diff --git a/NEW/tests/JdeScoping.Client.Tests/Services/ApiClientBaseTests.cs b/NEW/tests/JdeScoping.Client.Tests/Services/ApiClientBaseTests.cs
index efc5f98..ecdbacc 100644
--- a/NEW/tests/JdeScoping.Client.Tests/Services/ApiClientBaseTests.cs
+++ b/NEW/tests/JdeScoping.Client.Tests/Services/ApiClientBaseTests.cs
@@ -219,4 +219,169 @@ public class ApiClientBaseTests
         result.IsError.ShouldBeTrue();
         result.Error.StatusCode.ShouldBe(400);
     }
+
+    // POST tests
+
+    [Fact]
+    public async Task PostAsync_Returns200_MapsToSuccessValue()
+    {
+        // Arrange
+        var expected = new TestDto(99, "Created");
+        _mockHttp.When(HttpMethod.Post, "/api/test")
+            .Respond("application/json", JsonSerializer.Serialize(expected));
+
+        // Act
+        var result = await _client.PostAsync<TestDto, TestDto>("/api/test", new TestDto(0, "Input"));
+
+        // Assert
+        result.IsSuccess.ShouldBeTrue();
+        result.Value.Id.ShouldBe(99);
+    }
+
+    [Fact]
+    public async Task PostAsync_Returns401_MapsToUnauthorized()
+    {
+        // Arrange
+        _mockHttp.When(HttpMethod.Post, "/api/test")
+            .Respond(HttpStatusCode.Unauthorized);
+
+        // Act
+        var result = await _client.PostAsync<TestDto, TestDto>("/api/test", new TestDto(0, "Input"));
+
+        // Assert
+        result.IsUnauthorized.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task PostAsync_WithNoBody_Returns200()
+    {
+        // Arrange
+        _mockHttp.When(HttpMethod.Post, "/api/test")
+            .Respond("application/json", JsonSerializer.Serialize(new Unit()));
+
+        // Act
+        var result = await _client.PostAsync<Unit>("/api/test");
+
+        // Assert
+        result.IsSuccess.ShouldBeTrue();
+    }
+
+    // Bytes tests
+
+    [Fact]
+    public async Task GetBytesAsync_Returns200_MapsToSuccessBytes()
+    {
+        // Arrange
+        var expectedBytes = new byte[] { 0x50, 0x4B, 0x03, 0x04 }; // ZIP header
+        _mockHttp.When("/api/download")
+            .Respond("application/octet-stream", new MemoryStream(expectedBytes));
+
+        // Act
+        var result = await _client.GetBytesAsync("/api/download");
+
+        // Assert
+        result.IsSuccess.ShouldBeTrue();
+        result.Value.ShouldBe(expectedBytes);
+    }
+
+    [Fact]
+    public async Task GetBytesAsync_Returns404_MapsToNotFound()
+    {
+        // Arrange
+        _mockHttp.When("/api/download")
+            .Respond(HttpStatusCode.NotFound);
+
+        // Act
+        var result = await _client.GetBytesAsync("/api/download");
+
+        // Assert
+        result.IsNotFound.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task PostForBytesAsync_Returns200_MapsToSuccessBytes()
+    {
+        // Arrange
+        var expectedBytes = new byte[] { 0x50, 0x4B, 0x03, 0x04 };
+        _mockHttp.When(HttpMethod.Post, "/api/download")
+            .Respond("application/octet-stream", new MemoryStream(expectedBytes));
+
+        // Act
+        var result = await _client.PostForBytesAsync("/api/download", new { filter = "test" });
+
+        // Assert
+        result.IsSuccess.ShouldBeTrue();
+        result.Value.ShouldBe(expectedBytes);
+    }
+
+    // Non-GET status code tests
+
+    [Fact]
+    public async Task PostAsync_Returns400_WithValidationErrors_MapsToValidationError()
+    {
+        // Arrange
+        var validationProblem = new Microsoft.AspNetCore.Mvc.ValidationProblemDetails
+        {
+            Errors = { ["Field"] = new[] { "Required" } }
+        };
+        _mockHttp.When(HttpMethod.Post, "/api/test")
+            .Respond(HttpStatusCode.BadRequest, "application/json",
+                JsonSerializer.Serialize(validationProblem, new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase }));
+
+        // Act
+        var result = await _client.PostAsync<TestDto, TestDto>("/api/test", new TestDto(0, "Input"));
+
+        // Assert
+        result.IsValidationError.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task GetBytesAsync_Returns500_MapsToApiError()
+    {
+        // Arrange
+        _mockHttp.When("/api/download")
+            .Respond(HttpStatusCode.InternalServerError, "text/plain", "Server error");
+
+        // Act
+        var result = await _client.GetBytesAsync("/api/download");
+
+        // Assert
+        result.IsError.ShouldBeTrue();
+        result.Error.StatusCode.ShouldBe(500);
+    }
+
+    [Fact]
+    public async Task PostMultipartAsync_Returns401_MapsToUnauthorized()
+    {
+        // Arrange
+        _mockHttp.When(HttpMethod.Post, "/api/upload")
+            .Respond(HttpStatusCode.Unauthorized);
+
+        using var stream = new MemoryStream(new byte[] { 1, 2, 3 });
+
+        // Act
+        var result = await _client.PostMultipartAsync<TestDto>("/api/upload", stream, "test.xlsx");
+
+        // Assert
+        result.IsUnauthorized.ShouldBeTrue();
+    }
+
+    [Fact]
+    public async Task PostMultipartAsync_Returns200_MapsToSuccessValue()
+    {
+        // Arrange
+        var expected = new TestDto(1, "Uploaded");
+        _mockHttp.When(HttpMethod.Post, "/api/upload")
+            .With(req => req.Content?.Headers.ContentType?.MediaType == "multipart/form-data")
+            .Respond("application/json", JsonSerializer.Serialize(expected));
+
+        using var stream = new MemoryStream(new byte[] { 1, 2, 3 });
+
+        // Act
+        var result = await _client.PostMultipartAsync<TestDto>("/api/upload", stream, "test.xlsx");
+
+        // Assert
+        result.IsSuccess.ShouldBeTrue();
+        result.Value.Id.ShouldBe(1);
+    }
 }