Integrating Google Maps & Web Services in ASP.NET Core Web API

Author: Dasan | Date: April 11, 2025

1. 🎯 Introduction

In this post, we’ll cover how to use Google Maps and a suite of supporting APIs in an ASP.NET Core Web API backend. We'll include:

• Places API
• Directions API (Legacy)
• Distance Matrix API (Legacy)
• Elevation API
• Geocoding API
• Roads API

2. 🔑 Get Your Google Maps API Key

1. Visit Google Cloud Console.
2. Create a new project and enable the APIs listed above.
3. Generate your API key from the "Credentials" section.
4. Apply restrictions (IP or domain-based) for security.

3. 🧰 Setup Your ASP.NET Core Web API

Make sure HttpClient is configured:

// Program.cs
builder.Services.AddHttpClient();

4. 🧪 API Integrations

4.1 📍 Places API

// GET /api/google/places?query=restaurants in Chennai
[HttpGet("places")]
public async Task<IActionResult> GetPlaces([FromQuery] string query)
{
    var url = $"https://maps.googleapis.com/maps/api/place/textsearch/json?query={Uri.EscapeDataString(query)}&key={_apiKey}";
    var response = await _httpClient.GetStringAsync(url);
    return Content(response, "application/json");
}

4.2 🛣️ Directions API (Legacy)

Note: Transit directions are excluded.

// GET /api/google/directions?origin=Chennai&destination=Bangalore
[HttpGet("directions")]
public async Task<IActionResult> GetDirections(string origin, string destination)
{
    var url = $"https://maps.googleapis.com/maps/api/directions/json?origin={origin}&destination={destination}&mode=driving&key={_apiKey}";
    var response = await _httpClient.GetStringAsync(url);
    return Content(response, "application/json");
}

4.3 🚗 Distance Matrix API (Legacy)

// GET /api/google/distance?origins=Chennai&destinations=Bangalore
[HttpGet("distance")]
public async Task<IActionResult> GetDistanceMatrix(string origins, string destinations)
{
    var url = $"https://maps.googleapis.com/maps/api/distancematrix/json?origins={origins}&destinations={destinations}&mode=driving&key={_apiKey}";
    var response = await _httpClient.GetStringAsync(url);
    return Content(response, "application/json");
}

4.4 ⛰️ Elevation API

// GET /api/google/elevation?locations=27.9881,86.9250
[HttpGet("elevation")]
public async Task<IActionResult> GetElevation(string locations)
{
    var url = $"https://maps.googleapis.com/maps/api/elevation/json?locations={locations}&key={_apiKey}";
    var response = await _httpClient.GetStringAsync(url);
    return Content(response, "application/json");
}

4.5 🧭 Geocoding API

// GET /api/google/geocode?address=New York
[HttpGet("geocode")]
public async Task<IActionResult> Geocode(string address)
{
    var url = $"https://maps.googleapis.com/maps/api/geocode/json?address={Uri.EscapeDataString(address)}&key={_apiKey}";
    var response = await _httpClient.GetStringAsync(url);
    return Content(response, "application/json");
}

4.6 🛤️ Roads API (Snap to Roads)

// GET /api/google/roads?path=60.170880,24.942795|60.170879,24.942796
[HttpGet("roads")]
public async Task<IActionResult> SnapToRoads(string path)
{
    var url = $"https://roads.googleapis.com/v1/snapToRoads?path={path}&key={_apiKey}";
    var response = await _httpClient.GetStringAsync(url);
    return Content(response, "application/json");
}

5. 🔐 Secure Your API Key

• Store your key in appsettings.json or environment variables.
• Limit API usage to specific referrers or IPs in Google Console.

6. 🏁 Conclusion

You’ve successfully integrated a full suite of Google Maps Web APIs into your ASP.NET Core Web API. These endpoints now serve as your backend support for frontend apps using Maps, Places, Geocoding, and more.

In the next blog, we’ll explore how to connect these APIs with a React Native frontend for a real-time mobile experience.