diff --git a/src/isnd/Controllers/Packages/PackagesController.GetPackage.cs b/src/isnd/Controllers/Packages/PackagesController.GetPackage.cs
index 8e42b69..182184a 100644
--- a/src/isnd/Controllers/Packages/PackagesController.GetPackage.cs
+++ b/src/isnd/Controllers/Packages/PackagesController.GetPackage.cs
@@ -1,5 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using System.IO;
+using System.Linq;
 using Microsoft.AspNetCore.Mvc;
 using Isn.Abstract;
 using isnd.Entities;
@@ -10,13 +11,28 @@ namespace isnd.Controllers
 
     public partial class PackagesController
     {
-        // Web get the paquet
-        [HttpGet("~/" + Constants.APIPrefix + ApiConfig.GetPackage + "/{id}/{lower}/{idf}-{lowerf}."
+        // NuGet v3 flat-container versions index.
+        [HttpGet("~/" + Constants.APIPrefix + ApiConfig.GetPackage + "/{id}/" + ApiConfig.IndexDotJson)]
+        public IActionResult GetPackageVersionsById(
+            [FromRoute][SafeName][Required] string id)
+        {
+            var versions = dbContext.PackageVersions
+                .Where(v => v.PackageId.ToLower() == id.ToLower())
+                .Select(v => v.FullString)
+                .Distinct()
+                .OrderBy(v => v)
+                .ToArray();
+
+            return Ok(new { versions });
+        }
+
+        // NuGet v3 flat-container package download by filename, e.g. id.version.nupkg.
+        [HttpGet("~/" + Constants.APIPrefix + ApiConfig.GetPackage + "/{id}/{lower}/{filename}."
         + Constants.PaquetFileEstension)]
-        public IActionResult GetPackage(
-           [FromRoute][SafeName][Required] string id, 
+        public IActionResult GetPackageByFilename(
+           [FromRoute][SafeName][Required] string id,
            [FromRoute][SafeName][Required] string lower,
-            [FromRoute] string idf, [FromRoute] string lowerf)
+           [FromRoute][SafeName][Required] string filename)
         {
             var pkgpath = Path.Combine(isndSettings.PackagesRootDir,
             id, lower, $"{id}-{lower}." + Constants.PaquetFileEstension
@@ -32,6 +48,8 @@ namespace isnd.Controllers
         }
 
         // Web get spec
+        [HttpGet("~/" + Constants.APIPrefix + Constants.SpecFileEstension + "/{id}/{lower}/{idf}.{lowerf}."
+        + Constants.SpecFileEstension)]
         [HttpGet("~/" + Constants.APIPrefix + Constants.SpecFileEstension + "/{id}/{lower}/{idf}-{lowerf}."
         + Constants.SpecFileEstension)]
         public IActionResult GetNuspec(
diff --git a/src/isnd/Services/PackageManager.cs b/src/isnd/Services/PackageManager.cs
index 84ac2c0..0ba1c04 100644
--- a/src/isnd/Services/PackageManager.cs
+++ b/src/isnd/Services/PackageManager.cs
@@ -50,7 +50,8 @@ namespace isnd.Services
                 },
                 // under dev, only leash in release mode
 
-                new Resource(extUrl + ApiConfig.GetPackage, "PackageBaseAddress/3.0.0")
+                // NuGet clients expect a trailing slash on PackageBaseAddress to resolve relative paths.
+                new Resource(extUrl + ApiConfig.GetPackage + "/", "PackageBaseAddress/3.0.0")
                 {
                     Comment = @"Package Base Address service - Base URL of where NuGet packages are stored, in the format https://<host>/nupkg/{id-lower}/{version-lower}/{id-lower}.{version-lower}.nupkg"
                 },
diff --git a/test/isnd.tests/UnitTestWebHost.cs b/test/isnd.tests/UnitTestWebHost.cs
index e7386e8..126372a 100644
--- a/test/isnd.tests/UnitTestWebHost.cs
+++ b/test/isnd.tests/UnitTestWebHost.cs
@@ -17,9 +17,11 @@ using Microsoft.AspNetCore.DataProtection;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
+using NuGet.Common;
 using NuGet.Configuration;
 using NuGet.Protocol;
 using NuGet.Protocol.Core.Types;
+using NuGet.Versioning;
 using Xunit;
 
 namespace isnd.host.tests
@@ -168,6 +170,63 @@ namespace isnd.host.tests
             await AssertAutocompleteContainsPushedVersionAsync(DummyPackageId, DummyPackageVersion);
         }
 
+        [Fact]
+        public async Task NuGetV3ProtocolCanDownloadDummyPackage()
+        {
+            var apiKeyValue = $"dummy-key-{Guid.NewGuid():N}";
+            var packagePath = GetDummyArtifactPath();
+            Assert.True(File.Exists(packagePath), $"Missing dummy artifact at {packagePath}");
+
+            using (var serviceScope = server.Host.Services.CreateScope())
+            {
+                var dbContext = serviceScope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
+                var userId = $"dummy-user-{Guid.NewGuid():N}";
+
+                await ResetDummyPackageStateAsync(serviceScope.ServiceProvider, dbContext);
+
+                dbContext.Users.Add(new ApplicationUser
+                {
+                    Id = userId,
+                    UserName = userId,
+                    NormalizedUserName = userId.ToUpperInvariant(),
+                    Email = $"{userId}@tests.local",
+                    NormalizedEmail = $"{userId}@tests.local".ToUpperInvariant(),
+                    EmailConfirmed = true
+                });
+
+                dbContext.ApiKeys.Add(new ApiKey
+                {
+                    Id = apiKeyValue,
+                    UserId = userId,
+                    Name = "dummy-key",
+                    CreationDate = DateTime.UtcNow,
+                    ValidityPeriodInDays = 30
+                });
+
+                await dbContext.SaveChangesAsync();
+            }
+
+            await PushPackageAsync(packagePath, apiKeyValue);
+
+            var indexUrl = GetServerBaseUrl() + "/" + Constants.APIPrefix + "index.json";
+            var repository = Repository.Factory.GetCoreV3(indexUrl);
+            var findPackageById = await repository.GetResourceAsync<FindPackageByIdResource>();
+            Assert.NotNull(findPackageById);
+
+            await using var nupkgStream = new MemoryStream();
+            using var cache = new SourceCacheContext();
+            var copied = await findPackageById.CopyNupkgToStreamAsync(
+                DummyPackageId,
+                NuGetVersion.Parse(DummyPackageVersion),
+                nupkgStream,
+                cache,
+                NullLogger.Instance,
+                CancellationToken.None);
+
+            Assert.True(copied, "NuGet v3 client could not download the package from the feed.");
+            Assert.True(nupkgStream.Length > 0, "Downloaded package stream is empty.");
+        }
+
         [Fact]
         public void TestRegistrationV3Resource()
         {