During a heavy downpour in Hanoi, Tuan Minh, who works in Cau Giay District, checked VRain instead of his iPhone’s default weather app to see real-time rainfall data near his home.

"68 mm. Heavy rain," the app displayed, with the numbers shifting from blue to orange to signal intensity, enough for him to expect flooding on the road near his house.

For more than a year, VRain has been his go-to app, especially during severe weather or business trips to other provinces.

"Other apps just say whether it will rain or not. This one shows exactly how much rain has fallen. Sometimes just a few kilometers apart, rainfall can be completely different," he says.

Developed by Vietnamese company Watec, VRain appeals to users looking for real-time observational data over general forecasts.

In early May, Apple highlighted it on the App Store as an example of a Vietnamese-developed platform benefiting tens of thousands of users.

Founded in 2003 in Da Nang, Watec initially focused on environmental monitoring systems serving meteorological agencies and disaster management authorities.

The VRain interface on a mobile phone. Photo by Luu Quy

From an internal system to a public weather app

According to CEO Van Phu Chinh, a decade ago the company mainly provided technical consulting and worked closely with local governments. But during the implementation of governmental projects, the team found that many important decisions lacked real-time data for reference.

By 2015, as extreme weather events such as localized heavy rainfall, flooding, and saltwater intrusion up rivers became more frequent, the team identified a major gap: environmental monitoring data in Vietnam was limited, fragmented, and slow to update.

Instead of remaining a consultancy, Watec built its own monitoring network, investing in IoT devices, data transmission systems, cloud infrastructure, and analytical software. To monitor the highly localized precipitation, it set up thousands of monitoring stations nationwide.

"When the network reached sufficient scale, we realized the data shouldn’t remain on internal dashboards. Ordinary people are the ones who need real-time data the most," Chinh says.

VRain was then launched as a free public app. Rather than offering only forecasts, it displays detailed rainfall measurements in millimeters from specific local stations, enabling users to keep tabs on rainfall, water levels, and potential flooding in their area.

Mr. Van Phu Chinh. Photo courtesy of the subject

Developers faced the challenge of translating complex technical data into an accessible format. Even a simple rainfall display requires multiple backend layers, from monitoring equipment and data transmission to server processing and user interface design.

The app was built with a clean, ad-free interface, prioritizing speed and reliability, especially during extreme weather events.

In addition to iOS and Android apps, VRain offers a web version with integrated maps and supplementary data from Windy to provide broader information.

Some users note that VRain focuses more on raw data than visual design compared to international apps like Apple Weather or AccuWeather.

Minh describes its interface as simple and fast-loading, even in weak network conditions, but somewhat less visually engaging.

Moreover, monitoring stations are currently concentrated in certain regions such as the northwest, southwest, and some central provinces, meaning coverage is not comprehensive nationally.

Traffic surges during periods of heavy rain, storms, or flooding, requiring the system to process a spike in alerts while thousands of stations continue operating reliably, Chinh says.

"Seeing data flow continuously from thousands of stations during extreme weather—and knowing it helps someone make safer decisions—is very meaningful.

"We see ourselves not just as an equipment supplier or consultancy, but as a technology company working in the environmental and natural disaster sector."

The VRain web interface integrates data from Windy and displays more than 2,700 rainfall monitoring stations nationwide. Screenshot photo

Looking ahead, VRain plans major upgrades. Beyond rainfall data, the platform will expand to include wind levels, flood risk, air quality, and disaster alerts, leveraging Watec’s nationwide monitoring network.

A future version will also integrate AI, allowing users to ask questions in Vietnamese. The long-term goal is to build a real-time environmental data assistant for the public.

"We believe environmental data should no longer be limited to specialized agencies, but become essential infrastructure for society as a whole," Chinh adds.