diff --git a/src/axios/cache.ts b/src/axios/cache.ts
index 6d95be1b..3387ab50 100644
--- a/src/axios/cache.ts
+++ b/src/axios/cache.ts
@@ -1,8 +1,8 @@
 import { AxiosInstance } from 'axios';
+import { defaultHeaderInterpreter } from '../header';
 import { applyRequestInterceptor } from '../interceptors/request';
 import { applyResponseInterceptor } from '../interceptors/response';
 import { MemoryStorage } from '../storage/memory';
-import { defaultHeaderInterpreter } from '../header';
 import { defaultKeyGenerator } from '../util/key-generator';
 import CacheInstance, { AxiosCacheInstance, CacheProperties } from './types';
 
@@ -16,7 +16,7 @@ export function createCache(
   axiosCache.generateKey = options.generateKey || defaultKeyGenerator;
   axiosCache.waiting = options.waiting || {};
   axiosCache.interpretHeader = options.interpretHeader || defaultHeaderInterpreter;
-  
+
   // CacheRequestConfig values
   axiosCache.defaults = {
     ...axios.defaults,
diff --git a/src/axios/types.ts b/src/axios/types.ts
index 53fe4732..62e64218 100644
--- a/src/axios/types.ts
+++ b/src/axios/types.ts
@@ -7,6 +7,7 @@ import type {
   Method
 } from 'axios';
 import { Deferred } from 'src/util/deferred';
+import { KeyGenerator } from 'src/util/key-generator';
 import { HeaderInterpreter } from '../header';
 import { CachedResponse, CacheStorage } from '../storage/types';
 
@@ -92,7 +93,7 @@ export default interface CacheInstance {
    * Defaults to a function that priorizes the id, and if not specified,
    * a string is generated using the method, baseUrl, params, and url
    */
-  generateKey: (options: CacheRequestConfig) => string;
+  generateKey: KeyGenerator;
 
   /**
    * A simple object that holds all deferred objects until it is resolved.
diff --git a/src/index.ts b/src/index.ts
index 673a4ce3..7a39de05 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,3 @@
 export * from './axios';
-export * as Constants from './constants';
 export * from './storage';
+export * as StatusCodes from './util/status-codes';
diff --git a/src/interceptors/request.ts b/src/interceptors/request.ts
index cb2e1303..1df321ac 100644
--- a/src/interceptors/request.ts
+++ b/src/interceptors/request.ts
@@ -1,9 +1,9 @@
 import { CachedResponse } from 'src/storage/types';
 import { AxiosCacheInstance } from '../axios/types';
-import { CACHED_RESPONSE_STATUS, CACHED_RESPONSE_STATUS_TEXT } from '../constants';
 import { Deferred } from '../util/deferred';
+import { CACHED_RESPONSE_STATUS, CACHED_RESPONSE_STATUS_TEXT } from '../util/status-codes';
 
-export function applyRequestInterceptor(axios: AxiosCacheInstance) {
+export function applyRequestInterceptor(axios: AxiosCacheInstance): void {
   axios.interceptors.request.use(async (config) => {
     // Only cache specified methods
     if (config.cache?.methods?.some((method) => (config.method || 'get').toLowerCase() == method)) {
diff --git a/src/interceptors/response.ts b/src/interceptors/response.ts
index ed6c2031..54d9b325 100644
--- a/src/interceptors/response.ts
+++ b/src/interceptors/response.ts
@@ -1,15 +1,17 @@
 import { AxiosCacheInstance } from '../axios/types';
 import { updateCache } from '../util/update-cache';
 
-export function applyResponseInterceptor(axios: AxiosCacheInstance) {
+export function applyResponseInterceptor(axios: AxiosCacheInstance): void {
   axios.interceptors.response.use(async (response) => {
     // Update other entries before updating himself
     if (response.config.cache?.update) {
       updateCache(axios, response.data, response.config.cache.update);
     }
 
+    const shouldCache = response.config.cache?.shouldCache || axios.defaults.cache.shouldCache;
+
     // Config told that this response should be cached.
-    if (!response.config.cache?.shouldCache!(response)) {
+    if (shouldCache(response)) {
       return response;
     }
 
@@ -24,14 +26,14 @@ export function applyResponseInterceptor(axios: AxiosCacheInstance) {
 
     const defaultMaxAge = response.config.cache?.maxAge || axios.defaults.cache.maxAge;
     cache.expiration = cache.expiration || defaultMaxAge;
-    let shouldCache = true;
+    let saveCache = true;
 
     if (response.config.cache?.interpretHeader) {
       const expirationTime = axios.interpretHeader(response.headers['cache-control']);
 
       // Header told that this response should not be cached.
       if (expirationTime === false) {
-        shouldCache = false;
+        saveCache = false;
       } else {
         cache.expiration = expirationTime ? expirationTime : defaultMaxAge;
       }
@@ -45,7 +47,7 @@ export function applyResponseInterceptor(axios: AxiosCacheInstance) {
       deferred.resolve(data);
     }
 
-    if (shouldCache) {
+    if (saveCache) {
       await axios.storage.set(key, {
         data,
         expiration: cache.expiration,
diff --git a/src/util/deferred.ts b/src/util/deferred.ts
index 7040b4d4..c8c3063b 100644
--- a/src/util/deferred.ts
+++ b/src/util/deferred.ts
@@ -1,9 +1,11 @@
+export type MaybePromise<T> = T | PromiseLike<T>;
+
 /**
  * Represents the completion of an asynchronous operation that can be completed later.
  */
 export class Deferred<T> {
   readonly promise: Promise<T>;
-  private _resolve: (value: T | PromiseLike<T>) => void = () => {};
+  private _resolve: (value: MaybePromise<T>) => void = () => {};
   private _reject: (reason?: any) => void = () => {};
 
   constructor() {
@@ -17,7 +19,7 @@ export class Deferred<T> {
    * Resolve this deferred promise with the given value.
    * @param the value to resolve
    */
-  public readonly resolve = (value: T | PromiseLike<T>): void => {
+  public readonly resolve = (value: MaybePromise<T>): void => {
     this._resolve(value);
   };
 
@@ -36,8 +38,8 @@ export class Deferred<T> {
    * @returns A Promise for the completion of which ever callback is executed.
    */
   public readonly then = <TResult1 = T, TResult2 = never>(
-    onfulfilled?: ((value: T) => TResult1 | PromiseLike<TResult1>) | undefined | null,
-    onrejected?: ((reason: any) => TResult2 | PromiseLike<TResult2>) | undefined | null
+    onfulfilled?: ((value: T) => MaybePromise<TResult1>) | undefined | null,
+    onrejected?: ((reason: any) => MaybePromise<TResult2>) | undefined | null
   ): Promise<TResult1 | TResult2> => {
     return this.promise.then(onfulfilled, onrejected);
   };
@@ -48,7 +50,7 @@ export class Deferred<T> {
    * @returns A Promise for the completion of the callback.
    */
   public readonly catch = <TResult = never>(
-    onrejected?: ((reason: any) => TResult | PromiseLike<TResult>) | undefined | null
+    onrejected?: ((reason: any) => MaybePromise<TResult>) | undefined | null
   ): Promise<T | TResult> => {
     return this.promise.catch(onrejected);
   };
diff --git a/src/util/interpret-header.ts b/src/util/interpret-header.ts
deleted file mode 100644
index 2873df60..00000000
--- a/src/util/interpret-header.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-import { parse } from '@tusbar/cache-control';
-import { AxiosResponse } from 'axios';
-
-// response.config.cache?.maxAge || axios.defaults.cache.maxAge
-
-/**
- * Interpret the cache control header, if present.
- *
- * @param header the header to interpret.
- * @returns false if header is not valid, undefined if the maxAge was not specified or a number in seconds from now.
- */
-export function interpretCacheHeader(
-  headers: AxiosResponse['headers']
-): false | undefined | number {
-  const cacheControl = headers['cache-control'] || '';
-  const { noCache, noStore, maxAge } = parse(cacheControl);
-
-  // Header told that this response should not be cached.
-  if (noCache || noStore) {
-    return false;
-  }
-
-  if (!maxAge) {
-    return undefined;
-  }
-
-  return Date.now() + maxAge * 1000;
-}
diff --git a/src/util/key-generator.ts b/src/util/key-generator.ts
index 853f69cb..0e6ff0c3 100644
--- a/src/util/key-generator.ts
+++ b/src/util/key-generator.ts
@@ -1,13 +1,20 @@
 import { CacheRequestConfig } from '../axios/types';
 
-export function defaultKeyGenerator({
+export type KeyGenerator = (options: CacheRequestConfig) => string;
+
+export const defaultKeyGenerator: KeyGenerator = ({
   baseURL,
   url,
-  method,
+  method: nullableMethod,
   params,
   id
-}: CacheRequestConfig): string {
-  return id
-    ? `id::${String(id)}`
-    : `${method?.toLowerCase() || 'get'}::${baseURL}::${url}::${JSON.stringify(params || '{}')}`;
-}
+}) => {
+  if (id) {
+    return `id::${String(id)}`;
+  }
+
+  const method = nullableMethod?.toLowerCase() || 'get';
+  const jsonParams = params ? JSON.stringify(params) : '{}';
+
+  return `${method}::${baseURL}::${url}::${jsonParams}`;
+};
diff --git a/src/constants.ts b/src/util/status-codes.ts
similarity index 100%
rename from src/constants.ts
rename to src/util/status-codes.ts
diff --git a/src/util/update-cache.ts b/src/util/update-cache.ts
index c89435f2..f404fd86 100644
--- a/src/util/update-cache.ts
+++ b/src/util/update-cache.ts
@@ -4,7 +4,7 @@ export async function updateCache(
   axios: AxiosCacheInstance,
   data: any,
   entries: CacheProperties['update']
-) {
+): Promise<void> {
   for (const [cacheKey, value] of Object.entries(entries)) {
     if (value == 'delete') {
       await axios.storage.remove(cacheKey);