diff --git a/src/common/decorators/core/bind.decorator.ts b/src/common/decorators/core/bind.decorator.ts
index c550b52886a..c62dd84b470 100644
--- a/src/common/decorators/core/bind.decorator.ts
+++ b/src/common/decorators/core/bind.decorator.ts
@@ -3,7 +3,7 @@
  * Useful when the language doesn't provide a 'Parameter Decorators' feature (vanilla JavaScript)
  * @param  {} ...decorators
  */
-export function Bind(...decorators) {
+export function Bind(...decorators: any[]) {
   return (target: object, key, descriptor) => {
     decorators.forEach((fn, index) => fn(target, key, index));
     return descriptor;
diff --git a/src/common/decorators/core/catch.decorator.ts b/src/common/decorators/core/catch.decorator.ts
index 29cebfa24ea..675d1bdd96b 100644
--- a/src/common/decorators/core/catch.decorator.ts
+++ b/src/common/decorators/core/catch.decorator.ts
@@ -5,7 +5,7 @@ import { FILTER_CATCH_EXCEPTIONS } from '../../constants';
  * Defines the Exceptions Filter. Takes set of exception types as an argument which has to be caught by this Filter.
  * The class should implement the `ExceptionFilter` interface.
  */
-export function Catch(...exceptions): ClassDecorator {
+export function Catch(...exceptions: any[]): ClassDecorator {
   return (target: object) => {
     Reflect.defineMetadata(FILTER_CATCH_EXCEPTIONS, exceptions, target);
   };
diff --git a/src/common/decorators/core/dependencies.decorator.ts b/src/common/decorators/core/dependencies.decorator.ts
index 5c702df837a..8a0473aa0b9 100644
--- a/src/common/decorators/core/dependencies.decorator.ts
+++ b/src/common/decorators/core/dependencies.decorator.ts
@@ -1,12 +1,12 @@
 import 'reflect-metadata';
 import { PARAMTYPES_METADATA } from '../../constants';
 
-export function flatten(arr) {
+export function flatten(arr: any[]) {
   const flat = [].concat(...arr);
   return flat.some(Array.isArray) ? flatten(flat) : flat;
 };
 
-export const Dependencies = (...dependencies): ClassDecorator => {
+export const Dependencies = (...dependencies: any[]): ClassDecorator => {
   const flattenDeps = flatten(dependencies);
   return (target: object) => {
     Reflect.defineMetadata(PARAMTYPES_METADATA, flattenDeps, target);
diff --git a/src/common/decorators/core/exception-filters.decorator.ts b/src/common/decorators/core/exception-filters.decorator.ts
index d5652ec2846..363e1c9b759 100644
--- a/src/common/decorators/core/exception-filters.decorator.ts
+++ b/src/common/decorators/core/exception-filters.decorator.ts
@@ -2,18 +2,19 @@ import 'reflect-metadata';
 import { EXCEPTION_FILTERS_METADATA } from '../../constants';
 import { Logger } from '@nestjs/common';
 import { ExceptionFilter } from '../../index';
+import { extendArrayMetadata } from '../../utils/extend-metadata.util';
 
 const defineFiltersMetadata = (...filters: ExceptionFilter[]) => {
   return (target: object, key?, descriptor?) => {
     if (descriptor) {
-      Reflect.defineMetadata(
+      extendArrayMetadata(
         EXCEPTION_FILTERS_METADATA,
         filters,
         descriptor.value,
       );
       return descriptor;
     }
-    Reflect.defineMetadata(EXCEPTION_FILTERS_METADATA, filters, target);
+    extendArrayMetadata(EXCEPTION_FILTERS_METADATA, filters, target);
     return target;
   };
 };
diff --git a/src/common/decorators/core/inject.decorator.ts b/src/common/decorators/core/inject.decorator.ts
index 946433807d8..9e40dd5b428 100644
--- a/src/common/decorators/core/inject.decorator.ts
+++ b/src/common/decorators/core/inject.decorator.ts
@@ -6,7 +6,7 @@ import { isFunction } from '../../utils/shared.utils';
  * Injects provider which has to be available in the current injector (module) scope.
  * Providers are recognized by types or tokens.
  */
-export function Inject(token): ParameterDecorator {
+export function Inject(token: any): ParameterDecorator {
   return (target, key, index) => {
     const args = Reflect.getMetadata(SELF_DECLARED_DEPS_METADATA, target) || [];
     const type = isFunction(token) ? token.name : token;
diff --git a/src/common/decorators/core/use-guards.decorator.ts b/src/common/decorators/core/use-guards.decorator.ts
index fd2d9ad89ad..a7521774799 100644
--- a/src/common/decorators/core/use-guards.decorator.ts
+++ b/src/common/decorators/core/use-guards.decorator.ts
@@ -1,4 +1,5 @@
 import { GUARDS_METADATA } from '../../constants';
+import { extendArrayMetadata } from '../../utils/extend-metadata.util';
 
 /**
  * Binds guards to the particular context.
@@ -10,13 +11,13 @@ import { GUARDS_METADATA } from '../../constants';
  *
  * @param  {} ...guards (types)
  */
-export function UseGuards(...guards) {
+export function UseGuards(...guards: any[]) {
   return (target: object, key?, descriptor?) => {
     if (descriptor) {
-      Reflect.defineMetadata(GUARDS_METADATA, guards, descriptor.value);
+      extendArrayMetadata(GUARDS_METADATA, guards, descriptor.value);
       return descriptor;
     }
-    Reflect.defineMetadata(GUARDS_METADATA, guards, target);
+    extendArrayMetadata(GUARDS_METADATA, guards, target);
     return target;
   };
 }
diff --git a/src/common/decorators/core/use-interceptors.decorator.ts b/src/common/decorators/core/use-interceptors.decorator.ts
index 963eee53069..0b160a55ed3 100644
--- a/src/common/decorators/core/use-interceptors.decorator.ts
+++ b/src/common/decorators/core/use-interceptors.decorator.ts
@@ -1,4 +1,5 @@
 import { INTERCEPTORS_METADATA } from '../../constants';
+import { extendArrayMetadata } from '../../utils/extend-metadata.util';
 
 /**
  * Binds interceptors to the particular context.
@@ -10,17 +11,17 @@ import { INTERCEPTORS_METADATA } from '../../constants';
  *
  * @param  {} ...interceptors (types)
  */
-export function UseInterceptors(...interceptors) {
+export function UseInterceptors(...interceptors: any[]) {
   return (target: object, key?, descriptor?) => {
     if (descriptor) {
-      Reflect.defineMetadata(
+      extendArrayMetadata(
         INTERCEPTORS_METADATA,
         interceptors,
         descriptor.value,
       );
       return descriptor;
     }
-    Reflect.defineMetadata(INTERCEPTORS_METADATA, interceptors, target);
+    extendArrayMetadata(INTERCEPTORS_METADATA, interceptors, target);
     return target;
   };
 }
diff --git a/src/common/decorators/core/use-pipes.decorator.ts b/src/common/decorators/core/use-pipes.decorator.ts
index 06ff8bb495e..17b41de1a8b 100644
--- a/src/common/decorators/core/use-pipes.decorator.ts
+++ b/src/common/decorators/core/use-pipes.decorator.ts
@@ -1,5 +1,6 @@
 import { PipeTransform } from '../../interfaces/index';
 import { PIPES_METADATA } from '../../constants';
+import { extendArrayMetadata } from '../../utils/extend-metadata.util';
 
 /**
  * Binds pipes to the particular context.
@@ -14,10 +15,10 @@ import { PIPES_METADATA } from '../../constants';
 export function UsePipes(...pipes: PipeTransform<any>[]) {
   return (target: object, key?, descriptor?) => {
     if (descriptor) {
-      Reflect.defineMetadata(PIPES_METADATA, pipes, descriptor.value);
+      extendArrayMetadata(PIPES_METADATA, pipes, descriptor.value);
       return descriptor;
     }
-    Reflect.defineMetadata(PIPES_METADATA, pipes, target);
+    extendArrayMetadata(PIPES_METADATA, pipes, target);
     return target;
   };
 }
diff --git a/src/common/interfaces/exceptions/exception-filter.interface.ts b/src/common/interfaces/exceptions/exception-filter.interface.ts
index 8d37e3c8353..e83ee2e43ca 100644
--- a/src/common/interfaces/exceptions/exception-filter.interface.ts
+++ b/src/common/interfaces/exceptions/exception-filter.interface.ts
@@ -1,3 +1,3 @@
-export interface ExceptionFilter {
-  catch(exception, response);
+export interface ExceptionFilter<T = any, R = any> {
+  catch(exception: T, response: R);
 }
diff --git a/src/common/interfaces/exceptions/rpc-exception-filter.interface.ts b/src/common/interfaces/exceptions/rpc-exception-filter.interface.ts
index 22f79627302..b292036bb7c 100644
--- a/src/common/interfaces/exceptions/rpc-exception-filter.interface.ts
+++ b/src/common/interfaces/exceptions/rpc-exception-filter.interface.ts
@@ -1,5 +1,5 @@
 import { Observable } from 'rxjs/Observable';
 
-export interface RpcExceptionFilter {
-  catch(exception): Observable<any>;
+export interface RpcExceptionFilter<T = any, R = any> {
+  catch(exception: T): Observable<R>;
 }
diff --git a/src/common/interfaces/exceptions/ws-exception-filter.interface.ts b/src/common/interfaces/exceptions/ws-exception-filter.interface.ts
index e13c3849981..9e7ff81556d 100644
--- a/src/common/interfaces/exceptions/ws-exception-filter.interface.ts
+++ b/src/common/interfaces/exceptions/ws-exception-filter.interface.ts
@@ -1,3 +1,3 @@
-export interface WsExceptionFilter {
-  catch(exception, client);
+export interface WsExceptionFilter<T = any, R = any> {
+  catch(exception: T, client: R);
 }
diff --git a/src/common/interfaces/features/nest-interceptor.interface.ts b/src/common/interfaces/features/nest-interceptor.interface.ts
index c44e99ac29f..e302a11b124 100644
--- a/src/common/interfaces/features/nest-interceptor.interface.ts
+++ b/src/common/interfaces/features/nest-interceptor.interface.ts
@@ -1,10 +1,10 @@
 import { Observable } from 'rxjs/Observable';
 import { ExecutionContext } from './execution-context.interface';
 
-export interface NestInterceptor {
+export interface NestInterceptor<T = any, R = any> {
   intercept(
     dataOrRequest,
     context: ExecutionContext,
-    stream$: Observable<any>,
-  ): Observable<any> | Promise<Observable<any>>;
+    stream$: Observable<T>,
+  ): Observable<R> | Promise<Observable<R>>;
 }
diff --git a/src/common/interfaces/features/pipe-transform.interface.ts b/src/common/interfaces/features/pipe-transform.interface.ts
index 721a632e738..51f87e6bb02 100644
--- a/src/common/interfaces/features/pipe-transform.interface.ts
+++ b/src/common/interfaces/features/pipe-transform.interface.ts
@@ -1,6 +1,6 @@
 import { Paramtype } from './paramtype.interface';
 
-export type Transform<T> = (value: T, metadata: ArgumentMetadata) => any;
+export type Transform<T = any> = (value: T, metadata: ArgumentMetadata) => any;
 
 export interface ArgumentMetadata {
   type: Paramtype;
@@ -8,6 +8,6 @@ export interface ArgumentMetadata {
   data?: string;
 }
 
-export interface PipeTransform<T> {
-  transform(value: T, metadata: ArgumentMetadata): any;
+export interface PipeTransform<T = any, R = any> {
+  transform(value: T, metadata: ArgumentMetadata): R;
 }
diff --git a/src/common/interfaces/middlewares/middleware-config-proxy.interface.ts b/src/common/interfaces/middlewares/middleware-config-proxy.interface.ts
index 042f745085c..67c40651141 100644
--- a/src/common/interfaces/middlewares/middleware-config-proxy.interface.ts
+++ b/src/common/interfaces/middlewares/middleware-config-proxy.interface.ts
@@ -18,7 +18,7 @@ export interface MiddlewareConfigProxy {
    * method: RequestMethod;
    * ```
    *
-   * When you passe Controller class, Nest will attach middleware to every HTTP route handler inside this controller.
+   * When you pass Controller class, Nest will attach middleware to every HTTP route handler inside this controller.
    *
    * @param  {} ...routes
    * @returns MiddlewaresConsumer
diff --git a/src/common/interfaces/websockets/web-socket-adapter.interface.ts b/src/common/interfaces/websockets/web-socket-adapter.interface.ts
index 088c3bb5fb4..aded83655aa 100644
--- a/src/common/interfaces/websockets/web-socket-adapter.interface.ts
+++ b/src/common/interfaces/websockets/web-socket-adapter.interface.ts
@@ -1,7 +1,7 @@
 import { Observable } from 'rxjs/Observable';
 
-export interface WebSocketAdapter {
-  create(port: number, options?: any & { namespace?: string; server?: any });
+export interface WebSocketAdapter<T = any> {
+  create(port: number, options?: T);
   bindClientConnect(server, callback: (...args) => void);
   bindClientDisconnect?(client, callback: (...args) => void);
   bindMessageHandlers(
diff --git a/src/common/test/decorators/use-guards.decorator.spec.ts b/src/common/test/decorators/use-guards.decorator.spec.ts
index adeb814aefd..d7ae0e9289e 100644
--- a/src/common/test/decorators/use-guards.decorator.spec.ts
+++ b/src/common/test/decorators/use-guards.decorator.spec.ts
@@ -14,6 +14,12 @@ describe('@UseGuards', () => {
     public static test() {}
   }
 
+  class Test2 {
+    @UseGuards(...(guards as any))
+    @UseGuards(...(guards as any))
+    public static test() {}
+  }
+
   it('should enhance class with expected guards array', () => {
     const metadata = Reflect.getMetadata(GUARDS_METADATA, Test);
     expect(metadata).to.be.eql(guards);
@@ -23,4 +29,9 @@ describe('@UseGuards', () => {
     const metadata = Reflect.getMetadata(GUARDS_METADATA, TestWithMethod.test);
     expect(metadata).to.be.eql(guards);
   });
+
+  it('should enhance class with multiple guards array', () => {
+    const metadata = Reflect.getMetadata(GUARDS_METADATA, Test2.test);
+    expect(metadata).to.be.eql(guards.concat(guards));
+  });
 });
diff --git a/src/common/utils/extend-metadata.util.ts b/src/common/utils/extend-metadata.util.ts
new file mode 100644
index 00000000000..49d27619ee1
--- /dev/null
+++ b/src/common/utils/extend-metadata.util.ts
@@ -0,0 +1,9 @@
+export function extendArrayMetadata<T extends Array<any>>(
+  key: string,
+  metadata: T,
+  target,
+) {
+  const previousValue = Reflect.getMetadata(key, target) || [];
+  const value = [...previousValue, ...metadata];
+  Reflect.defineMetadata(key, value, target);
+}
diff --git a/src/microservices/interfaces/packet.interface.ts b/src/microservices/interfaces/packet.interface.ts
index 8efb36d4daa..b82377f19dc 100644
--- a/src/microservices/interfaces/packet.interface.ts
+++ b/src/microservices/interfaces/packet.interface.ts
@@ -9,6 +9,6 @@ export interface ReadPacket<T = any> {
 
 export interface WritePacket<T = any> {
   err?: any;
-  response?: any;
+  response?: T;
   isDisposed?: boolean;
 }
\ No newline at end of file
diff --git a/src/microservices/utils/pattern.decorator.ts b/src/microservices/utils/pattern.decorator.ts
index 1867ae0fd92..14b97722a19 100644
--- a/src/microservices/utils/pattern.decorator.ts
+++ b/src/microservices/utils/pattern.decorator.ts
@@ -5,8 +5,8 @@ import { PatternMetadata } from '../interfaces/pattern-metadata.interface';
 /**
  * Subscribes to incoming messages which fulfils chosen pattern.
  */
-export const MessagePattern = (
-  metadata?: PatternMetadata | string,
+export const MessagePattern = <T = PatternMetadata | string>(
+  metadata?: T,
 ): MethodDecorator => {
   return (target, key, descriptor: PropertyDescriptor) => {
     Reflect.defineMetadata(PATTERN_METADATA, metadata, descriptor.value);
diff --git a/src/websockets/interfaces/on-gateway-connection.interface.ts b/src/websockets/interfaces/on-gateway-connection.interface.ts
index 324f7f6b754..da622ff74fe 100644
--- a/src/websockets/interfaces/on-gateway-connection.interface.ts
+++ b/src/websockets/interfaces/on-gateway-connection.interface.ts
@@ -1,3 +1,3 @@
-export interface OnGatewayConnection {
-  handleConnection(client: any);
+export interface OnGatewayConnection<T = any> {
+  handleConnection(client: T);
 }
diff --git a/src/websockets/interfaces/on-gateway-disconnect.interface.ts b/src/websockets/interfaces/on-gateway-disconnect.interface.ts
index 2c2cc9320c1..aa715e46688 100644
--- a/src/websockets/interfaces/on-gateway-disconnect.interface.ts
+++ b/src/websockets/interfaces/on-gateway-disconnect.interface.ts
@@ -1,3 +1,3 @@
-export interface OnGatewayDisconnect {
-  handleDisconnect(client: any);
+export interface OnGatewayDisconnect<T = any> {
+  handleDisconnect(client: T);
 }
diff --git a/src/websockets/interfaces/on-gateway-init.interface.ts b/src/websockets/interfaces/on-gateway-init.interface.ts
index d0e5d9be6ab..379f860f2c9 100644
--- a/src/websockets/interfaces/on-gateway-init.interface.ts
+++ b/src/websockets/interfaces/on-gateway-init.interface.ts
@@ -1,3 +1,3 @@
-export interface OnGatewayInit {
-  afterInit(server: any);
+export interface OnGatewayInit<T = any> {
+  afterInit(server: T);
 }
diff --git a/src/websockets/interfaces/ws-response.interface.ts b/src/websockets/interfaces/ws-response.interface.ts
index 2df913fbd9b..04e815cbf7f 100644
--- a/src/websockets/interfaces/ws-response.interface.ts
+++ b/src/websockets/interfaces/ws-response.interface.ts
@@ -1,4 +1,4 @@
-export interface WsResponse<T> {
+export interface WsResponse<T = any> {
   event: string;
   data: T;
 }
diff --git a/src/websockets/utils/gateway-server.decorator.ts b/src/websockets/utils/gateway-server.decorator.ts
index 8bf273988c0..6a962595e1e 100644
--- a/src/websockets/utils/gateway-server.decorator.ts
+++ b/src/websockets/utils/gateway-server.decorator.ts
@@ -2,7 +2,7 @@ import 'reflect-metadata';
 import { GATEWAY_SERVER_METADATA } from '../constants';
 
 /**
- * Attaches a native Web Socket Server to the given property.
+ * Attaches native Web Socket Server to a given property.
  */
 export const WebSocketServer = (): PropertyDecorator => {
   return (target: object, propertyKey: string | symbol) => {
diff --git a/src/websockets/utils/subscribe-message.decorator.ts b/src/websockets/utils/subscribe-message.decorator.ts
index bd05424cfb4..859e57f8bdf 100644
--- a/src/websockets/utils/subscribe-message.decorator.ts
+++ b/src/websockets/utils/subscribe-message.decorator.ts
@@ -3,10 +3,10 @@ import { MESSAGE_MAPPING_METADATA, MESSAGE_METADATA } from '../constants';
 import { isObject, isUndefined } from '@nestjs/common/utils/shared.utils';
 
 /**
- * Subscribes to messages which fulfils chosen pattern.
+ * Subscribes to messages that fulfils chosen pattern.
  */
-export const SubscribeMessage = (
-  message: any,
+export const SubscribeMessage = <T = any>(
+  message: T,
 ): MethodDecorator => {
   return (target, key, descriptor: PropertyDescriptor) => {
     Reflect.defineMetadata(MESSAGE_MAPPING_METADATA, true, descriptor.value);