diff --git a/kvstore/kvstore.go b/kvstore/kvstore.go
new file mode 100644
index 0000000..532ac5e
--- /dev/null
+++ b/kvstore/kvstore.go
@@ -0,0 +1,156 @@
+package kvstore
+
+import (
+	"encoding/json"
+	"os"
+	"sync"
+	"time"
+)
+
+type DataEntry struct {
+	Value     string    `json:"value"`
+	Timestamp time.Time `json:"timestamp"`
+}
+
+type KVStore struct {
+	data     sync.Map // klucz: string, wartość: DataEntry
+	filePath string
+	done     chan struct{}
+}
+
+func NewKVStore(filePath string) (*KVStore, error) {
+	store := &KVStore{
+		filePath: filePath,
+		done:     make(chan struct{}),
+	}
+
+	if _, err := os.Stat(filePath); !os.IsNotExist(err) {
+		if err := store.load(); err != nil {
+			return nil, err
+		}
+	}
+
+	go store.periodicSave()
+	return store, nil
+}
+
+// Set zapisuje wartość z automatycznym timestampem
+func (kv *KVStore) Set(key string, value string) {
+	entry := DataEntry{
+		Value:     value,
+		Timestamp: time.Now(),
+	}
+	kv.data.Store(key, entry)
+}
+
+// SetWithTimestamp pozwala na ustawienie własnego timestampa
+func (kv *KVStore) SetWithTimestamp(key string, value string, timestamp time.Time) {
+	entry := DataEntry{
+		Value:     value,
+		Timestamp: timestamp,
+	}
+	kv.data.Store(key, entry)
+}
+
+// Get zwraca DataEntry dla danego klucza
+func (kv *KVStore) Get(key string) (DataEntry, bool) {
+	if value, ok := kv.data.Load(key); ok {
+		return value.(DataEntry), true
+	}
+	return DataEntry{}, false
+}
+
+// GetValue zwraca tylko wartość (string) dla danego klucza
+func (kv *KVStore) GetValue(key string) (string, bool) {
+	if value, ok := kv.data.Load(key); ok {
+		return value.(DataEntry).Value, true
+	}
+	return "", false
+}
+
+func (kv *KVStore) Delete(key string) {
+	kv.data.Delete(key)
+}
+
+func (kv *KVStore) periodicSave() {
+	ticker := time.NewTicker(1 * time.Minute)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			kv.save()
+		case <-kv.done:
+			return
+		}
+	}
+}
+
+func (kv *KVStore) load() error {
+	file, err := os.ReadFile(kv.filePath)
+	if err != nil {
+		return err
+	}
+
+	var data map[string]DataEntry
+	if err := json.Unmarshal(file, &data); err != nil {
+		return err
+	}
+
+	for k, v := range data {
+		kv.data.Store(k, v)
+	}
+
+	return nil
+}
+
+func (kv *KVStore) save() error {
+	data := make(map[string]DataEntry)
+	kv.data.Range(func(key, value interface{}) bool {
+		if k, ok := key.(string); ok {
+			data[k] = value.(DataEntry)
+		}
+		return true
+	})
+
+	file, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(kv.filePath, file, 0644)
+}
+
+func (kv *KVStore) Close() error {
+	close(kv.done)
+	return kv.save()
+}
+
+// Dodatkowe pomocnicze metody
+
+// GetAll zwraca wszystkie wpisy
+func (kv *KVStore) GetAll() map[string]DataEntry {
+	result := make(map[string]DataEntry)
+	kv.data.Range(func(key, value interface{}) bool {
+		if k, ok := key.(string); ok {
+			result[k] = value.(DataEntry)
+		}
+		return true
+	})
+	return result
+}
+
+// GetEntriesAfter zwraca wpisy po określonej dacie
+func (kv *KVStore) GetEntriesAfter(timestamp time.Time) map[string]DataEntry {
+	result := make(map[string]DataEntry)
+	kv.data.Range(func(key, value interface{}) bool {
+		if k, ok := key.(string); ok {
+			entry := value.(DataEntry)
+			if entry.Timestamp.After(timestamp) {
+				result[k] = entry
+			}
+		}
+		return true
+	})
+	return result
+}
diff --git a/kvstore/kvstore_bench_test.go b/kvstore/kvstore_bench_test.go
new file mode 100644
index 0000000..3ca5299
--- /dev/null
+++ b/kvstore/kvstore_bench_test.go
@@ -0,0 +1,117 @@
+package kvstore
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"sync"
+	"testing"
+)
+
+func BenchmarkKVStore_Set_Parallel(b *testing.B) {
+	store, err := NewKVStore("benchmark_test.db")
+	if err != nil {
+		b.Fatalf("Failed to create KVStore: %v", err)
+	}
+	defer os.Remove("benchmark_test.db")
+	defer store.Close()
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		counter := 0
+		for pb.Next() {
+			store.Set(fmt.Sprintf("key-%d", counter), strconv.Itoa(counter))
+			counter++
+		}
+	})
+}
+
+func BenchmarkKVStore_Get_Parallel(b *testing.B) {
+	store, err := NewKVStore("benchmark_test.db")
+	if err != nil {
+		b.Fatalf("Failed to create KVStore: %v", err)
+	}
+	defer os.Remove("benchmark_test.db")
+	defer store.Close()
+
+	// Przygotowanie danych
+	for i := 0; i < 1000; i++ {
+		store.Set(fmt.Sprintf("key-%d", i), strconv.Itoa(i))
+	}
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		counter := 0
+		for pb.Next() {
+			store.Get(fmt.Sprintf("key-%d", counter%1000))
+			counter++
+		}
+	})
+}
+
+func BenchmarkKVStore_Mixed_Parallel(b *testing.B) {
+	store, err := NewKVStore("benchmark_test.db")
+	if err != nil {
+		b.Fatalf("Failed to create KVStore: %v", err)
+	}
+	defer os.Remove("benchmark_test.db")
+	defer store.Close()
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		counter := 0
+		for pb.Next() {
+			key := "key-" + strconv.Itoa(counter)
+			switch counter % 3 {
+			case 0:
+				store.Set(key, strconv.Itoa(counter))
+			case 1:
+				store.Get(key)
+			case 2:
+				store.Delete(key)
+			}
+			counter++
+		}
+	})
+}
+
+func BenchmarkKVStore_Concurrent_HeavyLoad(b *testing.B) {
+	store, err := NewKVStore("benchmark_test.db")
+	if err != nil {
+		b.Fatalf("Failed to create KVStore: %v", err)
+	}
+	defer os.Remove("benchmark_test.db")
+	defer store.Close()
+
+	var wg sync.WaitGroup
+	workers := 100
+	opsPerWorker := b.N / workers
+
+	b.ResetTimer()
+
+	// Writers
+	for i := 0; i < workers/2; i++ {
+		wg.Add(1)
+		go func(workerID int) {
+			defer wg.Done()
+			for j := 0; j < opsPerWorker; j++ {
+				key := fmt.Sprintf("key-%d-%d", workerID, j)
+				store.Set(key, strconv.Itoa(j))
+			}
+		}(i)
+	}
+
+	// Readers
+	for i := workers / 2; i < workers; i++ {
+		wg.Add(1)
+		go func(workerID int) {
+			defer wg.Done()
+			for j := 0; j < opsPerWorker; j++ {
+				key := fmt.Sprintf("key-%d-%d", workerID%50, j)
+				store.Get(key)
+			}
+		}(i)
+	}
+
+	wg.Wait()
+}
diff --git a/main.go b/main.go
index c674cb9..2ff596c 100644
--- a/main.go
+++ b/main.go
@@ -5,24 +5,30 @@ package main
 import (
 	"encoding/json"
 	"fmt"
+	"log"
+	"mkedziora/fast-links/kvstore"
 	"net/http"
 	"strconv"
-	"sync"
 	"time"
 )
 
-type DataEntry struct {
-	Value     string
-	Timestamp time.Time
-}
+// var (
+// 	dataMap map[string]DataEntry
+// 	mu      sync.Mutex
+// )
 
-var (
-	dataMap map[string]DataEntry
-	mu      sync.Mutex
-)
+// func init() {
+// 	dataMap = make(map[string]DataEntry)
+// }
+
+var store *kvstore.KVStore
 
 func init() {
-	dataMap = make(map[string]DataEntry)
+	var err error
+	store, err = kvstore.NewKVStore("data.db")
+	if err != nil {
+		log.Fatalf("Failed to create KVStore: %v", err)
+	}
 }
 
 func setHandler(w http.ResponseWriter, r *http.Request) {
@@ -42,7 +48,7 @@ func setHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	mu.Lock()
+	// mu.Lock()
 	if input.ID == "" {
 		input.ID = "default"
 	}
@@ -64,11 +70,12 @@ func setHandler(w http.ResponseWriter, r *http.Request) {
 
 	expirationTime := time.Now().Add(time.Duration(expireSeconds) * time.Second)
 
-	dataMap[input.ID] = DataEntry{
-		Value:     input.Data,
-		Timestamp: expirationTime,
-	}
-	mu.Unlock()
+	store.SetWithTimestamp("key_"+input.ID, input.Data, expirationTime)
+	// dataMap[input.ID] = DataEntry{
+	// 	Value:     input.Data,
+	// 	Timestamp: expirationTime,
+	// }
+	// mu.Unlock()
 
 	w.WriteHeader(http.StatusNoContent)
 }
@@ -79,12 +86,14 @@ func getHandler(w http.ResponseWriter, r *http.Request) {
 		id = "default"
 	}
 
-	mu.Lock()
-	entry, exists := dataMap[id]
-	mu.Unlock()
+	// mu.Lock()
+	// entry, exists := dataMap[id]
+	// mu.Unlock()
+
+	entry, exists := store.Get("key_" + id)
 
 	if !exists || time.Since(entry.Timestamp) > 30*time.Second {
-		delete(dataMap, id)
+		store.Delete("key_" + id)
 		http.Error(w, "No data available", http.StatusNotFound)
 		return
 	}
@@ -99,12 +108,9 @@ func getUrlHandler(w http.ResponseWriter, r *http.Request) {
 		id = "default"
 	}
 
-	mu.Lock()
-	entry, exists := dataMap[id]
-	mu.Unlock()
-
+	entry, exists := store.Get("key_" + id)
 	if !exists || time.Since(entry.Timestamp) > 30*time.Second {
-		delete(dataMap, id)
+		store.Delete("key_" + id)
 		http.Error(w, "No data available", http.StatusNotFound)
 		return
 	}
@@ -114,6 +120,7 @@ func getUrlHandler(w http.ResponseWriter, r *http.Request) {
 }
 
 func main() {
+
 	// Obsługa endpointów API
 	http.HandleFunc("/api/set", setHandler)
 	http.HandleFunc("/api/get", getHandler)
@@ -150,9 +157,10 @@ func main() {
 
 	go func() {
 		for {
-			for id, timestamp := range dataMap {
+
+			for id, timestamp := range store.GetAll() {
 				if time.Now().After(timestamp.Timestamp) {
-					delete(dataMap, id)
+					store.Delete(id)
 					break
 				}
 			}