RateRadar — the exchange rate app that tells you if today is a good day

Every converter shows you the rate. Almost none tell you whether it is a good one. RateRadar scores today against the recent range and gives you a verdict.

A number without context is not information

You are about to move money — paying an overseas invoice, funding a trip, sending remittance home — and you look up the rate. It says 8.42. Is that good? Without knowing where it has been for the past few months, the number tells you nothing, and “I'll wait and see” turns into converting at whatever the rate happens to be on the day you run out of time.

RateRadar reframes the question. It compares the current rate against its recent range for that pair and returns a plain verdict — is this near the good end, the bad end, or the middle — so the decision to act or wait is based on something.

What the exchange rate app does

A converter is the front door; the judgement is the product.

• A verdict, not just a rate. Each watched pair is scored against its own recent history: the 30-day median and the 90-day high. Hit the 90-day high and you get the strongest exchange now signal; more than 3% above the median reads as a good deal, within 3% is normal, and more than 3% below says wait. The verdict appears as a pill beside the rate, so the answer is legible at a glance rather than buried in a chart.
• A backtest of that verdict. The currency detail screen shows how the same call would have performed historically. A recommendation you cannot check is just an opinion; showing the track record is the difference between a signal and a horoscope.
• The spread you will actually be charged. The detail view separates the interbank rate from what a bank typically gives — roughly two per cent worse — and what a bureau de change gives, around one and a half per cent worse. Knowing that gap is often worth more than timing the market, because it is the part you can control by choosing where to change money.
• Watches and alerts. Put a pair on watch with a target and the app checks in the background and notifies you when it is hit, so you are not opening an app every morning to look at a number.
• A converter that works offline. Rates are cached locally with a freshness indicator showing when they were last updated, and an offline banner when there is no connection. You still get a conversion on a plane or in a country where your data has not connected yet.
• Bilingual. The interface runs in English and Chinese, with the verdict and spread explanations written in both.

Why the verdict is the point

There is no shortage of currency converters, and they are all accurate, because the mid-market rate is a public number. Accuracy is not what is missing. What is missing is judgement: whether the rate in front of you is one worth taking. RateRadar is built around that single question, and it is honest about the answer by publishing the backtest rather than asserting confidence.

It also refuses to hide the spread. Most currency apps quote the interbank rate and let you discover at the counter that you are getting something else. Showing the typical bank and bureau haircut up front is less flattering and considerably more useful.

Who it is for

Anyone with a recurring cross-border payment gets the most from it — a freelancer invoicing in another currency, a parent paying overseas tuition, someone sending money to family. These are not one-off conversions, and over a year the difference between converting on good days and bad days is real money.

It also suits travellers planning a trip a few months out who want to convert before departure rather than at an airport counter, and anyone in Hong Kong watching a pair like HKD to JPY or HKD to GBP where the range moves enough to matter but not enough to follow daily.

Where the rates come from

Rates are fetched from a public exchange-rate feed and cached on the device with a visible last-updated stamp, so you always know how fresh the number is. The spread figures for banks and bureaux are typical indications, not quotes — the counter in front of you sets the real price.

Watches, history and settings are stored locally. There is no account. The verdict is a heuristic based on the recent range, not a forecast, and nothing in the app is financial advice. It is free and ad-supported.

Frequently asked questions

How does the app decide whether today is a good day? It scores the current rate against that pair's own 30-day median and 90-day high. At or above the 90-day high is the strongest exchange-now signal; more than 3% above the median is a good deal, within 3% is normal, more than 3% below says wait. The detail screen backtests how that call would have performed.

Will I get the rate the app shows? No — and the app is explicit about it. It shows the interbank rate alongside the typical haircut from a bank (about 2%) or a bureau de change (about 1.5%), so you know what to expect at the counter.

Can it notify me when a rate hits a target? Yes. Add the pair to your watches with a target; the app checks in the background and sends a local notification when it is hit.

Does the converter work without a connection? Yes. The last fetched rates are cached and used offline, with a freshness stamp showing how old they are.

Which languages does it support? English and Chinese.