Hi, I’m assuming you are using Nominatim, the search function on OpenStreetMaps. Nominatim is designed primarily for finding individual locations by name or address, not listing all POIs of a given type in an area. It is just one of many different searches that can use osm data, each has their advantage/disadvantage

It offers a layer=railway filter, which allows matching of railway infrastructure (such as railways), but very few stations are indexed in its database—so results may be incomplete even if you use the correct filters

Best Approach: Use the Overpass API

Overpass Turbo Wizard (beginner option)

Go to overpass-turbo.eu, open the Wizard, and enter: railway=station in Singapore

It will translate into a full Overpass QL query and show all nodes/ways tagged railway=station within Singapore.