diff --git a/backend/internal/sink/assetscache/assets.go b/backend/internal/sink/assetscache/assets.go
index 96f225a45..aa2dccbba 100644
--- a/backend/internal/sink/assetscache/assets.go
+++ b/backend/internal/sink/assetscache/assets.go
@@ -12,6 +12,7 @@ import (
 	"openreplay/backend/pkg/monitoring"
 	"openreplay/backend/pkg/queue/types"
 	"openreplay/backend/pkg/url/assets"
+	"sync"
 	"time"
 )
 
@@ -21,6 +22,7 @@ type CachedAsset struct {
 }
 
 type AssetsCache struct {
+	mutex         sync.RWMutex
 	cfg           *sink.Config
 	rewriter      *assets.Rewriter
 	producer      types.Producer
@@ -54,7 +56,7 @@ func New(cfg *sink.Config, rewriter *assets.Rewriter, producer types.Producer, m
 	if err != nil {
 		log.Printf("can't create asset_duration metric: %s", err)
 	}
-	return &AssetsCache{
+	assetsCache := &AssetsCache{
 		cfg:           cfg,
 		rewriter:      rewriter,
 		producer:      producer,
@@ -65,6 +67,35 @@ func New(cfg *sink.Config, rewriter *assets.Rewriter, producer types.Producer, m
 		assetSize:     assetSize,
 		assetDuration: assetDuration,
 	}
+	go assetsCache.cleaner()
+	return assetsCache
+}
+
+func (e *AssetsCache) cleaner() {
+	cleanTick := time.Tick(time.Minute * 30)
+	for {
+		select {
+		case <-cleanTick:
+			e.clearCache()
+		}
+	}
+}
+
+func (e *AssetsCache) clearCache() {
+	e.mutex.Lock()
+	defer e.mutex.Unlock()
+
+	now := time.Now()
+	cacheSize := len(e.cache)
+	deleted := 0
+
+	for id, cache := range e.cache {
+		if int64(now.Sub(cache.ts).Minutes()) > e.cfg.CacheExpiration {
+			deleted++
+			delete(e.cache, id)
+		}
+	}
+	log.Printf("cache cleaner: deleted %d/%d assets", deleted, cacheSize)
 }
 
 func (e *AssetsCache) ParseAssets(msg messages.Message) messages.Message {
@@ -169,7 +200,10 @@ func (e *AssetsCache) handleCSS(sessionID uint64, baseURL string, css string) st
 	io.WriteString(h, css)
 	hash := string(h.Sum(nil))
 	// Check the resulting hash in cache
-	if cachedAsset, ok := e.cache[hash]; ok {
+	e.mutex.RLock()
+	cachedAsset, ok := e.cache[hash]
+	e.mutex.RUnlock()
+	if ok {
 		if int64(time.Now().Sub(cachedAsset.ts).Minutes()) < e.cfg.CacheExpiration {
 			e.skippedAssets.Add(ctx, 1)
 			return cachedAsset.msg
@@ -187,10 +221,12 @@ func (e *AssetsCache) handleCSS(sessionID uint64, baseURL string, css string) st
 	e.assetDuration.Record(ctx, float64(duration))
 	// Save asset to cache if we spent more than threshold
 	if duration > e.cfg.CacheThreshold {
+		e.mutex.Lock()
 		e.cache[hash] = &CachedAsset{
 			msg: res,
 			ts:  time.Now(),
 		}
+		e.mutex.Unlock()
 		e.cachedAssets.Add(ctx, 1)
 	}
 	// Return rewritten asset