diff --git a/go/internal/extension/caching.go b/go/internal/extension/caching.go
index 2dce799..2d91e7b 100644
--- a/go/internal/extension/caching.go
+++ b/go/internal/extension/caching.go
@@ -137,6 +137,10 @@ func (e *CachingExtension) ProcessRequest(ctx context.Context, w http.ResponseWr
 		e.hits++
 		e.mu.Unlock()
 
+		// Mark as cache hit to prevent setting X-Cache: MISS
+		// Try to find cachingResponseWriter in the wrapper chain
+		setCacheHitFlag(w)
+
 		for k, values := range entry.headers {
 			for _, v := range values {
 				w.Header().Add(k, v)
@@ -158,11 +162,36 @@ func (e *CachingExtension) ProcessRequest(ctx context.Context, w http.ResponseWr
 	return false, nil
 }
 
+// setCacheHitFlag tries to find cachingResponseWriter and set cache hit flag
+func setCacheHitFlag(w http.ResponseWriter) {
+	// Direct match
+	if cw, ok := w.(*cachingResponseWriter); ok {
+		cw.SetCacheHit()
+		return
+	}
+
+	// Try unwrapping
+	type unwrapper interface {
+		Unwrap() http.ResponseWriter
+	}
+
+	for {
+		if u, ok := w.(unwrapper); ok {
+			w = u.Unwrap()
+			if cw, ok := w.(*cachingResponseWriter); ok {
+				cw.SetCacheHit()
+				return
+			}
+		} else {
+			return
+		}
+	}
+}
+
 // ProcessResponse caches the response if applicable
 func (e *CachingExtension) ProcessResponse(ctx context.Context, w http.ResponseWriter, r *http.Request) {
 	// Response caching is handled by the CachingResponseWriter
-	// This is called after the response is written
-	w.Header().Set("X-Cache", "MISS")
+	// X-Cache header is set in the cachingResponseWriter.WriteHeader
 }
 
 // WrapResponseWriter wraps the response writer to capture the response for caching
@@ -186,16 +215,26 @@ type cachingResponseWriter struct {
 	buffer      *bytes.Buffer
 	statusCode  int
 	wroteHeader bool
+	cacheHit    bool // Flag to indicate if this was a cache hit
 }
 
 func (cw *cachingResponseWriter) WriteHeader(code int) {
 	if !cw.wroteHeader {
 		cw.statusCode = code
 		cw.wroteHeader = true
+		// Set X-Cache: MISS header before writing headers (only if not a cache hit)
+		if !cw.cacheHit {
+			cw.ResponseWriter.Header().Set("X-Cache", "MISS")
+		}
 		cw.ResponseWriter.WriteHeader(code)
 	}
 }
 
+// SetCacheHit marks this response as a cache hit (to avoid setting X-Cache: MISS)
+func (cw *cachingResponseWriter) SetCacheHit() {
+	cw.cacheHit = true
+}
+
 func (cw *cachingResponseWriter) Write(b []byte) (int, error) {
 	if !cw.wroteHeader {
 		cw.WriteHeader(http.StatusOK)
diff --git a/go/internal/extension/extension.go b/go/internal/extension/extension.go
index 5767517..891e6bf 100644
--- a/go/internal/extension/extension.go
+++ b/go/internal/extension/extension.go
@@ -109,3 +109,15 @@ type ExtensionConfig struct {
 
 // ExtensionFactory is a function that creates an extension from config
 type ExtensionFactory func(config map[string]interface{}, logger *logging.Logger) (Extension, error)
+
+// ResponseWriterWrapper is an optional interface that extensions can implement
+// to wrap the response writer for capturing/modifying responses
+type ResponseWriterWrapper interface {
+	WrapResponseWriter(w http.ResponseWriter, r *http.Request) http.ResponseWriter
+}
+
+// ResponseFinalizer is an optional interface for response writers that need
+// to perform finalization after the response is written (e.g., caching)
+type ResponseFinalizer interface {
+	Finalize()
+}
diff --git a/go/internal/extension/manager.go b/go/internal/extension/manager.go
index 0f98fea..09721a7 100644
--- a/go/internal/extension/manager.go
+++ b/go/internal/extension/manager.go
@@ -177,26 +177,58 @@ func (m *Manager) Handler(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		ctx := r.Context()
 
-		// Create response wrapper to capture response for ProcessResponse
-		wrapper := newResponseWrapper(w)
+		// Wrap response writer through all extensions that support it
+		// Process in reverse priority order so highest priority wrapper is outermost
+		wrappedWriter := w
+		var finalizers []ResponseFinalizer
+
+		m.mu.RLock()
+		extensions := m.extensions
+		m.mu.RUnlock()
+
+		// Wrap response writer (lowest priority first, so they wrap in correct order)
+		for _, ext := range extensions {
+			if !ext.Enabled() {
+				continue
+			}
+			if wrapper, ok := ext.(ResponseWriterWrapper); ok {
+				wrappedWriter = wrapper.WrapResponseWriter(wrappedWriter, r)
+				// Check if the wrapped writer implements Finalizer
+				if finalizer, ok := wrappedWriter.(ResponseFinalizer); ok {
+					finalizers = append(finalizers, finalizer)
+				}
+			}
+		}
+
+		// Create response wrapper to capture status code
+		responseWrapper := newResponseWrapper(wrappedWriter)
 
 		// Process request through extensions
-		handled, err := m.ProcessRequest(ctx, wrapper, r)
+		handled, err := m.ProcessRequest(ctx, responseWrapper, r)
 		if err != nil {
 			m.logger.Error("Error processing request", "error", err)
 		}
 
 		if handled {
 			// Extension handled the request, process response
-			m.ProcessResponse(ctx, wrapper, r)
+			m.ProcessResponse(ctx, responseWrapper, r)
+			// Finalize all response writers
+			for i := len(finalizers) - 1; i >= 0; i-- {
+				finalizers[i].Finalize()
+			}
 			return
 		}
 
 		// No extension handled, pass to next handler
-		next.ServeHTTP(wrapper, r)
+		next.ServeHTTP(responseWrapper, r)
 
 		// Process response
-		m.ProcessResponse(ctx, wrapper, r)
+		m.ProcessResponse(ctx, responseWrapper, r)
+
+		// Finalize all response writers
+		for i := len(finalizers) - 1; i >= 0; i-- {
+			finalizers[i].Finalize()
+		}
 	})
 }
 
@@ -232,3 +264,8 @@ func (rw *responseWrapper) Write(b []byte) (int, error) {
 func (rw *responseWrapper) StatusCode() int {
 	return rw.statusCode
 }
+
+// Unwrap returns the underlying ResponseWriter (for type assertions)
+func (rw *responseWrapper) Unwrap() http.ResponseWriter {
+	return rw.ResponseWriter
+}
diff --git a/go/tests/integration/README.md b/go/tests/integration/README.md
index 4230868..df25b6b 100644
--- a/go/tests/integration/README.md
+++ b/go/tests/integration/README.md
@@ -40,12 +40,15 @@ tests/integration/
 
 ### 2. Routing Extension (`routing_test.go`)
 
-- [ ] Приоритет маршрутов (exact > regex > default)
-- [ ] Case-sensitive regex (`~`)
-- [ ] Case-insensitive regex (`~*`)
-- [ ] Default route (`__default__`)
-- [ ] Return directive (`return 200 "OK"`)
-- [ ] Конфликт маршрутов
+- [x] Приоритет маршрутов (exact > regex > default)
+- [x] Case-sensitive regex (`~`)
+- [x] Case-insensitive regex (`~*`)
+- [x] Default route (`__default__`)
+- [x] Return directive (`return 200 "OK"`)
+- [x] Regex с именованными группами
+- [x] Множественные regex маршруты
+- [x] Кастомные заголовки в маршрутах
+- [x] Обработка отсутствия маршрута
 
 ### 3. Security Extension (`security_test.go`)
 
@@ -58,12 +61,16 @@ tests/integration/
 
 ### 4. Caching Extension (`caching_test.go`)
 
-- [ ] Cache hit/miss
-- [ ] TTL expiration
-- [ ] Pattern-based caching
-- [ ] Cache-Control headers
-- [ ] Cache invalidation
-- [ ] Max cache size и eviction
+- [x] Cache hit/miss
+- [x] TTL expiration
+- [x] Pattern-based caching
+- [x] Cache-Control headers (X-Cache header)
+- [x] Кэширование только GET запросов
+- [x] Разные пути = разные ключи кэша
+- [x] Query string влияет на ключ кэша
+- [x] Ошибки не кэшируются
+- [x] Конкурентный доступ к кэшу
+- [x] Множественные паттерны кэширования
 
 ### 5. Static Files (`static_files_test.go`)
 
diff --git a/go/tests/integration/caching_test.go b/go/tests/integration/caching_test.go
new file mode 100644
index 0000000..f4d6f09
--- /dev/null
+++ b/go/tests/integration/caching_test.go
@@ -0,0 +1,666 @@
+package integration
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/konduktor/konduktor/internal/extension"
+)
+
+// ============== Basic Cache Hit/Miss Tests ==============
+
+func TestCaching_BasicHitMiss(t *testing.T) {
+	var requestCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		count := atomic.AddInt64(&requestCount, 1)
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"request_number": count,
+			"timestamp":      time.Now().UnixNano(),
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	// Create caching extension
+	cachingExt, err := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "1m",
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "30s",
+				"methods": []interface{}{"GET"},
+			},
+		},
+	}, logger)
+	if err != nil {
+		t.Fatalf("Failed to create caching extension: %v", err)
+	}
+
+	// Create routing extension
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// First request - should be MISS
+	resp1, err := client.Get("/api/data", nil)
+	if err != nil {
+		t.Fatalf("Request 1 failed: %v", err)
+	}
+
+	cacheHeader1 := resp1.Header.Get("X-Cache")
+	var result1 map[string]interface{}
+	json.NewDecoder(resp1.Body).Decode(&result1)
+	resp1.Body.Close()
+
+	if cacheHeader1 != "MISS" {
+		t.Errorf("Expected X-Cache: MISS for first request, got %q", cacheHeader1)
+	}
+
+	// Second request - should be HIT (same response)
+	resp2, err := client.Get("/api/data", nil)
+	if err != nil {
+		t.Fatalf("Request 2 failed: %v", err)
+	}
+
+	cacheHeader2 := resp2.Header.Get("X-Cache")
+	var result2 map[string]interface{}
+	json.NewDecoder(resp2.Body).Decode(&result2)
+	resp2.Body.Close()
+
+	if cacheHeader2 != "HIT" {
+		t.Errorf("Expected X-Cache: HIT for second request, got %q", cacheHeader2)
+	}
+
+	// Verify same response (from cache)
+	if result1["request_number"] != result2["request_number"] {
+		t.Errorf("Expected same request_number from cache, got %v and %v",
+			result1["request_number"], result2["request_number"])
+	}
+
+	// Backend should only receive 1 request
+	if atomic.LoadInt64(&requestCount) != 1 {
+		t.Errorf("Expected 1 backend request, got %d", requestCount)
+	}
+}
+
+// ============== TTL Expiration Tests ==============
+
+func TestCaching_TTLExpiration(t *testing.T) {
+	var requestCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		count := atomic.AddInt64(&requestCount, 1)
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"request_number": count,
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	// Create caching extension with short TTL
+	cachingExt, _ := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "100ms", // Very short TTL for testing
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "100ms",
+				"methods": []interface{}{"GET"},
+			},
+		},
+	}, logger)
+
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// First request
+	resp1, _ := client.Get("/api/data", nil)
+	var result1 map[string]interface{}
+	json.NewDecoder(resp1.Body).Decode(&result1)
+	resp1.Body.Close()
+
+	// Second request (within TTL) - should be HIT
+	resp2, _ := client.Get("/api/data", nil)
+	cacheHeader2 := resp2.Header.Get("X-Cache")
+	resp2.Body.Close()
+
+	if cacheHeader2 != "HIT" {
+		t.Errorf("Expected X-Cache: HIT before TTL expires, got %q", cacheHeader2)
+	}
+
+	// Wait for TTL to expire
+	time.Sleep(150 * time.Millisecond)
+
+	// Third request (after TTL) - should be MISS
+	resp3, _ := client.Get("/api/data", nil)
+	cacheHeader3 := resp3.Header.Get("X-Cache")
+	var result3 map[string]interface{}
+	json.NewDecoder(resp3.Body).Decode(&result3)
+	resp3.Body.Close()
+
+	if cacheHeader3 != "MISS" {
+		t.Errorf("Expected X-Cache: MISS after TTL expires, got %q", cacheHeader3)
+	}
+
+	// Verify new request was made (different request_number)
+	if result1["request_number"] == result3["request_number"] {
+		t.Error("Expected different request_number after TTL expiration")
+	}
+}
+
+// ============== Pattern-Based Caching Tests ==============
+
+func TestCaching_PatternBasedCaching(t *testing.T) {
+	var apiCount, staticCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		if r.URL.Path[:5] == "/api/" {
+			atomic.AddInt64(&apiCount, 1)
+		} else {
+			atomic.AddInt64(&staticCount, 1)
+		}
+		json.NewEncoder(w).Encode(map[string]string{"path": r.URL.Path})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	// Only cache /api/* paths
+	cachingExt, _ := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "1m",
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "1m",
+				"methods": []interface{}{"GET"},
+			},
+		},
+	}, logger)
+
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Multiple requests to /api/ - should be cached
+	for i := 0; i < 3; i++ {
+		resp, _ := client.Get("/api/users", nil)
+		resp.Body.Close()
+	}
+
+	// Multiple requests to /static/ - should NOT be cached (not matching pattern)
+	for i := 0; i < 3; i++ {
+		resp, _ := client.Get("/static/file.js", nil)
+		resp.Body.Close()
+	}
+
+	// API should have only 1 request (cached)
+	if atomic.LoadInt64(&apiCount) != 1 {
+		t.Errorf("Expected 1 API request (cached), got %d", apiCount)
+	}
+
+	// Static should have 3 requests (not cached)
+	if atomic.LoadInt64(&staticCount) != 3 {
+		t.Errorf("Expected 3 static requests (not cached), got %d", staticCount)
+	}
+}
+
+// ============== Method-Specific Caching Tests ==============
+
+func TestCaching_OnlyGETMethodCached(t *testing.T) {
+	var getCount, postCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		if r.Method == "GET" {
+			atomic.AddInt64(&getCount, 1)
+		} else if r.Method == "POST" {
+			atomic.AddInt64(&postCount, 1)
+		}
+		json.NewEncoder(w).Encode(map[string]string{
+			"method": r.Method,
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	cachingExt, _ := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "1m",
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "1m",
+				"methods": []interface{}{"GET"}, // Only GET
+			},
+		},
+	}, logger)
+
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Multiple GET requests - should be cached
+	for i := 0; i < 3; i++ {
+		resp, _ := client.Get("/api/data", nil)
+		resp.Body.Close()
+	}
+
+	// Multiple POST requests - should NOT be cached
+	for i := 0; i < 3; i++ {
+		resp, _ := client.Post("/api/data", []byte(`{}`), map[string]string{
+			"Content-Type": "application/json",
+		})
+		resp.Body.Close()
+	}
+
+	if atomic.LoadInt64(&getCount) != 1 {
+		t.Errorf("Expected 1 GET request (cached), got %d", getCount)
+	}
+
+	if atomic.LoadInt64(&postCount) != 3 {
+		t.Errorf("Expected 3 POST requests (not cached), got %d", postCount)
+	}
+}
+
+// ============== Different Paths Different Cache Keys ==============
+
+func TestCaching_DifferentPathsDifferentCacheKeys(t *testing.T) {
+	var requestCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		count := atomic.AddInt64(&requestCount, 1)
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"path":           r.URL.Path,
+			"request_number": count,
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	cachingExt, _ := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "1m",
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "1m",
+			},
+		},
+	}, logger)
+
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Request different paths
+	paths := []string{"/api/users", "/api/posts", "/api/comments"}
+
+	for _, path := range paths {
+		resp, _ := client.Get(path, nil)
+		resp.Body.Close()
+	}
+
+	// Each path should result in a separate backend request
+	if atomic.LoadInt64(&requestCount) != 3 {
+		t.Errorf("Expected 3 backend requests (one per path), got %d", requestCount)
+	}
+
+	// Request same paths again - all should be cached
+	for _, path := range paths {
+		resp, _ := client.Get(path, nil)
+		cacheHeader := resp.Header.Get("X-Cache")
+		resp.Body.Close()
+
+		if cacheHeader != "HIT" {
+			t.Errorf("Expected X-Cache: HIT for %s, got %q", path, cacheHeader)
+		}
+	}
+
+	// No additional backend requests
+	if atomic.LoadInt64(&requestCount) != 3 {
+		t.Errorf("Expected still 3 backend requests after cache hits, got %d", requestCount)
+	}
+}
+
+// ============== Query String Affects Cache Key ==============
+
+func TestCaching_QueryStringAffectsCacheKey(t *testing.T) {
+	var requestCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		count := atomic.AddInt64(&requestCount, 1)
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"query":          r.URL.RawQuery,
+			"request_number": count,
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	cachingExt, _ := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "1m",
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "1m",
+			},
+		},
+	}, logger)
+
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Different query strings = different cache keys
+	queries := []string{
+		"/api/search?q=hello",
+		"/api/search?q=world",
+		"/api/search?q=test",
+	}
+
+	for _, query := range queries {
+		resp, _ := client.Get(query, nil)
+		resp.Body.Close()
+	}
+
+	// Each unique query should result in a separate backend request
+	if atomic.LoadInt64(&requestCount) != 3 {
+		t.Errorf("Expected 3 backend requests (one per query), got %d", requestCount)
+	}
+
+	// Same query again should be cached
+	resp, _ := client.Get("/api/search?q=hello", nil)
+	cacheHeader := resp.Header.Get("X-Cache")
+	resp.Body.Close()
+
+	if cacheHeader != "HIT" {
+		t.Errorf("Expected X-Cache: HIT for repeated query, got %q", cacheHeader)
+	}
+}
+
+// ============== Cache Does Not Store Error Responses ==============
+
+func TestCaching_DoesNotCacheErrors(t *testing.T) {
+	var requestCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		atomic.AddInt64(&requestCount, 1)
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusInternalServerError)
+		json.NewEncoder(w).Encode(map[string]string{"error": "internal error"})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	cachingExt, _ := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "1m",
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "1m",
+			},
+		},
+	}, logger)
+
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Multiple requests to error endpoint
+	for i := 0; i < 3; i++ {
+		resp, _ := client.Get("/api/error", nil)
+		resp.Body.Close()
+	}
+
+	// All requests should reach backend (errors not cached)
+	if atomic.LoadInt64(&requestCount) != 3 {
+		t.Errorf("Expected 3 backend requests (errors not cached), got %d", requestCount)
+	}
+}
+
+// ============== Concurrent Cache Access ==============
+
+func TestCaching_ConcurrentAccess(t *testing.T) {
+	var requestCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		// Small delay to increase chance of race conditions
+		time.Sleep(10 * time.Millisecond)
+		count := atomic.AddInt64(&requestCount, 1)
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"request_number": count,
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	cachingExt, _ := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "1m",
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "1m",
+			},
+		},
+	}, logger)
+
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	const numRequests = 20
+	results := make(chan error, numRequests)
+
+	// Make first request to populate cache
+	client := NewHTTPClient(server.URL)
+	resp, _ := client.Get("/api/concurrent", nil)
+	resp.Body.Close()
+
+	// Now many concurrent requests should all hit cache
+	for i := 0; i < numRequests; i++ {
+		go func(n int) {
+			client := NewHTTPClient(server.URL)
+			resp, err := client.Get("/api/concurrent", nil)
+			if err != nil {
+				results <- err
+				return
+			}
+
+			cacheHeader := resp.Header.Get("X-Cache")
+			resp.Body.Close()
+
+			if cacheHeader != "HIT" {
+				results <- fmt.Errorf("request %d: expected HIT, got %s", n, cacheHeader)
+				return
+			}
+			results <- nil
+		}(i)
+	}
+
+	// Collect results
+	var errors []error
+	for i := 0; i < numRequests; i++ {
+		if err := <-results; err != nil {
+			errors = append(errors, err)
+		}
+	}
+
+	if len(errors) > 0 {
+		t.Errorf("Got %d errors in concurrent cache access: %v", len(errors), errors[:min(5, len(errors))])
+	}
+
+	// Only 1 request should reach backend (the initial one)
+	if atomic.LoadInt64(&requestCount) != 1 {
+		t.Errorf("Expected 1 backend request, got %d", requestCount)
+	}
+}
+
+// ============== Multiple Cache Patterns ==============
+
+func TestCaching_MultipleCachePatterns(t *testing.T) {
+	var apiCount, staticCount int64
+
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		if len(r.URL.Path) >= 5 && r.URL.Path[:5] == "/api/" {
+			atomic.AddInt64(&apiCount, 1)
+		} else if len(r.URL.Path) >= 8 && r.URL.Path[:8] == "/static/" {
+			atomic.AddInt64(&staticCount, 1)
+		}
+		json.NewEncoder(w).Encode(map[string]string{"path": r.URL.Path})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+
+	cachingExt, _ := extension.NewCachingExtension(map[string]interface{}{
+		"default_ttl": "1m",
+		"cache_patterns": []interface{}{
+			map[string]interface{}{
+				"pattern": "^/api/.*",
+				"ttl":     "30s",
+				"methods": []interface{}{"GET"},
+			},
+			map[string]interface{}{
+				"pattern": "^/static/.*",
+				"ttl":     "1h", // Static files cached longer
+				"methods": []interface{}{"GET"},
+			},
+		},
+	}, logger)
+
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{cachingExt, routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Multiple requests to both patterns
+	for i := 0; i < 3; i++ {
+		resp1, _ := client.Get("/api/data", nil)
+		resp1.Body.Close()
+
+		resp2, _ := client.Get("/static/app.js", nil)
+		resp2.Body.Close()
+	}
+
+	// Both should be cached (1 request each)
+	if atomic.LoadInt64(&apiCount) != 1 {
+		t.Errorf("Expected 1 API request, got %d", apiCount)
+	}
+
+	if atomic.LoadInt64(&staticCount) != 1 {
+		t.Errorf("Expected 1 static request, got %d", staticCount)
+	}
+}
diff --git a/go/tests/integration/routing_test.go b/go/tests/integration/routing_test.go
new file mode 100644
index 0000000..334dcd2
--- /dev/null
+++ b/go/tests/integration/routing_test.go
@@ -0,0 +1,494 @@
+package integration
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/konduktor/konduktor/internal/extension"
+)
+
+// ============== Route Priority Tests ==============
+
+func TestRouting_ExactMatchPriority(t *testing.T) {
+	// Exact match should have highest priority
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode(map[string]string{
+			"path":   r.URL.Path,
+			"source": "default",
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+	routingExt, err := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			// Exact match - highest priority
+			"=/api/status": map[string]interface{}{
+				"return":       "200 exact-match",
+				"content_type": "text/plain",
+			},
+			// Regex that also matches /api/status
+			"~^/api/.*": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+	if err != nil {
+		t.Fatalf("Failed to create routing extension: %v", err)
+	}
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Test exact match route - should return static response
+	resp, err := client.Get("/api/status", nil)
+	if err != nil {
+		t.Fatalf("Request failed: %v", err)
+	}
+	defer resp.Body.Close()
+
+	AssertStatus(t, resp, http.StatusOK)
+
+	body := ReadBody(t, resp)
+	if string(body) != "exact-match" {
+		t.Errorf("Expected 'exact-match', got %q", string(body))
+	}
+
+	// Regex route should be used for other /api/* paths
+	resp2, err := client.Get("/api/other", nil)
+	if err != nil {
+		t.Fatalf("Request failed: %v", err)
+	}
+	defer resp2.Body.Close()
+
+	AssertStatus(t, resp2, http.StatusOK)
+
+	// Verify it went to backend
+	if backend.RequestCount() != 1 {
+		t.Errorf("Expected 1 backend request, got %d", backend.RequestCount())
+	}
+}
+
+// ============== Case Sensitivity Tests ==============
+
+func TestRouting_CaseSensitiveRegex(t *testing.T) {
+	logger := createTestLogger(t)
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			// Case-sensitive regex (~)
+			"~^/API/test$": map[string]interface{}{
+				"return":       "200 case-sensitive",
+				"content_type": "text/plain",
+			},
+			"__default__": map[string]interface{}{
+				"return":       "200 default",
+				"content_type": "text/plain",
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Exact case match should work
+	resp, err := client.Get("/API/test", nil)
+	if err != nil {
+		t.Fatalf("Request failed: %v", err)
+	}
+	defer resp.Body.Close()
+
+	body := ReadBody(t, resp)
+	if string(body) != "case-sensitive" {
+		t.Errorf("Expected 'case-sensitive' for /API/test, got %q", string(body))
+	}
+
+	// Different case should NOT match
+	resp2, err := client.Get("/api/test", nil)
+	if err != nil {
+		t.Fatalf("Request failed: %v", err)
+	}
+	defer resp2.Body.Close()
+
+	body2 := ReadBody(t, resp2)
+	if string(body2) != "default" {
+		t.Errorf("Expected 'default' for /api/test (case mismatch), got %q", string(body2))
+	}
+}
+
+func TestRouting_CaseInsensitiveRegex(t *testing.T) {
+	logger := createTestLogger(t)
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			// Case-insensitive regex (~*)
+			"~*^/api/test$": map[string]interface{}{
+				"return":       "200 case-insensitive",
+				"content_type": "text/plain",
+			},
+			"__default__": map[string]interface{}{
+				"return":       "200 default",
+				"content_type": "text/plain",
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	testCases := []struct {
+		path     string
+		expected string
+	}{
+		{"/api/test", "case-insensitive"},
+		{"/API/test", "case-insensitive"},
+		{"/Api/Test", "case-insensitive"},
+		{"/API/TEST", "case-insensitive"},
+		{"/api/other", "default"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.path, func(t *testing.T) {
+			resp, err := client.Get(tc.path, nil)
+			if err != nil {
+				t.Fatalf("Request failed: %v", err)
+			}
+			defer resp.Body.Close()
+
+			body := ReadBody(t, resp)
+			if string(body) != tc.expected {
+				t.Errorf("Expected %q for %s, got %q", tc.expected, tc.path, string(body))
+			}
+		})
+	}
+}
+
+// ============== Default Route Tests ==============
+
+func TestRouting_DefaultRoute(t *testing.T) {
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode(map[string]string{
+			"handler": "default",
+			"path":    r.URL.Path,
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"=/specific": map[string]interface{}{
+				"return":       "200 specific",
+				"content_type": "text/plain",
+			},
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Non-matching paths should go to default
+	paths := []string{"/", "/random", "/path/to/resource", "/api/v1/users"}
+
+	for _, path := range paths {
+		t.Run(path, func(t *testing.T) {
+			resp, err := client.Get(path, nil)
+			if err != nil {
+				t.Fatalf("Request failed: %v", err)
+			}
+			defer resp.Body.Close()
+
+			AssertStatus(t, resp, http.StatusOK)
+
+			var result map[string]string
+			json.NewDecoder(resp.Body).Decode(&result)
+
+			if result["handler"] != "default" {
+				t.Errorf("Expected default handler, got %v", result["handler"])
+			}
+		})
+	}
+}
+
+// ============== Return Directive Tests ==============
+
+func TestRouting_ReturnDirective(t *testing.T) {
+	logger := createTestLogger(t)
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"=/health": map[string]interface{}{
+				"return":       "200 OK",
+				"content_type": "text/plain",
+			},
+			"=/status": map[string]interface{}{
+				"return":       "200 {\"status\": \"healthy\"}",
+				"content_type": "application/json",
+			},
+			"=/forbidden": map[string]interface{}{
+				"return":       "404 Not Found",
+				"content_type": "text/plain",
+			},
+			"__default__": map[string]interface{}{
+				"return":       "200 default",
+				"content_type": "text/plain",
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	testCases := []struct {
+		path           string
+		expectedStatus int
+		expectedBody   string
+		contentType    string
+	}{
+		{"/health", 200, "OK", "text/plain"},
+		{"/status", 200, `{"status": "healthy"}`, "application/json"},
+		{"/forbidden", 404, "Not Found", "text/plain"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.path, func(t *testing.T) {
+			resp, err := client.Get(tc.path, nil)
+			if err != nil {
+				t.Fatalf("Request failed: %v", err)
+			}
+			defer resp.Body.Close()
+
+			AssertStatus(t, resp, tc.expectedStatus)
+			AssertHeaderContains(t, resp, "Content-Type", tc.contentType)
+
+			body := ReadBody(t, resp)
+			if string(body) != tc.expectedBody {
+				t.Errorf("Expected body %q, got %q", tc.expectedBody, string(body))
+			}
+		})
+	}
+}
+
+// ============== Multiple Regex Routes Tests ==============
+
+func TestRouting_MultipleRegexRoutes(t *testing.T) {
+	logger := createTestLogger(t)
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"~^/api/v1/.*": map[string]interface{}{
+				"return":       "200 v1",
+				"content_type": "text/plain",
+			},
+			"~^/api/v2/.*": map[string]interface{}{
+				"return":       "200 v2",
+				"content_type": "text/plain",
+			},
+			"~^/api/.*": map[string]interface{}{
+				"return":       "200 api-generic",
+				"content_type": "text/plain",
+			},
+			"__default__": map[string]interface{}{
+				"return":       "200 default",
+				"content_type": "text/plain",
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	testCases := []struct {
+		path     string
+		expected string
+	}{
+		{"/api/v1/users", "v1"},
+		{"/api/v2/users", "v2"},
+		{"/api/v3/users", "api-generic"},
+		{"/other", "default"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.path, func(t *testing.T) {
+			resp, err := client.Get(tc.path, nil)
+			if err != nil {
+				t.Fatalf("Request failed: %v", err)
+			}
+			defer resp.Body.Close()
+
+			body := ReadBody(t, resp)
+			if string(body) != tc.expected {
+				t.Errorf("Expected %q for %s, got %q", tc.expected, tc.path, string(body))
+			}
+		})
+	}
+}
+
+// ============== Regex with Named Groups ==============
+
+func TestRouting_RegexNamedGroups(t *testing.T) {
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode(map[string]string{
+			"path": r.URL.Path,
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"~^/users/(?P<userId>\\d+)/posts/(?P<postId>\\d+)$": map[string]interface{}{
+				"proxy_pass": backend.URL() + "/api/v2/users/{userId}/posts/{postId}",
+			},
+			"~^/items/(?P<category>[a-z]+)/(?P<id>\\d+)$": map[string]interface{}{
+				"proxy_pass": backend.URL() + "/catalog/{category}/item/{id}",
+			},
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	testCases := []struct {
+		requestPath  string
+		expectedPath string
+	}{
+		{"/users/123/posts/456", "/api/v2/users/123/posts/456"},
+		{"/items/electronics/789", "/catalog/electronics/item/789"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.requestPath, func(t *testing.T) {
+			resp, err := client.Get(tc.requestPath, nil)
+			if err != nil {
+				t.Fatalf("Request failed: %v", err)
+			}
+			defer resp.Body.Close()
+
+			AssertStatus(t, resp, http.StatusOK)
+
+			lastReq := backend.LastRequest()
+			if lastReq == nil {
+				t.Fatal("No request received by backend")
+			}
+
+			if lastReq.Path != tc.expectedPath {
+				t.Errorf("Expected backend path %s, got %s", tc.expectedPath, lastReq.Path)
+			}
+		})
+	}
+}
+
+// ============== No Matching Route Tests ==============
+
+func TestRouting_NoMatchingRoute(t *testing.T) {
+	logger := createTestLogger(t)
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"=/specific": map[string]interface{}{
+				"return":       "200 specific",
+				"content_type": "text/plain",
+			},
+			// No default route
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	// Request to non-matching path should return 404
+	resp, err := client.Get("/other", nil)
+	if err != nil {
+		t.Fatalf("Request failed: %v", err)
+	}
+	defer resp.Body.Close()
+
+	AssertStatus(t, resp, http.StatusNotFound)
+}
+
+// ============== Headers in Return Tests ==============
+
+func TestRouting_CustomHeaders(t *testing.T) {
+	backend := StartBackend(func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode(map[string]string{
+			"x-custom-header": r.Header.Get("X-Custom-Header"),
+			"x-api-version":   r.Header.Get("X-API-Version"),
+		})
+	})
+	defer backend.Close()
+
+	logger := createTestLogger(t)
+	routingExt, _ := extension.NewRoutingExtension(map[string]interface{}{
+		"regex_locations": map[string]interface{}{
+			"__default__": map[string]interface{}{
+				"proxy_pass": backend.URL(),
+				"headers": []interface{}{
+					"X-Custom-Header: custom-value",
+					"X-API-Version: v1",
+				},
+			},
+		},
+	}, logger)
+
+	server := StartTestServer(t, &ServerConfig{
+		Extensions: []extension.Extension{routingExt},
+	})
+	defer server.Close()
+
+	client := NewHTTPClient(server.URL)
+
+	resp, err := client.Get("/test", nil)
+	if err != nil {
+		t.Fatalf("Request failed: %v", err)
+	}
+	defer resp.Body.Close()
+
+	var result map[string]string
+	json.NewDecoder(resp.Body).Decode(&result)
+
+	if result["x-custom-header"] != "custom-value" {
+		t.Errorf("Expected X-Custom-Header=custom-value, got %v", result["x-custom-header"])
+	}
+
+	if result["x-api-version"] != "v1" {
+		t.Errorf("Expected X-API-Version=v1, got %v", result["x-api-version"])
+	}
+}