diff --git a/rewrites.go b/rewrites.go
new file mode 100644
index 0000000..bd74731
--- /dev/null
+++ b/rewrites.go
@@ -0,0 +1,86 @@
+package main
+
+import (
+	"fmt"
+)
+
+type Rewrite struct {
+	Domain string `yaml:"domain" json:"domain"`
+	Answer string `yaml:"answer" json:"answer"`
+}
+
+func MergeRewrites(existing, desired []Rewrite) []Rewrite {
+	existingMap := make(map[string]string)
+	for _, r := range existing {
+		existingMap[r.Domain] = r.Answer
+	}
+
+	desiredMap := make(map[string]string)
+	for _, r := range desired {
+		desiredMap[r.Domain] = r.Answer
+	}
+
+	updated := make([]Rewrite, 0)
+
+	// Add or update
+	for domain, ip := range desiredMap {
+		if existingIP, found := existingMap[domain]; found {
+			if existingIP != ip {
+				fmt.Printf("Ändere %s: %s -> %s\n", domain, existingIP, ip)
+			}
+		} else {
+			fmt.Printf("Füge hinzu: %s -> %s\n", domain, ip)
+		}
+		updated = append(updated, Rewrite{Domain: domain, Answer: ip})
+	}
+
+	// Delete outdated
+	for domain, ip := range existingMap {
+		if _, ok := desiredMap[domain]; !ok {
+			fmt.Printf("Lösche: %s : %s\n", domain, ip)
+		}
+	}
+
+	return updated
+}
+
+func (c *AdGuardClient) ApplyRewrites(desired []Rewrite) error {
+	existing, err := c.GetRewrites()
+	if err != nil {
+		return err
+	}
+
+	existingMap := make(map[string]string)
+	for _, r := range existing {
+		existingMap[r.Domain] = r.Answer
+	}
+
+	desiredMap := make(map[string]string)
+	for _, r := range desired {
+		desiredMap[r.Domain] = r.Answer
+	}
+
+	for domain, ip := range desiredMap {
+		if existingIP, ok := existingMap[domain]; ok {
+			if existingIP != ip {
+				if err := c.UpdateRewrite(Rewrite{Domain: domain, Answer: existingIP}, Rewrite{Domain: domain, Answer: ip}); err != nil {
+					return err
+				}
+			}
+		} else {
+			if err := c.AddRewrite(Rewrite{Domain: domain, Answer: ip}); err != nil {
+				return err
+			}
+		}
+	}
+
+	for domain, ip := range existingMap {
+		if _, ok := desiredMap[domain]; !ok {
+			if err := c.DeleteRewrite(Rewrite{Domain: domain, Answer: ip}); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}