diff --git a/database/schema/schema.sql b/database/schema/schema.sql
index 033d981..0743e4a 100644
--- a/database/schema/schema.sql
+++ b/database/schema/schema.sql
@@ -32,6 +32,16 @@ CREATE TABLE users (
     updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
 );
 
+-- Create refresh_tokens table
+CREATE TABLE refresh_tokens (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    token VARCHAR(255) UNIQUE NOT NULL,
+    expires_at TIMESTAMP WITH TIME ZONE NOT NULL,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    revoked_at TIMESTAMP WITH TIME ZONE
+);
+
 -- Create libraries table
 CREATE TABLE libraries (
     id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
@@ -189,6 +199,8 @@ WHERE lt.name = 'ebooks';
 CREATE INDEX idx_users_email ON users(email);
 CREATE INDEX idx_users_username ON users(username);
 CREATE INDEX idx_library_types_name ON library_types(name);
+CREATE INDEX idx_refresh_tokens_token ON refresh_tokens(token);
+CREATE INDEX idx_refresh_tokens_user_id ON refresh_tokens(user_id);
 
 -- Library indexes
 CREATE INDEX idx_libraries_name ON libraries(name);
diff --git a/internal/database/queries/queries.sql b/internal/database/queries/queries.sql
index 45f2744..1c334c4 100644
--- a/internal/database/queries/queries.sql
+++ b/internal/database/queries/queries.sql
@@ -377,4 +377,25 @@ WHERE id = $1
 RETURNING *;
 
 -- name: DeleteEbookHighlight :exec
-DELETE FROM media_highlights WHERE id = $1;
\ No newline at end of file
+DELETE FROM media_highlights WHERE id = $1;
+
+-- Refresh Tokens queries
+-- name: CreateRefreshToken :one
+INSERT INTO refresh_tokens (user_id, token, expires_at)
+VALUES ($1, $2, $3)
+RETURNING *;
+
+-- name: GetRefreshToken :one
+SELECT rt.*, u.email, u.username, u.role
+FROM refresh_tokens rt
+JOIN users u ON rt.user_id = u.id
+WHERE rt.token = $1 AND rt.revoked_at IS NULL AND rt.expires_at > NOW();
+
+-- name: RevokeRefreshToken :exec
+UPDATE refresh_tokens SET revoked_at = NOW() WHERE token = $1;
+
+-- name: RevokeAllUserRefreshTokens :exec
+UPDATE refresh_tokens SET revoked_at = NOW() WHERE user_id = $1 AND revoked_at IS NULL;
+
+-- name: CleanupExpiredRefreshTokens :exec
+DELETE FROM refresh_tokens WHERE expires_at < NOW() OR (revoked_at IS NOT NULL AND revoked_at < NOW() - INTERVAL '7 days');
\ No newline at end of file
diff --git a/internal/middleware/login_attempts.go b/internal/middleware/login_attempts.go
new file mode 100644
index 0000000..a562bd2
--- /dev/null
+++ b/internal/middleware/login_attempts.go
@@ -0,0 +1,121 @@
+package middleware
+
+import (
+	"sync"
+	"time"
+)
+
+// LoginAttemptTracker tracks failed login attempts per IP and username
+type LoginAttemptTracker struct {
+	mu              sync.RWMutex
+	attempts        map[string]*AttemptInfo
+	maxAttempts     int
+	lockoutDuration time.Duration
+	cleanupInterval time.Duration
+}
+
+// AttemptInfo stores information about login attempts
+type AttemptInfo struct {
+	AttemptCount int
+	LockedUntil  time.Time
+	LastAttempt  time.Time
+}
+
+// NewLoginAttemptTracker creates a new login attempt tracker
+func NewLoginAttemptTracker(maxAttempts int, lockoutDuration, cleanupInterval time.Duration) *LoginAttemptTracker {
+	tracker := &LoginAttemptTracker{
+		attempts:        make(map[string]*AttemptInfo),
+		maxAttempts:     maxAttempts,
+		lockoutDuration: lockoutDuration,
+		cleanupInterval: cleanupInterval,
+	}
+
+	// Start cleanup goroutine
+	go tracker.cleanup()
+
+	return tracker
+}
+
+// RecordFailedAttempt records a failed login attempt
+func (t *LoginAttemptTracker) RecordFailedAttempt(identifier string) (locked bool, remainingTime time.Duration) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	now := time.Now()
+	info, exists := t.attempts[identifier]
+
+	if !exists {
+		info = &AttemptInfo{
+			AttemptCount: 1,
+			LastAttempt:  now,
+		}
+		t.attempts[identifier] = info
+		return false, 0
+	}
+
+	// Check if currently locked
+	if now.Before(info.LockedUntil) {
+		return true, time.Until(info.LockedUntil)
+	}
+
+	// Reset attempts if last attempt was more than lockoutDuration ago
+	if now.Sub(info.LastAttempt) > t.lockoutDuration {
+		info.AttemptCount = 1
+	} else {
+		info.AttemptCount++
+	}
+
+	info.LastAttempt = now
+
+	// Check if max attempts reached
+	if info.AttemptCount >= t.maxAttempts {
+		info.LockedUntil = now.Add(t.lockoutDuration)
+		return true, t.lockoutDuration
+	}
+
+	return false, 0
+}
+
+// IsLocked checks if an identifier is currently locked out
+func (t *LoginAttemptTracker) IsLocked(identifier string) (locked bool, remainingTime time.Duration) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	info, exists := t.attempts[identifier]
+	if !exists {
+		return false, 0
+	}
+
+	now := time.Now()
+	if now.Before(info.LockedUntil) {
+		return true, time.Until(info.LockedUntil)
+	}
+
+	return false, 0
+}
+
+// ClearAttempts clears failed login attempts for an identifier
+func (t *LoginAttemptTracker) ClearAttempts(identifier string) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	delete(t.attempts, identifier)
+}
+
+// cleanup removes old attempt records periodically
+func (t *LoginAttemptTracker) cleanup() {
+	ticker := time.NewTicker(t.cleanupInterval)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		t.mu.Lock()
+		now := time.Now()
+		for identifier, info := range t.attempts {
+			// Remove records that are not locked and haven't had recent attempts
+			if now.After(info.LockedUntil) && now.Sub(info.LastAttempt) > t.lockoutDuration*2 {
+				delete(t.attempts, identifier)
+			}
+		}
+		t.mu.Unlock()
+	}
+}
diff --git a/internal/middleware/password_validator.go b/internal/middleware/password_validator.go
new file mode 100644
index 0000000..159c3aa
--- /dev/null
+++ b/internal/middleware/password_validator.go
@@ -0,0 +1,96 @@
+package middleware
+
+import (
+	"fmt"
+	"regexp"
+
+	"github.com/go-playground/validator/v10"
+)
+
+// PasswordValidator validates password complexity requirements
+type PasswordValidator struct{}
+
+// Validate checks if a password meets complexity requirements:
+// - Minimum 8 characters
+// - At least one uppercase letter
+// - At least one lowercase letter
+// - At least one number
+// - At least one special character
+func (v *PasswordValidator) Validate(fl validator.FieldLevel) bool {
+	password := fl.Field().String()
+
+	// Check minimum length
+	if len(password) < 8 {
+		return false
+	}
+
+	// Check for uppercase
+	hasUpper := regexp.MustCompile(`[A-Z]`).MatchString(password)
+	if !hasUpper {
+		return false
+	}
+
+	// Check for lowercase
+	hasLower := regexp.MustCompile(`[a-z]`).MatchString(password)
+	if !hasLower {
+		return false
+	}
+
+	// Check for number
+	hasNumber := regexp.MustCompile(`[0-9]`).MatchString(password)
+	if !hasNumber {
+		return false
+	}
+
+	// Check for special character
+	hasSpecial := regexp.MustCompile(`[!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?]`).MatchString(password)
+	if !hasSpecial {
+		return false
+	}
+
+	return true
+}
+
+// GetPasswordRequirements returns a human-readable list of password requirements
+func GetPasswordRequirements() []string {
+	return []string{
+		"At least 8 characters long",
+		"At least one uppercase letter (A-Z)",
+		"At least one lowercase letter (a-z)",
+		"At least one number (0-9)",
+		"At least one special character (!@#$%^&*()_+-=[]{}|;':\",./<>?)",
+	}
+}
+
+// ValidatePassword checks a password and returns an error if it doesn't meet requirements
+func ValidatePassword(password string) error {
+	if len(password) < 8 {
+		return fmt.Errorf("password must be at least 8 characters long")
+	}
+
+	if !regexp.MustCompile(`[A-Z]`).MatchString(password) {
+		return fmt.Errorf("password must contain at least one uppercase letter")
+	}
+
+	if !regexp.MustCompile(`[a-z]`).MatchString(password) {
+		return fmt.Errorf("password must contain at least one lowercase letter")
+	}
+
+	if !regexp.MustCompile(`[0-9]`).MatchString(password) {
+		return fmt.Errorf("password must contain at least one number")
+	}
+
+	if !regexp.MustCompile(`[!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?]`).MatchString(password) {
+		return fmt.Errorf("password must contain at least one special character")
+	}
+
+	return nil
+}
+
+// RegisterPasswordValidation registers the password validator with the validator instance
+func RegisterPasswordValidation(v *validator.Validate) error {
+	return v.RegisterValidation("passwordcomplex", func(fl validator.FieldLevel) bool {
+		pv := &PasswordValidator{}
+		return pv.Validate(fl)
+	})
+}