ApiService.cs

public async Task<TResponse> GetAsJsonAsync<TResponse>(string uri)
{
    var httpClient = new HttpClient();
    var response = await httpClient.GetAsync(uri);
            
    if (!response.IsSuccessStatusCode)
    {
        throw new Exception();
    }

    return await response.Content.ReadFromJsonAsync<TResponse>();
}

public async Task<TResponse> PostAsJsonAsync<TContent, TResponse>(string uri, TContent content)
{
    var httpClient = new HttpClient();
    var response = await httpClient.PostAsJsonAsync(uri, content);
            
    if (!response.IsSuccessStatusCode)
    {
        throw new Exception();
    }
            
    return await response.Content.ReadFromJsonAsync<TResponse>();
}