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.NET integration guide

Call the LatLongAPI from .NET with a JSON POST request, server-side license configuration, and HTTP error handling.

Configure your application

Use the .NET 10 SDK. Create a console application, then replace Program.cs with the example below. The example uses built-in HttpClient and JSON support, with no additional packages.

dotnet new console --name LatLongExample --framework net10.0
cd LatLongExample

In a Bash or compatible shell, set LATLONG_API_BASE_URL to your assigned HTTPS origin and LATLONG_API_LICENSE to your license. For testing, use the test origin below with a test license. Replace YOUR_TEST_LICENSE with the license issued for that environment. Keep the license outside source control and browser code.

export LATLONG_API_BASE_URL="https://v1-dev.latlongapi.com"
export LATLONG_API_LICENSE="YOUR_TEST_LICENSE"

Request an address

using System.Net.Http.Json;
using System.Text.Json.Serialization;

internal static class Program
{
    private static async Task Main()
    {
        string baseUrl = Environment.GetEnvironmentVariable("LATLONG_API_BASE_URL")
            ?? throw new InvalidOperationException("Set LATLONG_API_BASE_URL");
        string license = Environment.GetEnvironmentVariable("LATLONG_API_LICENSE")
            ?? throw new InvalidOperationException("Set LATLONG_API_LICENSE");

        using var client = new HttpClient
        {
            BaseAddress = new Uri(baseUrl.TrimEnd('/') + "/"),
            Timeout = TimeSpan.FromSeconds(10)
        };

        var request = new ReverseRequest(51.5007, -0.1246, license);
        using var response = await client.PostAsJsonAsync("api/v1/reverse", request);
        response.EnsureSuccessStatusCode();

        var data = await response.Content.ReadFromJsonAsync<ReverseResponse>()
            ?? throw new InvalidOperationException("The response body was empty");
        Console.WriteLine(data.Result.ShortAddress);
    }
}

internal sealed record ReverseRequest(
    [property: JsonPropertyName("lat")] double Latitude,
    [property: JsonPropertyName("long")] double Longitude,
    [property: JsonPropertyName("api")] string License);

internal sealed record ReverseResult(
    [property: JsonPropertyName("short_address")] string ShortAddress);

internal sealed record ReverseResponse(
    [property: JsonPropertyName("result")] ReverseResult Result);

Run the example

dotnet run

Use the result

The example prints result.short_address. Read result.long_address for a longer description. Check nullable city and country fields before displaying them.

Handle failures in your service

Set a timeout, catch request errors, and record the status and request identifier without logging the license. Retry temporary failures with bounded backoff. A 401 requires a valid license; a 422 requires correcting the input.

LatLongAPI reference and request limits · Compare plans