ship it — and then discover during market volatility that your "exchange rate feature" is showing yesterday's price.

3. Accuracy vs Latency: What Does "Real-Time" Actually Mean?

This is the subtlety most developers miss. "Real-time" can mean two very different things:

• Real-time source: The underlying data comes from live interbank market feeds (Reuters, Bloomberg, Tier 1 banks). The rate itself is current.
• Real-time delivery: The API responds quickly, but the data might be a cached snapshot from hours ago. The delivery is fast, but the data is stale.

Always ask: "Is the data real-time, or just the API response?"

AllRatesToday sources data from Reuters (Refinitiv) and interbank market feeds — the same sources used by Google Finance, XE, and Bloomberg. The rates are genuinely live, not cached ECB snapshots served quickly.

Which Update Frequency Do You Actually Need?

How to Verify an API's Update Frequency

Don't take marketing claims at face value. Here is a simple test you can run:

# Fetch the rate, wait 2 minutes, fetch again
# Compare the timestamps and values

curl -s "https://allratestoday.com/api/v1/rates?source=USD&target=EUR" \
  -H "Authorization: Bearer YOUR_API_KEY" | jq '.time, .rate'

sleep 120

curl -s "https://allratestoday.com/api/v1/rates?source=USD&target=EUR" \
  -H "Authorization: Bearer YOUR_API_KEY" | jq '.time, .rate'

If the timestamps are different and the rate has changed (even slightly), the API is genuinely updating. If both calls return the exact same timestamp, you are getting cached daily data regardless of what the docs claim.

The Bottom Line

• Daily rates are fine for accounting and reporting.
• Hourly rates work for dashboards and non-transactional displays.
• Real-time rates are essential for payments, e-commerce, and anything where money changes hands based on the rate.
• Most free APIs give you daily data. Check the fine print before building on top of it.