diff --git a/src/FiscalOS.Infra/Data/AppDbContext.cs b/src/FiscalOS.Infra/Data/AppDbContext.cs
index db90d6f..c57edf8 100644
--- a/src/FiscalOS.Infra/Data/AppDbContext.cs
+++ b/src/FiscalOS.Infra/Data/AppDbContext.cs
@@ -45,18 +45,24 @@ public sealed class AppDbContext(IOptions<AppDbContextOptions> ctxOptions) : DbC
 
     modelBuilder.Entity<User>(static eb =>
     {
+
       eb.HasMany(static u => u.RefreshTokens)
         .WithOne(static t => t.User)
         .HasForeignKey(static t => t.UserId)
         .OnDelete(DeleteBehavior.Cascade);
 
       eb.Property(static u => u.Username);
-      eb.Property(static u => u.HashedPassword); });
+      eb.HasIndex(static u => u.Username).IsUnique();
+
+      eb.Property(static u => u.HashedPassword);
+    });
     modelBuilder.Entity<RefreshToken>(static eb =>
     {
       eb.Property(static t => t.Id);
       eb.Property(static t => t.ExpiresAt);
+
       eb.Property(static t => t.Token);
+      eb.HasIndex(static t => t.Token).IsUnique();
     });
   }
 }
\ No newline at end of file
diff --git a/src/FiscalOS.Infra/Migrations/20260202214513_AddIndexesWithUniquenessToModels.Designer.cs b/src/FiscalOS.Infra/Migrations/20260202214513_AddIndexesWithUniquenessToModels.Designer.cs
new file mode 100644
index 0000000..9a16ce5
--- /dev/null
+++ b/src/FiscalOS.Infra/Migrations/20260202214513_AddIndexesWithUniquenessToModels.Designer.cs
@@ -0,0 +1,101 @@
+// <auto-generated />
+using System;
+using FiscalOS.Infra.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace FiscalOS.Infra.Migrations
+{
+    [DbContext(typeof(AppDbContext))]
+    [Migration("20260202214513_AddIndexesWithUniquenessToModels")]
+    partial class AddIndexesWithUniquenessToModels
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "10.0.2");
+
+            modelBuilder.Entity("FiscalOS.Core.Identity.RefreshToken", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTimeOffset>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTimeOffset>("ExpiresAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Token")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTimeOffset>("UpdatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Token")
+                        .IsUnique();
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("RefreshTokens");
+                });
+
+            modelBuilder.Entity("FiscalOS.Core.Identity.User", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTimeOffset>("CreatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("HashedPassword")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTimeOffset>("UpdatedAt")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Username")
+                        .IsUnique();
+
+                    b.ToTable("Users");
+                });
+
+            modelBuilder.Entity("FiscalOS.Core.Identity.RefreshToken", b =>
+                {
+                    b.HasOne("FiscalOS.Core.Identity.User", "User")
+                        .WithMany("RefreshTokens")
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("FiscalOS.Core.Identity.User", b =>
+                {
+                    b.Navigation("RefreshTokens");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/src/FiscalOS.Infra/Migrations/20260202214513_AddIndexesWithUniquenessToModels.cs b/src/FiscalOS.Infra/Migrations/20260202214513_AddIndexesWithUniquenessToModels.cs
new file mode 100644
index 0000000..7206d67
--- /dev/null
+++ b/src/FiscalOS.Infra/Migrations/20260202214513_AddIndexesWithUniquenessToModels.cs
@@ -0,0 +1,38 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace FiscalOS.Infra.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddIndexesWithUniquenessToModels : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateIndex(
+                name: "IX_Users_Username",
+                table: "Users",
+                column: "Username",
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_RefreshTokens_Token",
+                table: "RefreshTokens",
+                column: "Token",
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Users_Username",
+                table: "Users");
+
+            migrationBuilder.DropIndex(
+                name: "IX_RefreshTokens_Token",
+                table: "RefreshTokens");
+        }
+    }
+}
diff --git a/src/FiscalOS.Infra/Migrations/AppDbContextModelSnapshot.cs b/src/FiscalOS.Infra/Migrations/AppDbContextModelSnapshot.cs
index 0a74549..9228af1 100644
--- a/src/FiscalOS.Infra/Migrations/AppDbContextModelSnapshot.cs
+++ b/src/FiscalOS.Infra/Migrations/AppDbContextModelSnapshot.cs
@@ -41,6 +41,9 @@ namespace FiscalOS.Infra.Migrations
 
                     b.HasKey("Id");
 
+                    b.HasIndex("Token")
+                        .IsUnique();
+
                     b.HasIndex("UserId");
 
                     b.ToTable("RefreshTokens");
@@ -68,6 +71,9 @@ namespace FiscalOS.Infra.Migrations
 
                     b.HasKey("Id");
 
+                    b.HasIndex("Username")
+                        .IsUnique();
+
                     b.ToTable("Users");
                 });