diff --git a/src/GeoCop.Api/ContextExtensions.cs b/src/GeoCop.Api/ContextExtensions.cs
index ad890b76..c06b3ea7 100644
--- a/src/GeoCop.Api/ContextExtensions.cs
+++ b/src/GeoCop.Api/ContextExtensions.cs
@@ -75,7 +75,7 @@ public static void SeedOperate(this Context context)
                 .StrictMode(true)
                 .RuleFor(o => o.Id, f => 0)
                 .RuleFor(o => o.Name, f => f.Commerce.ProductName())
-                .RuleFor(o => o.FileTypes, f => new string[] { f.System.CommonFileExt(), f.System.CommonFileExt() }.Distinct().ToArray())
+                .RuleFor(o => o.FileTypes, f => new string[] { "." + f.System.CommonFileExt(), "." + f.System.CommonFileExt() }.Distinct().ToArray())
                 .RuleFor(o => o.SpatialExtent, f => f.Address.GetExtent())
                 .RuleFor(o => o.Organisations, f => f.PickRandom(context.Organisations.ToList(), 1).ToList())
                 .RuleFor(o => o.Deliveries, _ => new List<Delivery>());
diff --git a/src/GeoCop.Api/Contracts/ValidationSettingsResponse.cs b/src/GeoCop.Api/Contracts/ValidationSettingsResponse.cs
new file mode 100644
index 00000000..07741000
--- /dev/null
+++ b/src/GeoCop.Api/Contracts/ValidationSettingsResponse.cs
@@ -0,0 +1,14 @@
+namespace GeoCop.Api.Contracts
+{
+    /// <summary>
+    /// The validation settings response schema.
+    /// </summary>
+    public class ValidationSettingsResponse
+    {
+        /// <summary>
+        /// File extensions that are allowed for upload.
+        /// All entries start with a "." like ".txt", ".xml" and the collection can include ".*" (all files allowed).
+        /// </summary>
+        public ICollection<string> AllowedFileExtensions { get; set; } = new List<string>();
+    }
+}
diff --git a/src/GeoCop.Api/Controllers/UploadController.cs b/src/GeoCop.Api/Controllers/UploadController.cs
index 20f48b91..5ec9cf27 100644
--- a/src/GeoCop.Api/Controllers/UploadController.cs
+++ b/src/GeoCop.Api/Controllers/UploadController.cs
@@ -1,4 +1,5 @@
 using Asp.Versioning;
+using GeoCop.Api.Contracts;
 using GeoCop.Api.Validation;
 using Microsoft.AspNetCore.Mvc;
 using Swashbuckle.AspNetCore.Annotations;
@@ -26,6 +27,20 @@ public UploadController(ILogger<UploadController> logger, IValidationService val
             this.validationService = validationService;
         }
 
+        /// <summary>
+        /// Returns the validation settings.
+        /// </summary>
+        /// <returns>Configuration settings for validations.</returns>
+        [HttpGet]
+        [SwaggerResponse(StatusCodes.Status200OK, "The specified settings for uploading files.", typeof(ValidationSettingsResponse), new[] { "application/json" })]
+        public async Task<IActionResult> GetValidationSettings()
+        {
+            return Ok(new ValidationSettingsResponse
+            {
+                AllowedFileExtensions = await validationService.GetSupportedFileExtensionsAsync(),
+            });
+        }
+
         /// <summary>
         /// Schedules a new job for the given <paramref name="file"/>.
         /// </summary>
@@ -73,6 +88,13 @@ public async Task<IActionResult> UploadAsync(ApiVersion version, IFormFile file)
         {
             if (file == null) return Problem($"Form data <{nameof(file)}> cannot be empty.", statusCode: StatusCodes.Status400BadRequest);
 
+            var fileExtension = Path.GetExtension(file.FileName);
+            if (!await validationService.IsFileExtensionSupportedAsync(fileExtension))
+            {
+                logger.LogTrace("File extension <{FileExtension}> is not supported.", fileExtension);
+                return Problem($"File extension <{fileExtension}> is not supported.", statusCode: StatusCodes.Status400BadRequest);
+            }
+
             var (validationJob, fileHandle) = validationService.CreateValidationJob(file.FileName);
             using (fileHandle)
             {
diff --git a/src/GeoCop.Api/Validation/IValidationService.cs b/src/GeoCop.Api/Validation/IValidationService.cs
index e81826c7..9a36d21a 100644
--- a/src/GeoCop.Api/Validation/IValidationService.cs
+++ b/src/GeoCop.Api/Validation/IValidationService.cs
@@ -32,5 +32,19 @@ public interface IValidationService
         /// <param name="jobId">The id of the validation job.</param>
         /// <returns>Status information for the validation job with the specified <paramref name="jobId"/>.</returns>
         ValidationJobStatus? GetJobStatus(Guid jobId);
+
+        /// <summary>
+        /// Gets all file extensions that are supported for upload.
+        /// All entries start with a "." like ".txt", ".xml" and the collection can include ".*" (all files allowed).
+        /// </summary>
+        /// <returns>Supported file extensions.</returns>
+        Task<ICollection<string>> GetSupportedFileExtensionsAsync();
+
+        /// <summary>
+        /// Checks if the specified <paramref name="fileExtension"/> is supported for upload.
+        /// </summary>
+        /// <param name="fileExtension">Extension of the uploaded file starting with ".".</param>
+        /// <returns>True, if the <paramref name="fileExtension"/> is supported.</returns>
+        Task<bool> IsFileExtensionSupportedAsync(string fileExtension);
     }
 }
diff --git a/src/GeoCop.Api/Validation/IValidator.cs b/src/GeoCop.Api/Validation/IValidator.cs
index 6d8a417d..0e8438ef 100644
--- a/src/GeoCop.Api/Validation/IValidator.cs
+++ b/src/GeoCop.Api/Validation/IValidator.cs
@@ -10,6 +10,11 @@ public interface IValidator
         /// </summary>
         string Name { get; }
 
+        /// <summary>
+        /// Gets the supported file extensions.
+        /// </summary>
+        Task<ICollection<string>> GetSupportedFileExtensionsAsync();
+
         /// <summary>
         /// Asynchronously validates the <paramref name="validationJob"/> specified.
         /// Its file must be accessible by an <see cref="IFileProvider"/> when executing this function.
diff --git a/src/GeoCop.Api/Validation/Interlis/IliCheckSettingsResponse.cs b/src/GeoCop.Api/Validation/Interlis/IliCheckSettingsResponse.cs
new file mode 100644
index 00000000..f0d4d12f
--- /dev/null
+++ b/src/GeoCop.Api/Validation/Interlis/IliCheckSettingsResponse.cs
@@ -0,0 +1,13 @@
+namespace GeoCop.Api.Validation.Interlis
+{
+    /// <summary>
+    /// Result of a settings query of interlis-check-service at /api/v1/settings.
+    /// </summary>
+    public class IliCheckSettingsResponse
+    {
+        /// <summary>
+        /// The accepted file types.
+        /// </summary>
+        public string? AcceptedFileTypes { get; set; }
+    }
+}
diff --git a/src/GeoCop.Api/Validation/Interlis/InterlisValidator.cs b/src/GeoCop.Api/Validation/Interlis/InterlisValidator.cs
index a62bb24f..f359ea66 100644
--- a/src/GeoCop.Api/Validation/Interlis/InterlisValidator.cs
+++ b/src/GeoCop.Api/Validation/Interlis/InterlisValidator.cs
@@ -12,12 +12,14 @@ namespace GeoCop.Api.Validation.Interlis
     public class InterlisValidator : IValidator
     {
         private const string UploadUrl = "/api/v1/upload";
+        private const string SettingsUrl = "/api/v1/settings";
         private static readonly TimeSpan pollInterval = TimeSpan.FromSeconds(2);
 
         private readonly ILogger<InterlisValidator> logger;
         private readonly IFileProvider fileProvider;
         private readonly HttpClient httpClient;
         private readonly JsonSerializerOptions jsonSerializerOptions;
+        private ICollection<string>? supportedFileExtensions;
 
         /// <inheritdoc/>
         public string Name => "ilicheck";
@@ -33,6 +35,17 @@ public InterlisValidator(ILogger<InterlisValidator> logger, IFileProvider filePr
             jsonSerializerOptions = jsonOptions.Value.JsonSerializerOptions;
         }
 
+        /// <inheritdoc/>
+        public async Task<ICollection<string>> GetSupportedFileExtensionsAsync()
+        {
+            if (supportedFileExtensions != null) return supportedFileExtensions;
+
+            var response = await httpClient.GetAsync(SettingsUrl).ConfigureAwait(false);
+            var configResult = await ReadSuccessResponseJsonAsync<IliCheckSettingsResponse>(response, CancellationToken.None).ConfigureAwait(false);
+            supportedFileExtensions = configResult.AcceptedFileTypes?.Split(", ");
+            return supportedFileExtensions ?? Array.Empty<string>();
+        }
+
         /// <inheritdoc/>
         public async Task<ValidatorResult> ExecuteAsync(ValidationJob validationJob, CancellationToken cancellationToken)
         {
diff --git a/src/GeoCop.Api/Validation/ValidationService.cs b/src/GeoCop.Api/Validation/ValidationService.cs
index 07e9cd06..25b65e86 100644
--- a/src/GeoCop.Api/Validation/ValidationService.cs
+++ b/src/GeoCop.Api/Validation/ValidationService.cs
@@ -8,15 +8,17 @@ public class ValidationService : IValidationService
         private readonly IFileProvider fileProvider;
         private readonly IValidationRunner validationRunner;
         private readonly IEnumerable<IValidator> validators;
+        private readonly Context context;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ValidationService"/> class.
         /// </summary>
-        public ValidationService(IFileProvider fileProvider, IValidationRunner validationRunner, IEnumerable<IValidator> validators)
+        public ValidationService(IFileProvider fileProvider, IValidationRunner validationRunner, IEnumerable<IValidator> validators, Context context)
         {
             this.fileProvider = fileProvider;
             this.validationRunner = validationRunner;
             this.validators = validators;
+            this.context = context;
         }
 
         /// <inheritdoc/>
@@ -34,7 +36,18 @@ public ValidationService(IFileProvider fileProvider, IValidationRunner validatio
         /// <inheritdoc/>
         public async Task<ValidationJobStatus> StartValidationJobAsync(ValidationJob validationJob)
         {
-            await validationRunner.EnqueueJobAsync(validationJob, validators);
+            var fileExtension = Path.GetExtension(validationJob.TempFileName);
+            var supportedValidators = new List<IValidator>();
+            foreach (var validator in validators)
+            {
+                var supportedExtensions = await validator.GetSupportedFileExtensionsAsync();
+                if (IsExtensionSupported(supportedExtensions, fileExtension))
+                {
+                    supportedValidators.Add(validator);
+                }
+            }
+
+            await validationRunner.EnqueueJobAsync(validationJob, supportedValidators);
             return GetJobStatus(validationJob.Id) ?? throw new InvalidOperationException("The validation job was not enqueued.");
         }
 
@@ -49,5 +62,51 @@ public async Task<ValidationJobStatus> StartValidationJobAsync(ValidationJob val
         {
             return validationRunner.GetJobStatus(jobId);
         }
+
+        /// <inheritdoc/>
+        public async Task<ICollection<string>> GetSupportedFileExtensionsAsync()
+        {
+            var mandateFileExtensions = GetFileExtensionsForDeliveryMandates();
+            var validatorFileExtensions = await GetFileExtensionsForValidatorsAsync();
+
+            return mandateFileExtensions
+                .Union(validatorFileExtensions)
+                .OrderBy(ext => ext)
+                .ToList();
+        }
+
+        /// <inheritdoc/>
+        public async Task<bool> IsFileExtensionSupportedAsync(string fileExtension)
+        {
+            var extensions = await GetSupportedFileExtensionsAsync();
+            return IsExtensionSupported(extensions, fileExtension);
+        }
+
+        private HashSet<string> GetFileExtensionsForDeliveryMandates()
+        {
+            return context.DeliveryMandates
+                .Select(mandate => mandate.FileTypes)
+                .AsEnumerable()
+                .SelectMany(ext => ext)
+                .Select(ext => ext.ToLowerInvariant())
+                .ToHashSet();
+        }
+
+        private async Task<HashSet<string>> GetFileExtensionsForValidatorsAsync()
+        {
+            var tasks = validators.Select(validator => validator.GetSupportedFileExtensionsAsync());
+
+            var validatorFileExtensions = await Task.WhenAll(tasks);
+
+            return validatorFileExtensions
+                .SelectMany(ext => ext)
+                .Select(ext => ext.ToLowerInvariant())
+                .ToHashSet();
+        }
+
+        private static bool IsExtensionSupported(ICollection<string> supportedExtensions, string fileExtension)
+        {
+            return supportedExtensions.Any(ext => ext == ".*" || string.Equals(ext, fileExtension, StringComparison.OrdinalIgnoreCase));
+        }
     }
 }
diff --git a/src/GeoCop.Frontend/src/FileDropzone.jsx b/src/GeoCop.Frontend/src/FileDropzone.jsx
index f0a32777..d90c5a29 100644
--- a/src/GeoCop.Frontend/src/FileDropzone.jsx
+++ b/src/GeoCop.Frontend/src/FileDropzone.jsx
@@ -48,13 +48,13 @@ export const FileDropzone = ({
   const [dropZoneText, setDropZoneText] = useState(dropZoneDefaultText);
   const [dropZoneTextClass, setDropZoneTextClass] = useState("dropzone dropzone-text-disabled");
 
-  useEffect(
-    () =>
-      setDropZoneDefaultText(
-        `Datei (${acceptedFileTypes}) hier ablegen oder klicken um vom lokalen Dateisystem auszuwählen.`,
-      ),
-    [acceptedFileTypes],
-  );
+  const acceptsAllFileTypes = acceptedFileTypes?.includes(".*") ?? false;
+  const acceptedFileTypesText = acceptedFileTypes?.join(", ") ?? "";
+
+  useEffect(() => {
+    const fileDescription = acceptsAllFileTypes ? "Datei" : `Datei (${acceptedFileTypesText})`;
+    setDropZoneDefaultText(`${fileDescription} hier ablegen oder klicken um vom lokalen Dateisystem auszuwählen.`);
+  }, [acceptsAllFileTypes, acceptedFileTypesText]);
   useEffect(() => setDropZoneText(dropZoneDefaultText), [dropZoneDefaultText]);
 
   const onDropAccepted = useCallback(
@@ -87,12 +87,13 @@ export const FileDropzone = ({
     (fileRejections) => {
       setDropZoneTextClass("dropzone dropzone-text-error");
       const errorCode = fileRejections[0].errors[0].code;
+      const genericError =
+        "Bitte wähle eine Datei (max. 200MB)" +
+        (acceptsAllFileTypes ? "" : ` mit einer der folgenden Dateiendungen: ${acceptedFileTypesText}`);
 
       switch (errorCode) {
         case "file-invalid-type":
-          setDropZoneText(
-            `Der Dateityp wird nicht unterstützt. Bitte wähle eine Datei (max. 200MB) mit einer der folgenden Dateiendungen: ${acceptedFileTypes}`,
-          );
+          setDropZoneText(`Der Dateityp wird nicht unterstützt. ${genericError}`);
           break;
         case "too-many-files":
           setDropZoneText("Es kann nur eine Datei aufs Mal geprüft werden.");
@@ -103,14 +104,13 @@ export const FileDropzone = ({
           );
           break;
         default:
-          setDropZoneText(
-            `Bitte wähle eine Datei (max. 200MB) mit einer der folgenden Dateiendungen: ${acceptedFileTypes}`,
-          );
+          setDropZoneText(genericError);
+          break;
       }
       resetFileToCheck();
       setFileAvailable(false);
     },
-    [resetFileToCheck, acceptedFileTypes],
+    [resetFileToCheck, acceptsAllFileTypes, acceptedFileTypesText],
   );
 
   const removeFile = (e) => {
@@ -122,12 +122,17 @@ export const FileDropzone = ({
     setDropZoneTextClass("dropzone dropzone-text-disabled");
   };
 
+  const accept = acceptsAllFileTypes
+    ? undefined
+    : {
+        "application/x-geocop-files": acceptedFileTypes ?? [],
+      };
   const { getRootProps, getInputProps, isDragActive } = useDropzone({
     onDropAccepted,
     onDropRejected,
     maxFiles: 1,
     maxSize: 209715200,
-    accept: acceptedFileTypes,
+    accept,
   });
 
   return (
diff --git a/src/GeoCop.Frontend/src/Home.jsx b/src/GeoCop.Frontend/src/Home.jsx
index 44b76eef..02114951 100644
--- a/src/GeoCop.Frontend/src/Home.jsx
+++ b/src/GeoCop.Frontend/src/Home.jsx
@@ -22,6 +22,13 @@ export const Home = ({
   const [log, setLog] = useState([]);
   const [uploadLogsInterval, setUploadLogsInterval] = useState(0);
   const [uploadLogsEnabled, setUploadLogsEnabled] = useState(false);
+  const [uploadSettings, setUploadSettings] = useState({});
+
+  useEffect(() => {
+    fetch("/api/v1/upload")
+      .then((res) => res.headers.get("content-type")?.includes("application/json") && res.json())
+      .then((settings) => setUploadSettings(settings));
+  }, []);
 
   // Enable Upload logging
   useEffect(() => {
@@ -131,7 +138,7 @@ export const Home = ({
           validationRunning={validationRunning}
           setCheckedNutzungsbestimmungen={setCheckedNutzungsbestimmungen}
           showNutzungsbestimmungen={showNutzungsbestimmungen}
-          acceptedFileTypes={clientSettings?.acceptedFileTypes}
+          acceptedFileTypes={uploadSettings?.allowedFileExtensions}
           fileToCheckRef={fileToCheckRef}
         />
       </Container>
diff --git a/tests/GeoCop.Api.Test/UploadControllerTest.cs b/tests/GeoCop.Api.Test/UploadControllerTest.cs
index 7d8b93cc..39eaaa2d 100644
--- a/tests/GeoCop.Api.Test/UploadControllerTest.cs
+++ b/tests/GeoCop.Api.Test/UploadControllerTest.cs
@@ -51,9 +51,10 @@ public async Task UploadAsync()
             var validationJob = new ValidationJob(jobId, originalFileName, "TEMP.xtf");
             using var fileHandle = new FileHandle(validationJob.TempFileName, Stream.Null);
 
-            validationServiceMock.Setup(x => x.CreateValidationJob(It.Is<string>(x => x == originalFileName))).Returns((validationJob, fileHandle));
+            validationServiceMock.Setup(x => x.IsFileExtensionSupportedAsync(".xtf")).Returns(Task.FromResult(true));
+            validationServiceMock.Setup(x => x.CreateValidationJob(originalFileName)).Returns((validationJob, fileHandle));
             validationServiceMock
-                .Setup(x => x.StartValidationJobAsync(It.Is<ValidationJob>(x => x == validationJob)))
+                .Setup(x => x.StartValidationJobAsync(validationJob))
                 .Returns(Task.FromResult(new ValidationJobStatus(jobId)));
 
             var response = await controller.UploadAsync(apiVersionMock.Object, formFileMock.Object) as CreatedResult;
@@ -74,5 +75,19 @@ public async Task UploadAsyncForNull()
             Assert.AreEqual(StatusCodes.Status400BadRequest, response!.StatusCode);
             Assert.AreEqual("Form data <file> cannot be empty.", ((ProblemDetails)response.Value!).Detail);
         }
+
+        [TestMethod]
+        public async Task UploadInvalidFileExtension()
+        {
+            formFileMock.SetupGet(x => x.FileName).Returns("upload.exe");
+
+            validationServiceMock.Setup(x => x.IsFileExtensionSupportedAsync(".exe")).Returns(Task.FromResult(false));
+
+            var response = await controller.UploadAsync(apiVersionMock.Object, formFileMock.Object) as ObjectResult;
+
+            Assert.IsInstanceOfType(response, typeof(ObjectResult));
+            Assert.AreEqual(StatusCodes.Status400BadRequest, response!.StatusCode);
+            Assert.AreEqual("File extension <.exe> is not supported.", ((ProblemDetails)response.Value!).Detail);
+        }
     }
 }
diff --git a/tests/GeoCop.Api.Test/Validation/ValidationServiceTest.cs b/tests/GeoCop.Api.Test/Validation/ValidationServiceTest.cs
index 110641d2..1d6eeb93 100644
--- a/tests/GeoCop.Api.Test/Validation/ValidationServiceTest.cs
+++ b/tests/GeoCop.Api.Test/Validation/ValidationServiceTest.cs
@@ -1,4 +1,5 @@
-using Moq;
+using Microsoft.EntityFrameworkCore;
+using Moq;
 
 namespace GeoCop.Api.Validation
 {
@@ -8,6 +9,7 @@ public class ValidationServiceTest
         private Mock<IFileProvider> fileProviderMock;
         private Mock<IValidationRunner> validationRunnerMock;
         private Mock<IValidator> validatorMock;
+        private Mock<Context> contextMock;
         private ValidationService validationService;
 
         [TestInitialize]
@@ -16,11 +18,13 @@ public void Initialize()
             fileProviderMock = new Mock<IFileProvider>(MockBehavior.Strict);
             validationRunnerMock = new Mock<IValidationRunner>(MockBehavior.Strict);
             validatorMock = new Mock<IValidator>(MockBehavior.Strict);
+            contextMock = new Mock<Context>(new DbContextOptions<Context>());
 
             validationService = new ValidationService(
                 fileProviderMock.Object,
                 validationRunnerMock.Object,
-                new[] { validatorMock.Object });
+                new[] { validatorMock.Object },
+                contextMock.Object);
         }
 
         [TestCleanup]