diff --git a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Pages/SenderPage.razor b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Pages/SenderPage.razor
index 2b5a2184..04f5d0e7 100644
--- a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Pages/SenderPage.razor
+++ b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Pages/SenderPage.razor
@@ -19,6 +19,7 @@
 @inject EnvelopeGenerator.Server.Client.Services.ThemeService ThemeService
 @inject EnvelopeGenerator.Server.Client.Services.UserPreferencesService UserPreferencesService
 @inject EnvelopeGenerator.Server.Client.Services.CustomImagesService CustomImagesService
+@inject EnvelopeGenerator.Server.Client.Services.PdfSignatureService PdfSignatureService
 @inject EnvelopeGenerator.Server.Client.Services.CreateEnvelopeBootstrapStorageService CreateEnvelopeBootstrapStorageService
 @inject ILogger<SenderPage> Logger
 @inject NavigationManager Navigation
@@ -424,7 +425,7 @@
 
 @* ── PDF Vorschau Popup ────────────────────────────────────────────────── *@
 <DxPopup @bind-Visible="@_previewVisible"
-         HeaderText="@($"{L("Preview", "Vorschau")} — {_selectedEnvelope?.Title} (#{_selectedEnvelope?.Id})")"
+         HeaderText="@($"{(_activeTab == "completed" && _selectedEnvelope?.Status == EnvelopeStatus.EnvelopeCompletelySigned ? L("SignedPdf", "Signiertes PDF") : L("Preview", "Vorschau"))} — {_selectedEnvelope?.Title} (#{_selectedEnvelope?.Id})")"
          Width="80vw"
          MaxWidth="80vw"
          Height="90vh"
@@ -1024,12 +1025,14 @@
 
     private async Task OpenPreviewAsync(EnvelopeDto envelope)
     {
+        var showSigned = _activeTab == "completed" && envelope.Status == EnvelopeStatus.EnvelopeCompletelySigned;
+
         // Unmount the viewer first — let the previous instance fully dispose
         _previewViewerMounted = false;
         _previewPdfBytes = null;
         _previewPageCount = 0;
         _previewPagePreviews = [];
-        _previewFileName = $"envelope-{envelope.Id}.pdf";
+        _previewFileName = showSigned ? $"envelope-{envelope.Id}-signed.pdf" : $"envelope-{envelope.Id}.pdf";
         _previewErrorMessage = null;
         _previewLoading = true;
         _previewVisible = true;
@@ -1037,7 +1040,10 @@
 
         try
         {
-            _previewPdfBytes = await DocumentService.GetSenderDocumentBytesByEnvelopeIdAsync(envelope.Id);
+            _previewPdfBytes = showSigned
+                ? await PdfSignatureService.GetSignedPdfAsync(envelope.Id)
+                : await DocumentService.GetSenderDocumentBytesByEnvelopeIdAsync(envelope.Id);
+
             if (_previewPdfBytes is null || _previewPdfBytes.Length == 0)
             {
                 _previewErrorMessage = L("DocumentCouldNotBeLoaded", "Dokument konnte nicht geladen werden");
diff --git a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Program.cs b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Program.cs
index b221ad7e..c70a4814 100644
--- a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Program.cs
+++ b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Program.cs
@@ -53,6 +53,7 @@ builder.Services.AddScoped<ThemeService>();
 
 // Logo configuration (loaded once after login, in-memory cached)
 builder.Services.AddScoped<CustomImagesService>();
+builder.Services.AddScoped<PdfSignatureService>();
 
 // DevExpress WASM
 builder.Services.AddDevExpressWebAssemblyBlazorPdfViewer();
diff --git a/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/PdfSignatureService.cs b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/PdfSignatureService.cs
new file mode 100644
index 00000000..99a1f868
--- /dev/null
+++ b/EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Services/PdfSignatureService.cs
@@ -0,0 +1,24 @@
+using System.Net;
+using System.Net.Http.Json;
+
+namespace EnvelopeGenerator.Server.Client.Services;
+
+public class PdfSignatureService(IHttpClientFactory httpClientFactory)
+{
+    /// <summary>
+    /// Calls POST /api/PdfSignature with the envelope id and returns the fully signed PDF bytes.
+    /// </summary>
+    public async Task<byte[]> GetSignedPdfAsync(int envelopeId, CancellationToken cancel = default)
+    {
+        using var http = httpClientFactory.CreateClient("EnvelopeGenerator.Server");
+        var response = await http.PostAsJsonAsync("/api/PdfSignature", new { Id = envelopeId }, cancel);
+
+        if (!response.IsSuccessStatusCode)
+            throw new HttpRequestException(
+                $"Failed to load signed PDF. Status: {(int)response.StatusCode} ({response.ReasonPhrase ?? "Unknown"})",
+                null,
+                response.StatusCode);
+
+        return await response.Content.ReadAsByteArrayAsync(cancel);
+    }
+}
diff --git a/EnvelopeGenerator.Server/EnvelopeGenerator.Server/Program.cs b/EnvelopeGenerator.Server/EnvelopeGenerator.Server/Program.cs
index cbacf25f..66212b58 100644
--- a/EnvelopeGenerator.Server/EnvelopeGenerator.Server/Program.cs
+++ b/EnvelopeGenerator.Server/EnvelopeGenerator.Server/Program.cs
@@ -344,6 +344,7 @@ try
     builder.Services.AddScoped<EnvelopeGenerator.Server.Client.Services.UserPreferencesService>();
     builder.Services.AddScoped<EnvelopeGenerator.Server.Client.Services.ThemeService>();
     builder.Services.AddScoped<EnvelopeGenerator.Server.Client.Services.CustomImagesService>();
+    builder.Services.AddScoped<EnvelopeGenerator.Server.Client.Services.PdfSignatureService>();
     builder.Services.AddScoped<EnvelopeGenerator.Server.Client.Services.LocalizationService>();
     builder.Services.AddScoped<EnvelopeGenerator.Server.Client.Services.ReceiverService>();
     builder.Services.AddScoped<EnvelopeGenerator.Server.Client.Services.PdfRenderService>();