diff --git a/src/GitHubActionsDemo.Api/Controllers/AuthorsController.cs b/src/GitHubActionsDemo.Api/Controllers/AuthorsController.cs
index 2fcde26..91f639a 100644
--- a/src/GitHubActionsDemo.Api/Controllers/AuthorsController.cs
+++ b/src/GitHubActionsDemo.Api/Controllers/AuthorsController.cs
@@ -1,7 +1,9 @@
+using System.Runtime.Intrinsics.X86;
 using GitHubActionsDemo.Api.Models;
 using GitHubActionsDemo.Api.Mappers;
 using GitHubActionsDemo.Service;
 using Microsoft.AspNetCore.Mvc;
+using FluentValidation;
 
 namespace GitHubActionsDemo.Api.Controllers;
 
@@ -10,42 +12,59 @@ namespace GitHubActionsDemo.Api.Controllers;
 public class AuthorsController : BaseController
 {
     private readonly ILibraryService _libraryService;
+    private readonly IValidator<AuthorRequest> _authorValidator;
+    private readonly IValidator<PageParameters> _pageValidator;
 
     public AuthorsController(
-        ILibraryService libraryService
+        ILibraryService libraryService,
+        IValidator<AuthorRequest> authorValidator,
+        IValidator<PageParameters> pageValidator
     )
     {
         _libraryService = libraryService ?? throw new ArgumentNullException(nameof(libraryService));
+        _authorValidator = authorValidator ?? throw new ArgumentNullException(nameof(authorValidator));
+        _pageValidator = pageValidator ?? throw new ArgumentNullException(nameof(pageValidator));
     }
 
     [HttpPost]
-    public async Task<IActionResult> AddAuthorAsync([FromBody] AuthorRequest authorRequest)
+    public async Task<IResult> AddAuthorAsync([FromBody] AuthorRequest authorRequest)
     {
+        var validationResult = await _authorValidator.ValidateAsync(authorRequest);
+
+        if (!validationResult.IsValid)
+            return Results.ValidationProblem(validationResult.ToDictionary());
+
+
         var result = await _libraryService.AddAuthorAsync(authorRequest.Map());
         return result.Match(
-            success => Ok(success.Value.Map()),
+            success => Results.Ok(success.Value.Map()),
             error => InternalError()
         );
     }
 
     [HttpGet("{authorId}")]
-    public async Task<IActionResult> GetAuthorAsync(int authorId)
+    public async Task<IResult> GetAuthorAsync(int authorId)
     {
         var result = await _libraryService.GetAuthorAsync(authorId);
         return result.Match(
-            success => Ok(success.Value.Map()),
-            notfound => NotFound(),
+            success => Results.Ok(success.Value.Map()),
+            notfound => Results.NotFound(),
             error => InternalError()
         );
     }
 
     [HttpGet]
-    public async Task<IActionResult> GetAuthorsAsync([FromQuery(Name = "page")] int page = 1, [FromQuery(Name = "pageSize")] int pageSize = 10)
+    public async Task<IResult> GetAuthorsAsync([FromQuery] PageParameters parameters)
     {
-        var result = await _libraryService.GetAuthorsAsync(page, pageSize);
+        var validationResult = await _pageValidator.ValidateAsync(parameters);
+
+        if (!validationResult.IsValid)
+            return Results.ValidationProblem(validationResult.ToDictionary());
+
+        var result = await _libraryService.GetAuthorsAsync(parameters.Page, parameters.PageSize);
 
         return result.Match(
-            success => PagedResult(page, pageSize, success.Value.Select(x => x.Map()).ToList()),
+            success => PagedResult(parameters.Page, parameters.PageSize, success.Value.Select(x => x.Map()).ToList()),
             error => InternalError()
         );
     }
diff --git a/src/GitHubActionsDemo.Api/Controllers/BaseController.cs b/src/GitHubActionsDemo.Api/Controllers/BaseController.cs
index 857a05e..7cb2fe8 100644
--- a/src/GitHubActionsDemo.Api/Controllers/BaseController.cs
+++ b/src/GitHubActionsDemo.Api/Controllers/BaseController.cs
@@ -7,13 +7,13 @@ namespace GitHubActionsDemo.Api.Controllers;
 
 public class BaseController : ControllerBase
 {
-    public IActionResult InternalError()
+    public IResult InternalError()
     {
-        return new StatusCodeResult((int)HttpStatusCode.InternalServerError);
+        return Results.StatusCode((int)HttpStatusCode.InternalServerError);
     }
 
-    public IActionResult PagedResult<T>(int page, int pageSize, T result) where T : IList
+    public IResult PagedResult<T>(int page, int pageSize, T result) where T : IList
     {
-        return Ok(new PagedResponse<T>(page, pageSize, result));
+        return Results.Ok(new PagedResponse<T>(page, pageSize, result));
     }
 }
\ No newline at end of file
diff --git a/src/GitHubActionsDemo.Api/Controllers/BooksController.cs b/src/GitHubActionsDemo.Api/Controllers/BooksController.cs
index dea4b18..b7bb018 100644
--- a/src/GitHubActionsDemo.Api/Controllers/BooksController.cs
+++ b/src/GitHubActionsDemo.Api/Controllers/BooksController.cs
@@ -2,6 +2,7 @@ using GitHubActionsDemo.Api.Models;
 using GitHubActionsDemo.Api.Mappers;
 using GitHubActionsDemo.Service;
 using Microsoft.AspNetCore.Mvc;
+using FluentValidation;
 
 namespace GitHubActionsDemo.Api.Controllers;
 
@@ -10,42 +11,58 @@ namespace GitHubActionsDemo.Api.Controllers;
 public class BooksController : BaseController
 {
     private readonly ILibraryService _libraryService;
+    private readonly IValidator<BookRequest> _bookValidator;
+    private readonly IValidator<PageParameters> _pageValidator;
 
     public BooksController(
-        ILibraryService libraryService
+        ILibraryService libraryService,
+        IValidator<BookRequest> bookValidator,
+        IValidator<PageParameters> pageValidator
     )
     {
         _libraryService = libraryService ?? throw new ArgumentNullException(nameof(libraryService));
+        _bookValidator = bookValidator ?? throw new ArgumentNullException(nameof(bookValidator));
+        _pageValidator = pageValidator ?? throw new ArgumentNullException(nameof(pageValidator));
     }
 
     [HttpGet]
-    public async Task<IActionResult> GetBooksAsync([FromQuery(Name = "page")] int page = 1, [FromQuery(Name = "pageSize")] int pageSize = 10)
+    public async Task<IResult> GetBooksAsync([FromQuery] PageParameters parameters)
     {
-        var result = await _libraryService.GetBooksAsync(page, pageSize);
+        var validationResult = await _pageValidator.ValidateAsync(parameters);
+
+        if (!validationResult.IsValid)
+            return Results.ValidationProblem(validationResult.ToDictionary());
+
+        var result = await _libraryService.GetBooksAsync(parameters.Page, parameters.PageSize);
 
         return result.Match(
-            success => PagedResult(page, pageSize, success.Value.Select(x => x.Map()).ToList()),
+            success => PagedResult(parameters.Page, parameters.PageSize, success.Value.Select(x => x.Map()).ToList()),
             error => InternalError()
         );
     }
 
     [HttpGet("{bookId}")]
-    public async Task<IActionResult> GetBookAsync(int bookId)
+    public async Task<IResult> GetBookAsync(int bookId)
     {
         var result = await _libraryService.GetBookAsync(bookId);
         return result.Match(
-            success => Ok(success.Value.Map()),
-            notfound => NotFound(),
+            success => Results.Ok(success.Value.Map()),
+            notfound => Results.NotFound(),
             error => InternalError()
         );
     }
 
     [HttpPost]
-    public async Task<IActionResult> AddBookAsync([FromBody] BookRequest bookRequest)
+    public async Task<IResult> AddBookAsync([FromBody] BookRequest bookRequest)
     {
+        var validationResult = await _bookValidator.ValidateAsync(bookRequest);
+
+        if (!validationResult.IsValid)
+            return Results.ValidationProblem(validationResult.ToDictionary());
+
         var result = await _libraryService.AddBookAsync(bookRequest.Map());
         return result.Match(
-            success => Ok(success.Value.Map()),
+            success => Results.Ok(success.Value.Map()),
             error => InternalError()
         );
     }
diff --git a/src/GitHubActionsDemo.Api/GitHubActionsDemo.Api.csproj b/src/GitHubActionsDemo.Api/GitHubActionsDemo.Api.csproj
index 1cb6438..c48f0b4 100644
--- a/src/GitHubActionsDemo.Api/GitHubActionsDemo.Api.csproj
+++ b/src/GitHubActionsDemo.Api/GitHubActionsDemo.Api.csproj
@@ -8,6 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="FluentValidation" Version="11.5.2" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="7.0.5" />
     <PackageReference Include="OneOf" Version="3.0.255" />
     <PackageReference Include="Serilog" Version="3.0.1" />
diff --git a/src/GitHubActionsDemo.Api/Models/PageParameters.cs b/src/GitHubActionsDemo.Api/Models/PageParameters.cs
new file mode 100644
index 0000000..c48337b
--- /dev/null
+++ b/src/GitHubActionsDemo.Api/Models/PageParameters.cs
@@ -0,0 +1,7 @@
+namespace GitHubActionsDemo.Api.Models;
+
+public class PageParameters
+{
+    public int Page { get; set; } = 1;
+    public int PageSize { get; set; } = 10;
+}
\ No newline at end of file
diff --git a/src/GitHubActionsDemo.Api/Models/Validators/AuthorRequestValidator.cs b/src/GitHubActionsDemo.Api/Models/Validators/AuthorRequestValidator.cs
new file mode 100644
index 0000000..8fa3824
--- /dev/null
+++ b/src/GitHubActionsDemo.Api/Models/Validators/AuthorRequestValidator.cs
@@ -0,0 +1,12 @@
+using FluentValidation;
+
+namespace GitHubActionsDemo.Api.Models.Validators;
+
+public class AuthorRequestValidator : AbstractValidator<AuthorRequest>
+{
+    public AuthorRequestValidator()
+    {
+        RuleFor(x => x.FirstName).NotEmpty();
+        RuleFor(x => x.LastName).NotEmpty();
+    }
+}
\ No newline at end of file
diff --git a/src/GitHubActionsDemo.Api/Models/Validators/BookRequestValidator.cs b/src/GitHubActionsDemo.Api/Models/Validators/BookRequestValidator.cs
new file mode 100644
index 0000000..84a6d31
--- /dev/null
+++ b/src/GitHubActionsDemo.Api/Models/Validators/BookRequestValidator.cs
@@ -0,0 +1,21 @@
+using FluentValidation;
+
+namespace GitHubActionsDemo.Api.Models.Validators;
+
+public class BookRequestValidator : AbstractValidator<BookRequest>
+{
+    public BookRequestValidator()
+    {
+        RuleFor(x => x.Title).NotEmpty();
+        RuleFor(x => x.AuthorId).NotEmpty();
+
+        RuleFor(x => x.Isbn)
+            .NotEmpty()
+            .MinimumLength(10)
+            .MaximumLength(17)
+            .Matches(@"^(?:ISBN(?:-1[03])?:? )?(?=[0-9X]{10}$|(?=(?:[0-9]+[- ]){3})[- 0 - 9X]{ 13}$| 97[89][0 - 9]{ 10}$| (?= (?:[0 - 9] +[- ]){ 4})[- 0 - 9]{ 17}$)(?: 97[89][- ] ?)?[0 - 9]{ 1,5}[- ]?[0 - 9]+[- ]?[0 - 9] +[- ]?[0 - 9X]$");
+
+        RuleFor(x => x.DatePublished)
+            .NotEmpty();
+    }
+}
\ No newline at end of file
diff --git a/src/GitHubActionsDemo.Api/Models/Validators/PageParametersValidator.cs b/src/GitHubActionsDemo.Api/Models/Validators/PageParametersValidator.cs
new file mode 100644
index 0000000..dac0bf7
--- /dev/null
+++ b/src/GitHubActionsDemo.Api/Models/Validators/PageParametersValidator.cs
@@ -0,0 +1,12 @@
+using FluentValidation;
+
+namespace GitHubActionsDemo.Api.Models.Validators;
+
+public class PageParametersValidator : AbstractValidator<PageParameters>
+{
+    public PageParametersValidator()
+    {
+        RuleFor(x => x.Page).GreaterThan(0);
+        RuleFor(x => x.PageSize).InclusiveBetween(1, 100);
+    }
+}
\ No newline at end of file
diff --git a/src/GitHubActionsDemo.Api/Program.cs b/src/GitHubActionsDemo.Api/Program.cs
index 6b9e4ac..090a4b7 100644
--- a/src/GitHubActionsDemo.Api/Program.cs
+++ b/src/GitHubActionsDemo.Api/Program.cs
@@ -1,6 +1,9 @@
 using GitHubActionsDemo.Service.Infrastructure;
 using GitHubActionsDemo.Persistance.Infrastructure;
 using Serilog;
+using FluentValidation;
+using GitHubActionsDemo.Api.Models;
+using GitHubActionsDemo.Api.Models.Validators;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -10,6 +13,10 @@ var logger = new LoggerConfiguration()
     .CreateLogger();
 builder.Logging.AddSerilog(logger);
 
+builder.Services.AddScoped<IValidator<AuthorRequest>, AuthorRequestValidator>();
+builder.Services.AddScoped<IValidator<BookRequest>, BookRequestValidator>();
+builder.Services.AddScoped<IValidator<PageParameters>, PageParametersValidator>();
+
 builder.Services.AddControllers();
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen();