diff --git a/api/src/BaseClasses/BaseController.cs b/api/src/BaseClasses/BaseController.cs
index dc09d65..83cb0c7 100644
--- a/api/src/BaseClasses/BaseController.cs
+++ b/api/src/BaseClasses/BaseController.cs
@@ -5,14 +5,14 @@ namespace WinStudentGoalTracker.BaseClasses;
 
 public class BaseController : ControllerBase
 {
-    protected (int userId, ActionResult? error) GetUserIdFromClaims()
+    protected (Guid userId, ActionResult? error) GetUserIdFromClaims()
     {
         var userIdClaim = User.FindFirst("user_id")?.Value
             ?? User.FindFirst(ClaimTypes.NameIdentifier)?.Value;
 
-        if (string.IsNullOrWhiteSpace(userIdClaim) || !int.TryParse(userIdClaim, out var userId))
+        if (string.IsNullOrWhiteSpace(userIdClaim) || !Guid.TryParse(userIdClaim, out var userId))
         {
-            return (0, Unauthorized("Missing or invalid user_id claim."));
+            return (Guid.Empty, Unauthorized("Missing or invalid user_id claim."));
         }
 
         return (userId, null);
diff --git a/api/src/Controllers/AuthController.cs b/api/src/Controllers/AuthController.cs
index a4e5488..e3980e1 100644
--- a/api/src/Controllers/AuthController.cs
+++ b/api/src/Controllers/AuthController.cs
@@ -87,6 +87,7 @@ public class AuthController : BaseController
 
         // Store refresh token in database (30 days expiration)
         var refreshTokenId = await _authRepo.CreateRefreshTokenAsync(
+            Guid.NewGuid(),
             user.IdUser,
             refreshTokenHash,
             refreshTokenSalt,
@@ -151,7 +152,7 @@ public class AuthController : BaseController
         var tokenIdStr = refreshTokenDto.RefreshToken[..dotIndex];
         var secretToken = refreshTokenDto.RefreshToken[(dotIndex + 1)..];
 
-        if (!int.TryParse(tokenIdStr, out int tokenId))
+        if (!Guid.TryParse(tokenIdStr, out Guid tokenId))
         {
             return BadRequest(new ResponseResult<TokenRefreshResponse>
             {
@@ -221,6 +222,7 @@ public class AuthController : BaseController
 
         var newRefreshTokenId = await _authRepo.ReplaceRefreshTokenAsync(
             matchedToken.IdRefreshToken,
+            Guid.NewGuid(),
             tokenUser.IdUser,
             newRefreshTokenHash,
             newRefreshTokenSalt,
@@ -272,7 +274,7 @@ public class AuthController : BaseController
         if (error != null) return error;
 
         var dotIndex = logoutDto.RefreshToken.IndexOf('.');
-        if (dotIndex < 1 || !int.TryParse(logoutDto.RefreshToken[..dotIndex], out int tokenId))
+        if (dotIndex < 1 || !Guid.TryParse(logoutDto.RefreshToken[..dotIndex], out Guid tokenId))
         {
             return BadRequest(new ResponseResult<object>
             {
diff --git a/api/src/Controllers/StudentController.cs b/api/src/Controllers/StudentController.cs
index 57c78f8..1cac137 100644
--- a/api/src/Controllers/StudentController.cs
+++ b/api/src/Controllers/StudentController.cs
@@ -29,10 +29,10 @@ public class StudentController : BaseController
         });
     }
 
-    [HttpGet("{idStudent:int}")]
+    [HttpGet("{idStudent:guid}")]
     [ProducesResponseType(typeof(ResponseResult<StudentResponse>), StatusCodes.Status200OK)]
     [ProducesResponseType(typeof(ResponseResult<StudentResponse>), StatusCodes.Status404NotFound)]
-    public async Task<ActionResult<ResponseResult<StudentResponse>>> GetById(int idStudent)
+    public async Task<ActionResult<ResponseResult<StudentResponse>>> GetById(Guid idStudent)
     {
         var student = await _studentRepository.GetByIdAsync(idStudent);
         if (student is null)
@@ -84,10 +84,10 @@ public class StudentController : BaseController
         });
     }
 
-    [HttpPut("{idStudent:int}")]
+    [HttpPut("{idStudent:guid}")]
     [ProducesResponseType(typeof(ResponseResult<StudentResponse>), StatusCodes.Status200OK)]
     [ProducesResponseType(typeof(ResponseResult<StudentResponse>), StatusCodes.Status404NotFound)]
-    public async Task<ActionResult<ResponseResult<StudentResponse>>> Update(int idStudent, [FromBody] UpdateStudentDto request)
+    public async Task<ActionResult<ResponseResult<StudentResponse>>> Update(Guid idStudent, [FromBody] UpdateStudentDto request)
     {
         var existing = await _studentRepository.GetByIdAsync(idStudent);
         if (existing is null)
@@ -118,10 +118,10 @@ public class StudentController : BaseController
         });
     }
 
-    [HttpDelete("{idStudent:int}")]
+    [HttpDelete("{idStudent:guid}")]
     [ProducesResponseType(typeof(ResponseResult<object>), StatusCodes.Status200OK)]
     [ProducesResponseType(typeof(ResponseResult<object>), StatusCodes.Status404NotFound)]
-    public async Task<ActionResult<ResponseResult<object>>> Delete(int idStudent)
+    public async Task<ActionResult<ResponseResult<object>>> Delete(Guid idStudent)
     {
         var deleted = await _studentRepository.DeleteAsync(idStudent);
         if (!deleted)
diff --git a/api/src/DataAccess/Models/DataTransferObjects/CreateStudentDto.cs b/api/src/DataAccess/Models/DataTransferObjects/CreateStudentDto.cs
index a958b9b..b0e1c19 100644
--- a/api/src/DataAccess/Models/DataTransferObjects/CreateStudentDto.cs
+++ b/api/src/DataAccess/Models/DataTransferObjects/CreateStudentDto.cs
@@ -2,8 +2,8 @@ namespace WinStudentGoalTracker.DataAccess;
 
 public class CreateStudentDto
 {
-    public required int IdStudent { get; set; }
-    public int? IdProgram { get; set; }
+    public required Guid IdStudent { get; set; }
+    public Guid? IdProgram { get; set; }
     public string? Identifier { get; set; }
     public int? ProgramYear { get; set; }
     public DateTime? EnrollmentDate { get; set; }
diff --git a/api/src/DataAccess/Models/DataTransferObjects/UpdateStudentDto.cs b/api/src/DataAccess/Models/DataTransferObjects/UpdateStudentDto.cs
index 212fde7..fa721cc 100644
--- a/api/src/DataAccess/Models/DataTransferObjects/UpdateStudentDto.cs
+++ b/api/src/DataAccess/Models/DataTransferObjects/UpdateStudentDto.cs
@@ -2,7 +2,7 @@ namespace WinStudentGoalTracker.DataAccess;
 
 public class UpdateStudentDto
 {
-    public int? IdProgram { get; set; }
+    public Guid? IdProgram { get; set; }
     public string? Identifier { get; set; }
     public int? ProgramYear { get; set; }
     public DateTime? EnrollmentDate { get; set; }
diff --git a/api/src/DataAccess/Models/DatabaseObjects/dbRefreshToken.cs b/api/src/DataAccess/Models/DatabaseObjects/dbRefreshToken.cs
index ea9dd95..c54c65e 100644
--- a/api/src/DataAccess/Models/DatabaseObjects/dbRefreshToken.cs
+++ b/api/src/DataAccess/Models/DatabaseObjects/dbRefreshToken.cs
@@ -2,8 +2,8 @@ namespace WinStudentGoalTracker.DataAccess;
 
 public class dbRefreshToken
 {
-    public int IdRefreshToken { get; set; }
-    public int IdUser { get; set; }
+    public Guid IdRefreshToken { get; set; }
+    public Guid IdUser { get; set; }
     public required string TokenHash { get; set; }
     public required string TokenSalt { get; set; }
     public DateTime ExpiresAt { get; set; }
@@ -11,7 +11,7 @@ public class dbRefreshToken
     public DateTime? RevokedAt { get; set; }
     public string? DeviceInfo { get; set; }
     public string? UserAgent { get; set; }
-    public int? ReplacedByTokenId { get; set; }
+    public Guid? ReplacedByTokenId { get; set; }
     public DateTime CreatedAt { get; set; }
     public DateTime UpdatedAt { get; set; }
 }
diff --git a/api/src/DataAccess/Models/DatabaseObjects/dbStudent.cs b/api/src/DataAccess/Models/DatabaseObjects/dbStudent.cs
index 8a5b50e..0f87a9b 100644
--- a/api/src/DataAccess/Models/DatabaseObjects/dbStudent.cs
+++ b/api/src/DataAccess/Models/DatabaseObjects/dbStudent.cs
@@ -2,8 +2,8 @@ namespace WinStudentGoalTracker.DataAccess;
 
 public class dbStudent
 {
-    public required int IdStudent { get; set; }
-    public int? IdProgram { get; set; }
+    public required Guid IdStudent { get; set; }
+    public Guid? IdProgram { get; set; }
     public string? Identifier { get; set; }
     public int? ProgramYear { get; set; }
     public DateTime? EnrollmentDate { get; set; }
diff --git a/api/src/DataAccess/Models/DatabaseObjects/dbUser.cs b/api/src/DataAccess/Models/DatabaseObjects/dbUser.cs
index f2a56f0..c37abb4 100644
--- a/api/src/DataAccess/Models/DatabaseObjects/dbUser.cs
+++ b/api/src/DataAccess/Models/DatabaseObjects/dbUser.cs
@@ -2,8 +2,8 @@ namespace WinStudentGoalTracker.DataAccess;
 
 public class dbUser
 {
-    public required int IdUser { get; set; }
-    public int? IdRole { get; set; }
+    public required Guid IdUser { get; set; }
+    public Guid? IdRole { get; set; }
     public string? Email { get; set; }
     public string? Name { get; set; }
     public string? PasswordHash { get; set; }
diff --git a/api/src/DataAccess/Repositories/AuthRepository.cs b/api/src/DataAccess/Repositories/AuthRepository.cs
index d4b5f85..cad3d48 100644
--- a/api/src/DataAccess/Repositories/AuthRepository.cs
+++ b/api/src/DataAccess/Repositories/AuthRepository.cs
@@ -8,8 +8,9 @@ public class AuthRepository
 {
     private IDbConnection Connection => new MySqlConnection(DatabaseManager.ConnectionString);
 
-    public async Task<int?> CreateRefreshTokenAsync(
-        int userId,
+    public async Task<Guid?> CreateRefreshTokenAsync(
+        Guid refreshTokenId,
+        Guid userId,
         string tokenHash,
         string tokenSalt,
         int expiresInSeconds,
@@ -17,11 +18,12 @@ public class AuthRepository
         string? userAgent)
     {
         using var db = Connection;
-        return await db.QuerySingleOrDefaultAsync<int?>(
+        var result = await db.QuerySingleOrDefaultAsync<string?>(
             "sp_RefreshToken_Create",
             new
             {
-                p_id_user = userId,
+                p_id_refresh_token = refreshTokenId.ToString(),
+                p_id_user = userId.ToString(),
                 p_token_hash = tokenHash,
                 p_token_salt = tokenSalt,
                 p_expires_in_seconds = expiresInSeconds,
@@ -29,30 +31,32 @@ public class AuthRepository
                 p_user_agent = userAgent
             },
             commandType: CommandType.StoredProcedure);
+        return result != null ? Guid.Parse(result) : null;
     }
 
-    public async Task<dbRefreshToken?> GetRefreshTokenByIdAsync(int refreshTokenId)
+    public async Task<dbRefreshToken?> GetRefreshTokenByIdAsync(Guid refreshTokenId)
     {
         using var db = Connection;
         return await db.QuerySingleOrDefaultAsync<dbRefreshToken>(
             "sp_RefreshToken_GetById",
-            new { p_id_refresh_token = refreshTokenId },
+            new { p_id_refresh_token = refreshTokenId.ToString() },
             commandType: CommandType.StoredProcedure);
     }
 
-    public async Task<bool> RevokeRefreshTokenAsync(int refreshTokenId)
+    public async Task<bool> RevokeRefreshTokenAsync(Guid refreshTokenId)
     {
         using var db = Connection;
         var rowsAffected = await db.QuerySingleOrDefaultAsync<int>(
             "sp_RefreshToken_Revoke",
-            new { p_id_refresh_token = refreshTokenId },
+            new { p_id_refresh_token = refreshTokenId.ToString() },
             commandType: CommandType.StoredProcedure);
         return rowsAffected > 0;
     }
 
-    public async Task<int?> ReplaceRefreshTokenAsync(
-        int oldTokenId,
-        int userId,
+    public async Task<Guid?> ReplaceRefreshTokenAsync(
+        Guid oldTokenId,
+        Guid newTokenId,
+        Guid userId,
         string tokenHash,
         string tokenSalt,
         int expiresInSeconds,
@@ -60,12 +64,13 @@ public class AuthRepository
         string? userAgent)
     {
         using var db = Connection;
-        return await db.QuerySingleOrDefaultAsync<int?>(
+        var result = await db.QuerySingleOrDefaultAsync<string?>(
             "sp_RefreshToken_Replace",
             new
             {
-                p_old_token_id = oldTokenId,
-                p_id_user = userId,
+                p_old_token_id = oldTokenId.ToString(),
+                p_id_refresh_token = newTokenId.ToString(),
+                p_id_user = userId.ToString(),
                 p_token_hash = tokenHash,
                 p_token_salt = tokenSalt,
                 p_expires_in_seconds = expiresInSeconds,
@@ -73,5 +78,6 @@ public class AuthRepository
                 p_user_agent = userAgent
             },
             commandType: CommandType.StoredProcedure);
+        return result != null ? Guid.Parse(result) : null;
     }
 }
diff --git a/api/src/DataAccess/Repositories/StudentRepository.cs b/api/src/DataAccess/Repositories/StudentRepository.cs
index 9dbbebb..c646958 100644
--- a/api/src/DataAccess/Repositories/StudentRepository.cs
+++ b/api/src/DataAccess/Repositories/StudentRepository.cs
@@ -16,12 +16,12 @@ public class StudentRepository
             commandType: CommandType.StoredProcedure);
     }
 
-    public async Task<dbStudent?> GetByIdAsync(int idStudent)
+    public async Task<dbStudent?> GetByIdAsync(Guid idStudent)
     {
         using var db = Connection;
         return await db.QuerySingleOrDefaultAsync<dbStudent>(
             "sp_Student_GetById",
-            new { p_id_student = idStudent },
+            new { p_id_student = idStudent.ToString() },
             commandType: CommandType.StoredProcedure);
     }
 
@@ -32,8 +32,8 @@ public class StudentRepository
             "sp_Student_Insert",
             new
             {
-                p_id_student = dto.IdStudent,
-                p_id_program = dto.IdProgram,
+                p_id_student = dto.IdStudent.ToString(),
+                p_id_program = dto.IdProgram?.ToString(),
                 p_identifier = dto.Identifier,
                 p_program_year = dto.ProgramYear,
                 p_enrollment_date = dto.EnrollmentDate,
@@ -42,15 +42,15 @@ public class StudentRepository
             commandType: CommandType.StoredProcedure);
     }
 
-    public async Task<bool> UpdateAsync(int idStudent, UpdateStudentDto dto)
+    public async Task<bool> UpdateAsync(Guid idStudent, UpdateStudentDto dto)
     {
         using var db = Connection;
         var rowsAffected = await db.ExecuteScalarAsync<int>(
             "sp_Student_Update",
             new
             {
-                p_id_student = idStudent,
-                p_id_program = dto.IdProgram,
+                p_id_student = idStudent.ToString(),
+                p_id_program = dto.IdProgram?.ToString(),
                 p_identifier = dto.Identifier,
                 p_program_year = dto.ProgramYear,
                 p_enrollment_date = dto.EnrollmentDate,
@@ -60,12 +60,12 @@ public class StudentRepository
         return rowsAffected > 0;
     }
 
-    public async Task<bool> DeleteAsync(int idStudent)
+    public async Task<bool> DeleteAsync(Guid idStudent)
     {
         using var db = Connection;
         var rowsAffected = await db.ExecuteScalarAsync<int>(
             "sp_Student_Delete",
-            new { p_id_student = idStudent },
+            new { p_id_student = idStudent.ToString() },
             commandType: CommandType.StoredProcedure);
         return rowsAffected > 0;
     }
diff --git a/api/src/DataAccess/Repositories/UserRepository.cs b/api/src/DataAccess/Repositories/UserRepository.cs
index 97421ea..ff679a7 100644
--- a/api/src/DataAccess/Repositories/UserRepository.cs
+++ b/api/src/DataAccess/Repositories/UserRepository.cs
@@ -17,12 +17,12 @@ public class UserRepository
             commandType: CommandType.StoredProcedure);
     }
 
-    public async Task<dbUser?> GetByIdAsync(int idUser)
+    public async Task<dbUser?> GetByIdAsync(Guid idUser)
     {
         using var db = Connection;
         return await db.QuerySingleOrDefaultAsync<dbUser>(
             "sp_User_GetById",
-            new { p_id_user = idUser },
+            new { p_id_user = idUser.ToString() },
             commandType: CommandType.StoredProcedure);
     }
 }
diff --git a/api/src/Models/ResponseTypes/LoginResponse.cs b/api/src/Models/ResponseTypes/LoginResponse.cs
index dfdb325..da90350 100644
--- a/api/src/Models/ResponseTypes/LoginResponse.cs
+++ b/api/src/Models/ResponseTypes/LoginResponse.cs
@@ -2,7 +2,7 @@ namespace WinStudentGoalTracker.Models;
 
 public class LoginResponse
 {
-    public int UserId { get; set; }
+    public Guid UserId { get; set; }
     public required string Email { get; set; }
     public required string Jwt { get; set; }
     public required string RefreshToken { get; set; }
diff --git a/api/src/Models/ResponseTypes/StudentResponse.cs b/api/src/Models/ResponseTypes/StudentResponse.cs
index b0aed06..c538431 100644
--- a/api/src/Models/ResponseTypes/StudentResponse.cs
+++ b/api/src/Models/ResponseTypes/StudentResponse.cs
@@ -4,8 +4,8 @@ namespace WinStudentGoalTracker.Models;
 
 public class StudentResponse
 {
-    public int IdStudent { get; set; }
-    public int? IdProgram { get; set; }
+    public Guid IdStudent { get; set; }
+    public Guid? IdProgram { get; set; }
     public string? Identifier { get; set; }
     public int? ProgramYear { get; set; }
     public DateTime? EnrollmentDate { get; set; }
diff --git a/api/src/Services/TokenService.cs b/api/src/Services/TokenService.cs
index 2512ea1..9824a48 100644
--- a/api/src/Services/TokenService.cs
+++ b/api/src/Services/TokenService.cs
@@ -15,7 +15,7 @@ public class TokenService
         _config = config;
     }
 
-    public string GenerateToken(int userId, string email, string? roleName)
+    public string GenerateToken(Guid userId, string email, string? roleName)
     {
         var claims = new List<Claim>
         {