How to check if base64 url is an image in c#

You can check if a base64 URL is an image in C# by decoding the base64 string and checking if the result is a valid image format. Here's an example code snippet:

public static bool IsBase64UrlAnImage(string base64Url)
{
    try
    {
        // Remove data URI scheme if present
        if (base64Url.StartsWith("data:image"))
        {
            base64Url = base64Url.Split(',')[1];
        }
        
        // Decode base64 string to byte array
        byte[] imageBytes = Convert.FromBase64String(base64Url);

        // Check if byte array can be converted to image
        using (MemoryStream ms = new MemoryStream(imageBytes))
        {
            Image.FromStream(ms);
        }

        return true;
    }
    catch
    {
        return false;
    }
}

The function first checks if the base64 URL has a data URI scheme (data:image) and removes it if present. Then, it decodes the base64 string to a byte array and tries to create an Image object from it. If the byte array can be converted to an image, the function returns true. Otherwise, it returns false