diff --git a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/AuthService.cs b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/AuthService.cs
index 12db705b..c5e74eef 100644
--- a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/AuthService.cs
+++ b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/AuthService.cs
@@ -1,5 +1,4 @@
 using System.Net;
-using System.Net.Http;
 using System.Net.Http.Json;
 
 namespace EnvelopeGenerator.Server.Client.Services;
@@ -10,6 +9,7 @@ public enum SenderLoginResult { Success, InvalidCredentials, Error }
 
 public class AuthService(IHttpClientFactory httpClientFactory)
 {
+    private HttpClient CreateDefaultClient() => httpClientFactory.CreateClient("EnvelopeGenerator.Server");
 
     /// <summary>
     /// Checks whether the current user holds a valid receiver token for the given envelope key.
@@ -17,7 +17,7 @@ public class AuthService(IHttpClientFactory httpClientFactory)
     /// </summary>
     public async Task<bool> CheckEnvelopeAccessAsync(string envelopeKey, CancellationToken cancel = default)
     {
-        using var http = httpClientFactory.CreateClient("EnvelopeGenerator.Server");
+        using var http = CreateDefaultClient();
         var response = await http.GetAsync($"/api/auth/check/envelope/{Uri.EscapeDataString(envelopeKey)}", cancel);
         return response.StatusCode == HttpStatusCode.OK;
     }
@@ -29,9 +29,11 @@ public class AuthService(IHttpClientFactory httpClientFactory)
     /// </summary>
     public async Task<EnvelopeLoginResult> LoginEnvelopeReceiverAsync(string envelopeKey, string accessCode, CancellationToken cancel = default)
     {
-        using var http = httpClientFactory.CreateClient("EnvelopeGenerator.Server");
-        var form = new MultipartFormDataContent();
-        form.Add(new StringContent(accessCode), "AccessCode");
+        using var http = CreateDefaultClient();
+        var form = new MultipartFormDataContent
+        {
+            { new StringContent(accessCode), "AccessCode" }
+        };
 
         var response = await http.PostAsync(
             $"/api/Auth/envelope-receiver/{Uri.EscapeDataString(envelopeKey)}",
@@ -52,7 +54,7 @@ public class AuthService(IHttpClientFactory httpClientFactory)
     /// </summary>
     public async Task<bool> LogoutEnvelopeReceiverAsync(string envelopeKey, CancellationToken cancel = default)
     {
-        using var http = httpClientFactory.CreateClient("EnvelopeGenerator.Server");
+        using var http = CreateDefaultClient();
         var response = await http.PostAsync(
             $"/api/auth/logout/envelope/{Uri.EscapeDataString(envelopeKey)}",
             null, cancel);
@@ -66,7 +68,7 @@ public class AuthService(IHttpClientFactory httpClientFactory)
     /// </summary>
     public async Task<SenderLoginResult> LoginSenderAsync(string username, string password, CancellationToken cancel = default)
     {
-        using var http = httpClientFactory.CreateClient("EnvelopeGenerator.Server");
+        using var http = CreateDefaultClient();
         var requestBody = new { username, password };
 
         var response = await http.PostAsJsonAsync(
diff --git a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/CultureService.cs b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/CultureService.cs
new file mode 100644
index 00000000..a7b6a7b6
--- /dev/null
+++ b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/CultureService.cs
@@ -0,0 +1,74 @@
+using System.Globalization;
+using Microsoft.JSInterop;
+
+namespace EnvelopeGenerator.Server.Client.Services;
+
+/// <summary>
+/// Service for managing application culture/localization.
+/// </summary>
+public class CultureService
+{
+    private readonly IJSRuntime _jsRuntime;
+    private const string CULTURE_KEY = "AppCulture";
+
+    public CultureService(IJSRuntime jsRuntime)
+    {
+        _jsRuntime = jsRuntime;
+    }
+
+    /// <summary>
+    /// Gets the list of supported cultures.
+    /// </summary>
+    public static CultureInfo[] SupportedCultures { get; } = new[]
+    {
+        new CultureInfo("de-DE"),
+        new CultureInfo("en-US"),
+        new CultureInfo("fr-FR")
+    };
+
+    /// <summary>
+    /// Sets the application culture and stores it in localStorage.
+    /// </summary>
+    public async Task SetCultureAsync(string culture)
+    {
+        if (!SupportedCultures.Any(c => c.Name == culture))
+            throw new ArgumentException($"Culture '{culture}' is not supported.", nameof(culture));
+
+        await _jsRuntime.InvokeVoidAsync("localStorage.setItem", CULTURE_KEY, culture);
+    }
+
+    /// <summary>
+    /// Gets the stored culture from localStorage.
+    /// </summary>
+    public async Task<string?> GetCultureAsync()
+    {
+        try
+        {
+            return await _jsRuntime.InvokeAsync<string?>("localStorage.getItem", CULTURE_KEY);
+        }
+        catch
+        {
+            return null;
+        }
+    }
+
+    /// <summary>
+    /// Initializes the culture from localStorage or browser settings.
+    /// </summary>
+    public async Task<CultureInfo> InitializeCultureAsync()
+    {
+        var storedCulture = await GetCultureAsync();
+        
+        if (!string.IsNullOrEmpty(storedCulture) && 
+            SupportedCultures.Any(c => c.Name == storedCulture))
+        {
+            return new CultureInfo(storedCulture);
+        }
+
+        // Fallback to browser culture or default
+        var browserCulture = CultureInfo.CurrentCulture.Name;
+        var matchedCulture = SupportedCultures.FirstOrDefault(c => c.Name == browserCulture);
+        
+        return matchedCulture ?? SupportedCultures[0]; // Default to German
+    }
+}
diff --git a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/DocReceiverElementService.cs b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/DocReceiverElementService.cs
new file mode 100644
index 00000000..b64e242e
--- /dev/null
+++ b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/DocReceiverElementService.cs
@@ -0,0 +1,24 @@
+using System.Net.Http.Json;
+using System.Text.Json;
+using EnvelopeGenerator.Server.Client.Models;
+using EnvelopeGenerator.Server.Client.Options;
+using Microsoft.Extensions.Options;
+
+namespace EnvelopeGenerator.Server.Client.Services;
+
+public class DocReceiverElementService(HttpClient http, IOptions<ApiOptions> apiOptions)
+{
+    private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
+
+    public async Task<IReadOnlyList<SignatureDto>> GetAsync(string envelopeKey, CancellationToken cancel = default)
+    {
+        var url = $"{apiOptions.Value.BaseUrl}/api/DocReceiverElement/{Uri.EscapeDataString(envelopeKey)}";
+        var response = await http.GetAsync(url, cancel);
+
+        if (!response.IsSuccessStatusCode)
+            throw new HttpRequestException($"Failed to retrieve signatures for envelope {envelopeKey}: {response.StatusCode} {response.ReasonPhrase}");
+
+        var result = await response.Content.ReadFromJsonAsync<List<SignatureDto>>(_jsonOptions, cancel);
+        return result ?? [];
+    }
+}
diff --git a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/EnvelopeService.cs b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/EnvelopeService.cs
new file mode 100644
index 00000000..1acfa669
--- /dev/null
+++ b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/EnvelopeService.cs
@@ -0,0 +1,72 @@
+using System.Net.Http.Json;
+using System.Text.Json;
+using EnvelopeGenerator.Server.Client.Models;
+using EnvelopeGenerator.Server.Client.Options;
+using Microsoft.AspNetCore.WebUtilities;
+using Microsoft.Extensions.Options;
+
+namespace EnvelopeGenerator.Server.Client.Services;
+
+/// <summary>
+/// Retrieves <see cref="EnvelopeDto"/>s from the API.
+/// </summary>
+public class EnvelopeService
+{
+    private readonly HttpClient _http;
+    private readonly ApiOptions _apiOptions;
+    private static readonly JsonSerializerOptions _jsonOptions = new(JsonSerializerDefaults.Web);
+
+    public EnvelopeService(HttpClient http, IOptions<ApiOptions> apiOptions)
+    {
+        _http = http;
+        _apiOptions = apiOptions.Value;
+    }
+
+    /// <summary>
+    /// Fetches envelopes from the API with optional filters.
+    /// </summary>
+    /// <exception cref="HttpRequestException">Thrown when the API request fails.</exception>
+    public async Task<IEnumerable<EnvelopeDto>?> GetAsync(
+        int? id = null,
+        string? uuid = null,
+        bool? onlyActive = null,
+        bool? onlyCompleted = null,
+        CancellationToken cancel = default)
+    {
+        var baseUrl = $"{_apiOptions.BaseUrl}/api/Envelope";
+        var queryParams = new Dictionary<string, string?>();
+
+        if (id.HasValue)
+        {
+            queryParams["Id"] = id.Value.ToString();
+        }
+        if (!string.IsNullOrEmpty(uuid))
+        {
+            queryParams["Uuid"] = uuid;
+        }
+        if (onlyActive.HasValue)
+        {
+            queryParams["OnlyActive"] = onlyActive.Value.ToString();
+        }
+        if (onlyCompleted.HasValue)
+        {
+            queryParams["OnlyCompleted"] = onlyCompleted.Value.ToString();
+        }
+
+        var url = QueryHelpers.AddQueryString(baseUrl, queryParams);
+
+        var response = await _http.GetAsync(url, cancel);
+
+        if (!response.IsSuccessStatusCode)
+        {
+            var statusCode = (int)response.StatusCode;
+            var reasonPhrase = response.ReasonPhrase ?? "Unknown error";
+            throw new HttpRequestException(
+                $"Failed to load envelopes. Status: {statusCode} ({reasonPhrase})",
+                null,
+                response.StatusCode);
+        }
+
+        return await response.Content.ReadFromJsonAsync<IEnumerable<EnvelopeDto>>(_jsonOptions, cancel);
+    }
+}