UK Postcode Nearest Lookup

Use this endpoint when you need to discover all UK postcodes within a specific geographic radius of known coordinates, especially when distance from the query point matters (e.g. building delivery zones, catchment areas, or proximity-ranked lists). Prefer this over a text search or single postcode lookup when you have lat/lng rather than a postcode or address, and you need multiple nearby results with distances.

• Radius out of range (must be 100–2000m) returns validation error
• Limit out of range (must be 1–100) returns validation error
• Invalid or missing lat/lng returns a bad request error
• No postcodes found within the specified radius returns an empty list
• Coordinates outside the UK may return empty results or unexpected data
• Payment failure or insufficient balance returns 402 error