diff --git a/README.md b/README.md
index d647992..1e2da7e 100644
--- a/README.md
+++ b/README.md
@@ -62,8 +62,12 @@ sitemapper.fetch('https://wp.seantburke.com/sitemap.xml')
 
 You can add options on the initial Sitemapper object when instantiating it.
 
-+ `requestHeaders`: (Object) - Additional Request Headers
-+ `timeout`: (Number) - Maximum timeout for a single URL
++ `requestHeaders`: (Object) - Additional Request Headers (e.g. `User-Agent`)
++ `timeout`: (Number) - Maximum timeout in ms for a single URL. Default: 15000 (15 seconds)
++ `url`: (String) - Sitemap URL to crawl
++ `debug`: (Boolean) - Enables/Disables debug console logging. Default: False
++ `concurrency`: (Number) - Sets the maximum number of concurrent sitemap crawling threads. Default: 10
++ `retries`: (Number) - Sets the maximum number of retries to attempt in case of an error response (e.g. 404 or Timeout). Default: 0
 
 ```javascript
 
@@ -77,6 +81,23 @@ const sitemapper = new Sitemapper({
 
 ```
 
+An example using all available options:
+
+```javascript
+
+const sitemapper = new Sitemapper({
+  url: 'https://art-works.community/sitemap.xml',
+  timeout: 15000,
+  requestHeaders: {
+    'User-Agent': 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:81.0) Gecko/20100101 Firefox/81.0'
+  },
+  debug: true,
+  concurrency: 2,
+  retries: 1,
+});
+
+```
+
 ### Examples in ES5
 ```javascript
 var Sitemapper = require('sitemapper');
diff --git a/lib/assets/sitemapper.js b/lib/assets/sitemapper.js
index 1b35266..27405d4 100644
--- a/lib/assets/sitemapper.js
+++ b/lib/assets/sitemapper.js
@@ -1,2 +1,2 @@
-"use strict";Object.defineProperty(exports,"__esModule",{value:!0}),exports.default=void 0;var _xml2js=require("xml2js"),_got=_interopRequireDefault(require("got")),_zlib=_interopRequireDefault(require("zlib")),_url=_interopRequireDefault(require("url")),_path=_interopRequireDefault(require("path"));function _interopRequireDefault(a){return a&&a.__esModule?a:{default:a}}function asyncGeneratorStep(a,b,c,d,e,f,g){try{var h=a[f](g),i=h.value}catch(a){return void c(a)}h.done?b(i):Promise.resolve(i).then(d,e)}function _asyncToGenerator(a){return function(){var b=this,c=arguments;return new Promise(function(d,e){function f(a){asyncGeneratorStep(h,d,e,f,g,"next",a)}function g(a){asyncGeneratorStep(h,d,e,f,g,"throw",a)}var h=a.apply(b,c);f(void 0)})}}class Sitemapper{constructor(a){var b=a||{requestHeaders:{}};this.url=b.url,this.timeout=b.timeout||15e3,this.timeoutTable={},this.requestHeaders=b.requestHeaders,this.debug=b.debug}fetch(){var a=arguments,b=this;return _asyncToGenerator(function*(){var c=0<a.length&&a[0]!==void 0?a[0]:b.url,d=[];try{d=yield b.crawl(c)}catch(a){b.debug&&console.error(a)}return{url:c,sites:d}})()}static get timeout(){return this.timeout}static set timeout(a){this.timeout=a}static set url(a){this.url=a}static get url(){return this.url}static set debug(a){this.debug=a}static get debug(){return this.debug}parse(){var a=arguments,b=this;return _asyncToGenerator(function*(){var c=0<a.length&&a[0]!==void 0?a[0]:b.url,d={method:"GET",resolveWithFullResponse:!0,gzip:!0,responseType:"buffer",headers:b.requestHeaders};try{var e=(0,_got.default)(c,d);b.initializeTimeout(c,e);var f=yield e;if(!f||200!==f.statusCode)return clearTimeout(b.timeoutTable[c]),{error:f.error,data:f};var g=b.isGzip(c)?yield b.decompressResponseBody(f.body):f.body;var h=yield(0,_xml2js.parseStringPromise)(g);return{error:null,data:h}}catch(a){return"CancelError"===a.name?{error:"Request timed out after ".concat(b.timeout," milliseconds for url: '").concat(c,"'"),data:a}:{error:a.error,data:a}}})()}initializeTimeout(a,b){this.timeoutTable[a]=setTimeout(()=>b.cancel(),this.timeout)}crawl(a){var b=this;return _asyncToGenerator(function*(){try{var{error:g,data:h}=yield b.parse(a);if(clearTimeout(b.timeoutTable[a]),g)return b.debug&&console.error("Error occurred during \"crawl('".concat(a,"')\":\n\r Error: ").concat(g)),[];if(h&&h.urlset&&h.urlset.url){b.debug&&console.debug("Urlset found during \"crawl('".concat(a,"')\""));var i=h.urlset.url.map(a=>a.loc&&a.loc[0]);return[].concat(i)}if(h&&h.sitemapindex){b.debug&&console.debug("Additional sitemap found during \"crawl('".concat(a,"')\""));var c=h.sitemapindex.sitemap.map(a=>a.loc&&a.loc[0]),d=c.map(a=>b.crawl(a)),e=yield Promise.all(d),f=e.filter(a=>!a.error).reduce((a,b)=>a.concat(b),[]);return f}return b.debug&&console.error("Unknown state during \"crawl('".concat(a,")'\":"),g,h),[]}catch(a){b.debug&&b.debug&&console.error(a)}})()}getSites(){var a=arguments,b=this;return _asyncToGenerator(function*(){var c=0<a.length&&a[0]!==void 0?a[0]:b.url,d=1<a.length?a[1]:void 0;console.warn("\r\nWarning:","function .getSites() is deprecated, please use the function .fetch()\r\n");var e={},f=[];try{var g=yield b.fetch(c);f=g.sites}catch(a){e=a}return d(e,f)})()}isGzip(a){var b=_url.default.parse(a),c=_path.default.extname(b.path);return".gz"===c}decompressResponseBody(a){return new Promise((b,c)=>{var d=Buffer.from(a);_zlib.default.gunzip(d,(a,d)=>{a?c(a):b(d)})})}}exports.default=Sitemapper,module.exports=exports.default,module.exports.default=exports.default;
+"use strict";Object.defineProperty(exports,"__esModule",{value:!0}),exports.default=void 0;var _xml2js=require("xml2js"),_got=_interopRequireDefault(require("got")),_zlib=_interopRequireDefault(require("zlib")),_url=_interopRequireDefault(require("url")),_path=_interopRequireDefault(require("path")),_pLimit=_interopRequireDefault(require("p-limit"));function _interopRequireDefault(a){return a&&a.__esModule?a:{default:a}}function asyncGeneratorStep(a,b,c,d,e,f,g){try{var h=a[f](g),i=h.value}catch(a){return void c(a)}h.done?b(i):Promise.resolve(i).then(d,e)}function _asyncToGenerator(a){return function(){var b=this,c=arguments;return new Promise(function(d,e){function f(a){asyncGeneratorStep(h,d,e,f,g,"next",a)}function g(a){asyncGeneratorStep(h,d,e,f,g,"throw",a)}var h=a.apply(b,c);f(void 0)})}}class Sitemapper{constructor(a){var b=a||{requestHeaders:{}};this.url=b.url,this.timeout=b.timeout||15e3,this.timeoutTable={},this.requestHeaders=b.requestHeaders,this.debug=b.debug,this.concurrency=b.concurrency||10,this.retries=b.retries||0}fetch(){var a=arguments,b=this;return _asyncToGenerator(function*(){var c=0<a.length&&a[0]!==void 0?a[0]:b.url,d={url:"",sites:[],errors:[]};try{d=yield b.crawl(c)}catch(a){b.debug&&console.error(a)}return{url:c,sites:d.sites||[],errors:d.errors||[]}})()}static get timeout(){return this.timeout}static set timeout(a){this.timeout=a}static set url(a){this.url=a}static get url(){return this.url}static set debug(a){this.debug=a}static get debug(){return this.debug}parse(){var a=arguments,b=this;return _asyncToGenerator(function*(){var c=0<a.length&&a[0]!==void 0?a[0]:b.url,d={method:"GET",resolveWithFullResponse:!0,gzip:!0,responseType:"buffer",headers:b.requestHeaders};try{var e=(0,_got.default)(c,d);b.initializeTimeout(c,e);var f=yield e;if(!f||200!==f.statusCode)return clearTimeout(b.timeoutTable[c]),{error:f.error,data:f};var g=b.isGzip(c)?yield b.decompressResponseBody(f.body):f.body;var h=yield(0,_xml2js.parseStringPromise)(g);return{error:null,data:h}}catch(a){return"CancelError"===a.name?{error:"Request timed out after ".concat(b.timeout," milliseconds for url: '").concat(c,"'"),data:a}:{error:"Error occurred: ".concat(a.name),data:a}}})()}initializeTimeout(a,b){this.timeoutTable[a]=setTimeout(()=>b.cancel(),this.timeout)}crawl(a){var b=arguments,c=this;return _asyncToGenerator(function*(){var d=1<b.length&&b[1]!==void 0?b[1]:0;try{var{error:k,data:l}=yield c.parse(a);if(clearTimeout(c.timeoutTable[a]),k)return d<c.retries?(c.debug&&console.log("(Retry attempt: ".concat(d+1," / ").concat(c.retries,") ").concat(a," due to ").concat(l.name," on previous request")),c.crawl(a,d+1)):(c.debug&&console.error("Error occurred during \"crawl('".concat(a,"')\":\n\r Error: ").concat(k)),{sites:[],errors:[{type:l.name,url:a,retries:d}]});if(l&&l.urlset&&l.urlset.url){c.debug&&console.debug("Urlset found during \"crawl('".concat(a,"')\""));var m=l.urlset.url.map(a=>a.loc&&a.loc[0]);return{sites:m,errors:[]}}if(l&&l.sitemapindex){c.debug&&console.debug("Additional sitemap found during \"crawl('".concat(a,"')\""));var e=l.sitemapindex.sitemap.map(a=>a.loc&&a.loc[0]),f=(0,_pLimit.default)(c.concurrency),g=e.map(a=>f(()=>c.crawl(a))),h=yield Promise.all(g),i=h.filter(a=>0===a.errors.length).reduce((a,b)=>{var{sites:c}=b;return[...a,...c]},[]),j=h.filter(a=>0!==a.errors.length).reduce((a,b)=>{var{errors:c}=b;return[...a,...c]},[]);return{sites:i,errors:j}}return d<c.retries?(c.debug&&console.log("(Retry attempt: ".concat(d+1," / ").concat(c.retries,") ").concat(a," due to ").concat(l.name," on previous request")),c.crawl(a,d+1)):(c.debug&&console.error("Unknown state during \"crawl('".concat(a,")'\":"),k,l),{sites:[],errors:[{url:a,type:l.name||"UnknownStateError",retries:d}]})}catch(a){c.debug&&c.debug&&console.error(a)}})()}getSites(){var a=arguments,b=this;return _asyncToGenerator(function*(){var c=0<a.length&&a[0]!==void 0?a[0]:b.url,d=1<a.length?a[1]:void 0;console.warn("\r\nWarning:","function .getSites() is deprecated, please use the function .fetch()\r\n");var e={},f=[];try{var g=yield b.fetch(c);f=g.sites}catch(a){e=a}return d(e,f)})()}isGzip(a){var b=_url.default.parse(a),c=_path.default.extname(b.path);return".gz"===c}decompressResponseBody(a){return new Promise((b,c)=>{var d=Buffer.from(a);_zlib.default.gunzip(d,(a,d)=>{a?c(a):b(d)})})}}exports.default=Sitemapper,module.exports=exports.default,module.exports.default=exports.default;
 //# sourceMappingURL=sitemapper.js.map
\ No newline at end of file
diff --git a/lib/examples/index.js b/lib/examples/index.js
index 4d45219..64b6198 100644
--- a/lib/examples/index.js
+++ b/lib/examples/index.js
@@ -1,2 +1,2 @@
-"use strict";var _sitemapper=_interopRequireDefault(require("../assets/sitemapper"));function _interopRequireDefault(a){return a&&a.__esModule?a:{default:a}}function asyncGeneratorStep(a,b,c,d,e,f,g){try{var h=a[f](g),i=h.value}catch(a){return void c(a)}h.done?b(i):Promise.resolve(i).then(d,e)}function _asyncToGenerator(a){return function(){var b=this,c=arguments;return new Promise(function(d,e){function f(a){asyncGeneratorStep(h,d,e,f,g,"next",a)}function g(a){asyncGeneratorStep(h,d,e,f,g,"throw",a)}var h=a.apply(b,c);f(void 0)})}}var exampleURL="https://www.walmart.com/sitemap_topic.xml",sitemapper=new _sitemapper.default({url:"https://www.walmart.com/sitemap_topic.xml",debug:!0,timeout:1});_asyncToGenerator(function*(){try{var a=yield sitemapper.fetch();console.log(a)}catch(a){console.error(a)}})();
+"use strict";var _sitemapper=_interopRequireDefault(require("../assets/sitemapper"));function _interopRequireDefault(a){return a&&a.__esModule?a:{default:a}}function asyncGeneratorStep(a,b,c,d,e,f,g){try{var h=a[f](g),i=h.value}catch(a){return void c(a)}h.done?b(i):Promise.resolve(i).then(d,e)}function _asyncToGenerator(a){return function(){var b=this,c=arguments;return new Promise(function(d,e){function f(a){asyncGeneratorStep(h,d,e,f,g,"next",a)}function g(a){asyncGeneratorStep(h,d,e,f,g,"throw",a)}var h=a.apply(b,c);f(void 0)})}}var exampleURL="https://www.walmart.com/sitemap_topic.xml",sitemapper=new _sitemapper.default({url:"https://www.walmart.com/sitemap_topic.xml",debug:!1,timeout:1e4,concurrency:10,retries:0});_asyncToGenerator(function*(){try{var a=yield sitemapper.fetch();console.log(a)}catch(a){console.error(a)}})();
 //# sourceMappingURL=index.js.map
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
index 47cde49..cbbb50f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "sitemapper",
-  "version": "3.1.16",
+  "version": "3.2.0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -3482,6 +3482,17 @@
           "dev": true,
           "requires": {
             "p-limit": "^2.0.0"
+          },
+          "dependencies": {
+            "p-limit": {
+              "version": "2.3.0",
+              "resolved": "https://registry.npmjs.org/p-limit/-/p-limit-2.3.0.tgz",
+              "integrity": "sha512-//88mFWSJx8lxCzwdAABTJL2MyWB12+eIY7MDL2SqLmAkeKU9qxRvWuSyTjm3FUmpBEMuFfckAIqEaVGUDxb6w==",
+              "dev": true,
+              "requires": {
+                "p-try": "^2.0.0"
+              }
+            }
           }
         },
         "path-exists": {
@@ -6342,12 +6353,11 @@
       "integrity": "sha512-wvPXDmbMmu2ksjkB4Z3nZWTSkJEb9lqVdMaCKpZUGJG9TMiNp9XcbG3fn9fPKjem04fJMJnXoyFPk2FmgiaiNg=="
     },
     "p-limit": {
-      "version": "2.3.0",
-      "resolved": "https://registry.npmjs.org/p-limit/-/p-limit-2.3.0.tgz",
-      "integrity": "sha512-//88mFWSJx8lxCzwdAABTJL2MyWB12+eIY7MDL2SqLmAkeKU9qxRvWuSyTjm3FUmpBEMuFfckAIqEaVGUDxb6w==",
-      "dev": true,
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/p-limit/-/p-limit-3.1.0.tgz",
+      "integrity": "sha512-TYOanM3wGwNGsZN2cVTYPArw454xnXj5qmWF1bEoAc4+cU/ol7GVh7odevjp1FNHduHc3KZMcFduxU5Xc6uJRQ==",
       "requires": {
-        "p-try": "^2.0.0"
+        "yocto-queue": "^0.1.0"
       }
     },
     "p-locate": {
@@ -6357,6 +6367,17 @@
       "dev": true,
       "requires": {
         "p-limit": "^2.2.0"
+      },
+      "dependencies": {
+        "p-limit": {
+          "version": "2.3.0",
+          "resolved": "https://registry.npmjs.org/p-limit/-/p-limit-2.3.0.tgz",
+          "integrity": "sha512-//88mFWSJx8lxCzwdAABTJL2MyWB12+eIY7MDL2SqLmAkeKU9qxRvWuSyTjm3FUmpBEMuFfckAIqEaVGUDxb6w==",
+          "dev": true,
+          "requires": {
+            "p-try": "^2.0.0"
+          }
+        }
       }
     },
     "p-try": {
@@ -6775,6 +6796,17 @@
           "dev": true,
           "requires": {
             "p-limit": "^2.0.0"
+          },
+          "dependencies": {
+            "p-limit": {
+              "version": "2.3.0",
+              "resolved": "https://registry.npmjs.org/p-limit/-/p-limit-2.3.0.tgz",
+              "integrity": "sha512-//88mFWSJx8lxCzwdAABTJL2MyWB12+eIY7MDL2SqLmAkeKU9qxRvWuSyTjm3FUmpBEMuFfckAIqEaVGUDxb6w==",
+              "dev": true,
+              "requires": {
+                "p-try": "^2.0.0"
+              }
+            }
           }
         },
         "path-exists": {
@@ -8710,8 +8742,7 @@
     "yocto-queue": {
       "version": "0.1.0",
       "resolved": "https://registry.npmjs.org/yocto-queue/-/yocto-queue-0.1.0.tgz",
-      "integrity": "sha512-rVksvsnNCdJ/ohGc6xgPwyN8eheCxsiLM8mxuE/t/mOVqJewPuO1miLpTHQiRgTKCLexL4MeAFVagts7HmNZ2Q==",
-      "dev": true
+      "integrity": "sha512-rVksvsnNCdJ/ohGc6xgPwyN8eheCxsiLM8mxuE/t/mOVqJewPuO1miLpTHQiRgTKCLexL4MeAFVagts7HmNZ2Q=="
     }
   }
 }
diff --git a/package.json b/package.json
index 4695ac8..dade74d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "sitemapper",
-  "version": "3.1.16",
+  "version": "3.2.0",
   "description": "Parser for XML Sitemaps to be used with Robots.txt and web crawlers",
   "keywords": [
     "parse",
@@ -78,6 +78,7 @@
   },
   "dependencies": {
     "got": "^11.8.0",
+    "p-limit": "^3.1.0",
     "xml2js": "^0.4.23"
   }
 }
diff --git a/sitemapper.d.ts b/sitemapper.d.ts
index df7b328..b0be714 100644
--- a/sitemapper.d.ts
+++ b/sitemapper.d.ts
@@ -1,26 +1,36 @@
 export interface SitemapperResponse {
-    url: string;
-    sites: string[];
+  url: string;
+  sites: string[];
+  errors: SitemapperErrorData[];
+}
+
+export interface SitemapperErrorData {
+  type: string;
+  url: string;
+  retries: number;
 }
 
 export interface SitemapperOptions {
-    url?: string;
-    timeout?: number;
-    requestHeaders?: {[name: string]: string};
+  url?: string;
+  timeout?: number;
+  requestHeaders?: {[name: string]: string};
+  debug?: boolean;
+  concurrency?: number;
+  retries?: number;
 }
 
 declare class Sitemapper {
 
-    timeout: number;
+  timeout: number;
 
-    constructor(options: SitemapperOptions)
+  constructor(options: SitemapperOptions)
 
-    /**
-     * Gets the sites from a sitemap.xml with a given URL
-     * 
-     * @param url URL to the sitemap.xml file
-     */
-    fetch(url?: string): Promise<SitemapperResponse>;
+  /**
+   * Gets the sites from a sitemap.xml with a given URL
+   *
+   * @param url URL to the sitemap.xml file
+   */
+  fetch(url?: string): Promise<SitemapperResponse>;
 }
 
 export default Sitemapper;
diff --git a/src/assets/sitemapper.js b/src/assets/sitemapper.js
index b149854..caa7b6a 100644
--- a/src/assets/sitemapper.js
+++ b/src/assets/sitemapper.js
@@ -11,6 +11,7 @@ import got from 'got';
 import zlib from 'zlib';
 import Url from 'url';
 import path from 'path';
+import pLimit from 'p-limit';
 
 /**
  * @typedef {Object} Sitemapper
@@ -22,6 +23,9 @@ export default class Sitemapper {
    * @params {Object} options to set
    * @params {string} [options.url] - the Sitemap url (e.g https://wp.seantburke.com/sitemap.xml)
    * @params {Timeout} [options.timeout] - @see {timeout}
+   * @params {boolean} [options.debug] - Enables/Disables additional logging
+   * @params {integer} [options.concurrency] - The number of concurrent sitemaps to crawl (e.g. 2 will crawl no more than 2 sitemaps at the same time)
+   * @params {integer} [options.retries] - The maximum number of retries to attempt when crawling fails (e.g. 1 for 1 retry, 2 attempts in total)
    *
    * @example let sitemap = new Sitemapper({
    *   url: 'https://wp.seantburke.com/sitemap.xml',
@@ -35,6 +39,8 @@ export default class Sitemapper {
     this.timeoutTable = {};
     this.requestHeaders = settings.requestHeaders;
     this.debug = settings.debug;
+    this.concurrency = settings.concurrency || 10;
+    this.retries = settings.retries || 0;
   }
 
   /**
@@ -47,23 +53,31 @@ export default class Sitemapper {
    *  .then((sites) => console.log(sites));
    */
   async fetch(url = this.url) {
-    let sites = [];
+    // initialize empty variables
+    let results = {
+      url: '',
+      sites: [],
+      errors: [],
+    };
+
+    // attempt to set the variables with the crawl
     try {
       // crawl the URL
-      sites = await this.crawl(url);
+      results = await this.crawl(url);
     } catch (e) {
+      // show errors that may occur
       if (this.debug) {
         console.error(e);
       }
     }
 
-    // If we run into an error, don't throw, but instead return an empty array
     return {
       url,
-      sites,
+      sites: results.sites || [],
+      errors: results.errors || [],
     };
-  }
 
+  }
   /**
    * Get the timeout
    *
@@ -178,7 +192,7 @@ export default class Sitemapper {
 
       // Otherwise notify of another error
       return {
-        error: error.error,
+        error: `Error occurred: ${error.name}`,
         data: error
       };
     }
@@ -203,49 +217,98 @@ export default class Sitemapper {
    * @private
    * @recursive
    * @param {string} url - the Sitemaps url (e.g https://wp.seantburke.com/sitemap.xml)
-   * @returns {Promise<SitesArray> | Promise<ParseData>}
+   * @param {integer} retryIndex - Number of retry attempts fro this URL (e.g. 0 for 1st attempt, 1 for second attempty etc.)
+   * @returns {Promise<SitesData>}
    */
-  async crawl(url) {
+  async crawl(url, retryIndex = 0) {
     try {
       const { error, data } = await this.parse(url);
       // The promise resolved, remove the timeout
       clearTimeout(this.timeoutTable[url]);
 
       if (error) {
+        // Handle errors during sitemap parsing / request
+        // Retry on error until you reach the retry limit set in the settings
+        if (retryIndex < this.retries) {
+          if (this.debug) {
+            console.log (`(Retry attempt: ${retryIndex + 1} / ${this.retries}) ${url} due to ${data.name} on previous request`);
+          }
+          return this.crawl(url, retryIndex + 1);
+        }
+
         if (this.debug) {
           console.error(`Error occurred during "crawl('${url}')":\n\r Error: ${error}`);
         }
-        // Fail silently
-        return [];
+
+        // Fail and log error
+        return {
+          sites: [],
+          errors: [{
+            type: data.name,
+            url,
+            retries: retryIndex,
+          }]
+        };
+
       } else if (data && data.urlset && data.urlset.url) {
+        // Handle URLs found inside the sitemap
         if (this.debug) {
           console.debug(`Urlset found during "crawl('${url}')"`);
         }
         const sites = data.urlset.url.map(site => site.loc && site.loc[0]);
-        return [].concat(sites);
+        return {
+          sites,
+          errors: []
+        }
+
       } else if (data && data.sitemapindex) {
+        // Handle child sitemaps found inside the active sitemap
         if (this.debug) {
           console.debug(`Additional sitemap found during "crawl('${url}')"`);
         }
         // Map each child url into a promise to create an array of promises
         const sitemap = data.sitemapindex.sitemap.map(map => map.loc && map.loc[0]);
-        const promiseArray = sitemap.map(site => this.crawl(site));
+
+        // Parse all child urls within the concurrency limit in the settings
+        const limit = pLimit(this.concurrency);
+        const promiseArray = sitemap.map(site => limit(() => this.crawl(site)));
 
         // Make sure all the promises resolve then filter and reduce the array
         const results = await Promise.all(promiseArray);
         const sites = results
-          .filter(result => !result.error)
-          .reduce((prev, curr) => prev.concat(curr), []);
+          .filter(result => (result.errors.length === 0))
+          .reduce((prev, { sites }) => [...prev, ...sites], []);
+        const errors = results
+          .filter(result => (result.errors.length !== 0))
+          .reduce((prev, { errors }) => [...prev, ...errors], []);
 
-        return sites;
+        return {
+          sites,
+          errors,
+        };
       }
 
+      // Retry on error until you reach the retry limit set in the settings
+      if (retryIndex < this.retries) {
+        if (this.debug) {
+          console.log (`(Retry attempt: ${retryIndex + 1} / ${this.retries}) ${url} due to ${data.name} on previous request`);
+        }
+        return this.crawl(url, retryIndex + 1);
+      }
       if (this.debug) {
         console.error(`Unknown state during "crawl('${url})'":`, error, data);
       }
 
-      // Fail silently
-      return [];
+      // Fail and log error
+      return {
+        sites: [],
+        errors: [{
+          url,
+          type: data.name || 'UnknownStateError',
+          retries: retryIndex
+        }]
+      };
+
     } catch (e) {
       if (this.debug) {
         this.debug && console.error(e);
@@ -340,7 +403,7 @@ export default class Sitemapper {
  * @property {Object} data.sitemapindex - index of sitemap
  * @property {string} data.sitemapindex.sitemap - Sitemap
  * @example {
- *   error: "There was an error!"
+ *   error: 'There was an error!'
  *   data: {
  *     url: 'https://linkedin.com',
  *     urlset: [{
@@ -359,11 +422,24 @@ export default class Sitemapper {
  *
  * @property {string} url - the original url used to query the data
  * @property {SitesArray} sites
+ * @property {ErrorDataArray} errors
  * @example {
  *   url: 'https://linkedin.com/sitemap.xml',
  *   sites: [
  *     'https://linkedin.com/project1',
  *     'https://linkedin.com/project2'
+ *   ],
+ *   errors: [
+ *      {
+ *        type: 'CancelError',
+ *        url: 'https://www.walmart.com/sitemap_tp1.xml',
+ *        retries: 0
+ *      },
+ *      {
+ *        type: 'HTTPError',
+ *        url: 'https://www.walmart.com/sitemap_tp2.xml',
+ *        retries: 0
+ *      },
  *   ]
  * }
  */
@@ -377,3 +453,36 @@ export default class Sitemapper {
  *   'https://www.linkedin.com'
  * ]
  */
+
+/**
+ * An array of Error data objects
+ *
+ * @typedef {ErrorData[]} ErrorDataArray
+ * @example [
+ *    {
+ *      type: 'CancelError',
+ *      url: 'https://www.walmart.com/sitemap_tp1.xml',
+ *      retries: 0
+ *    },
+ *    {
+ *      type: 'HTTPError',
+ *      url: 'https://www.walmart.com/sitemap_tp2.xml',
+ *      retries: 0
+ *    },
+ * ]
+ */
+
+/**
+ * An object containing details about the errors which occurred during the crawl
+ *
+ * @typedef {Object} ErrorData
+ *
+ * @property {string} type - The error type which was returned
+ * @property {string} url - The sitemap URL which returned the error
+ * @property {Number} errors - The total number of retries attempted after receiving the first error
+ * @example {
+ *    type: 'CancelError',
+ *    url: 'https://www.walmart.com/sitemap_tp1.xml',
+ *    retries: 0
+ * }
+ */
diff --git a/src/examples/index.js b/src/examples/index.js
index c868d54..3cabd7b 100644
--- a/src/examples/index.js
+++ b/src/examples/index.js
@@ -6,8 +6,10 @@ const exampleURL = 'https://www.walmart.com/sitemap_topic.xml';
 // Instantiate an instance
 const sitemapper = new Sitemapper({
   url: exampleURL, // url to crawl
-  debug: true, // don't show debug logs
-  timeout: 1, // 10 seconds
+  debug: false, // don't show debug logs
+  timeout: 10000, // 10 seconds
+  concurrency: 10, // Number of maximum concurrent sitemap crawl threads
+  retries: 0, // Number of retry attempts in case of error response (e.g. 404 or timeout)
 });
 
 /**
diff --git a/src/tests/test.es5.js b/src/tests/test.es5.js
index 8180954..e5e535b 100644
--- a/src/tests/test.es5.js
+++ b/src/tests/test.es5.js
@@ -79,6 +79,7 @@ describe('Sitemapper', function () {
       sitemapper.fetch(url)
         .then(data => {
           data.sites.should.be.Array;
+          data.errors.should.be.Array;
           done();
         })
         .catch(error => {
@@ -138,6 +139,33 @@ describe('Sitemapper', function () {
     });
   });
 
+  describe('gzipped sitemaps', function () {
+    beforeEach(() => {
+      sitemapper = new Sitemapper({
+        requestHeaders: {
+          'Accept-Encoding': 'gzip,deflate,sdch',
+        }
+      });
+    });
+
+    it('https://www.banggood.com/sitemap/category.xml.gz gzip should be a non-empty array', function (done) {
+      this.timeout(30000);
+      const url = 'https://www.banggood.com/sitemap/category.xml.gz';
+      sitemapper.timeout = 10000;
+      sitemapper.fetch(url)
+        .then(data => {
+          data.sites.should.be.Array;
+          data.errors.should.be.Array;
+          data.sites.length.should.be.greaterThan(0);
+          done();
+        })
+        .catch(error => {
+          console.error('Test failed');
+          done(error);
+        });
+    });
+  });
+
   describe('getSites method', function () {
     it('getSites should be backwards compatible', function (done) {
       this.timeout(30000);
diff --git a/src/tests/test.js b/src/tests/test.js
index d48943f..81d4706 100644
--- a/src/tests/test.js
+++ b/src/tests/test.js
@@ -77,9 +77,14 @@ describe('Sitemapper', function () {
     it('gibberish.gibberish should fail silently with an empty array', function (done) {
       this.timeout(30000);
       const url = 'http://gibberish.gibberish';
+      sitemapper.debug = true;
       sitemapper.fetch(url)
         .then(data => {
           data.sites.should.be.Array;
+          data.errors.should.be.Array;
+          data.errors.length.should.be.greaterThan(0);
+          data.errors.length.should.be.greaterThan(0);
+          console.log(data);
           done();
         })
         .catch(error => {
@@ -130,6 +135,8 @@ describe('Sitemapper', function () {
       sitemapper.fetch(url)
         .then(data => {
           data.sites.should.be.Array;
+          data.errors.should.be.Array;
+          console.log(data);
           done();
         })
         .catch(error => {
@@ -138,9 +145,25 @@ describe('Sitemapper', function () {
         });
     });
 
-    it('https://m.banggood.com/sitemap/category.xml.gz gzip should be a non-empty array', function (done) {
+    it('https://www.golinks.com/blog/sitemap.xml sitemaps should return an empty array when timing out', function (done) {
       this.timeout(30000);
-      const url = 'https://m.banggood.com/sitemap/category.xml.gz';
+      const url = 'https://www.golinks.com/blog/sitemap.xml';
+      sitemapper.timeout = 10000;
+      sitemapper.fetch(url)
+        .then(data => {
+          data.sites.should.be.Array;
+          data.errors.should.be.Array;
+          done();
+        })
+        .catch(error => {
+          console.error('Test failed');
+          done(error);
+        });
+    });
+
+    it('https://www.banggood.com/sitemap/category.xml.gz gzip should be a non-empty array', function (done) {
+      this.timeout(30000);
+      const url = 'https://www.banggood.com/sitemap/category.xml.gz';
       sitemapper.timeout = 10000;
       sitemapper.fetch(url)
         .then(data => {
@@ -164,13 +187,14 @@ describe('Sitemapper', function () {
       });
     });
 
-    it('https://m.banggood.com/sitemap/category.xml.gz gzip should be a non-empty array', function (done) {
+    it('https://www.banggood.com/sitemap/category.xml.gz gzip should be a non-empty array', function (done) {
       this.timeout(30000);
-      const url = 'https://m.banggood.com/sitemap/category.xml.gz';
+      const url = 'https://www.banggood.com/sitemap/category.xml.gz';
       sitemapper.timeout = 10000;
       sitemapper.fetch(url)
         .then(data => {
           data.sites.should.be.Array;
+          data.errors.should.be.Array;
           data.sites.length.should.be.greaterThan(0);
           done();
         })
diff --git a/src/tests/test.ts.ts b/src/tests/test.ts.ts
index 488a430..ee0576c 100644
--- a/src/tests/test.ts.ts
+++ b/src/tests/test.ts.ts
@@ -81,6 +81,7 @@ describe('Sitemapper', function () {
       sitemapper.fetch(url)
         .then(data => {
           data.sites.should.be.Array;
+          data.errors.should.be.Array;
           done();
         })
         .catch(error => {
@@ -141,6 +142,33 @@ describe('Sitemapper', function () {
     });
   });
 
+  describe('gzipped sitemaps', function () {
+    beforeEach(() => {
+      sitemapper = new Sitemapper({
+        requestHeaders: {
+          'Accept-Encoding': 'gzip,deflate,sdch',
+        }
+      });
+    });
+
+    it('https://www.banggood.com/sitemap/category.xml.gz gzip should be a non-empty array', function (done) {
+      this.timeout(30000);
+      const url = 'https://www.banggood.com/sitemap/category.xml.gz';
+      sitemapper.timeout = 10000;
+      sitemapper.fetch(url)
+        .then(data => {
+          data.sites.should.be.Array;
+          data.errors.should.be.Array;
+          data.sites.length.should.be.greaterThan(0);
+          done();
+        })
+        .catch(error => {
+          console.error('Test failed');
+          done(error);
+        });
+    });
+  });
+
   describe('getSites method', function () {
     it('getSites should be backwards compatible', function (done) {
       this.timeout(30000);