The Front-End Checklist is an exhaustive list of all elements you need to have / to test before launching your site / HTML page to production.
It is based on Front-End developers' years of experience, with the additions coming from some other open-source checklists.
Table of Contents
How to use?
All items in the Front-End Checklist are required for the majority of the projects, but some elements can be omitted or are not essential (in the case of an administration web app, you may not need RSS feed for example). We choose to use 3 levels of flexibility:
- means that the item is recommended but can be omitted in some particular situations.
- means that the item is highly recommended and can eventually be omitted in some really particular cases. Some elements, if omitted, can have bad repercussions in terms of performance or SEO.
- means that the item can't be omitted by any reason. You may cause a dysfunction in your page or have accessibility or SEO issues. The testing priority needs to be on these elements first.
Some resources possess an emoticon to help you understand which type of content / help you may find on the checklist:
📖: documentation or article 🛠: online tool / testing tool 📹: media or video content
Notes: You can find a list of everything that could be found in the
<head>of an HTML document.
<!-- Doctype HTML5 --> <!doctype html>
The next 3 meta tags (Charset, X-UA Compatible and Viewport) need to come first in the head.
<!-- Set character encoding for the document --> <meta charset="utf-8">
<!-- Instruct Internet Explorer to use its latest rendering engine --> <meta http-equiv="x-ua-compatible" content="ie=edge">
<!-- Viewport for responsive web design --> <meta name="viewport" content="width=device-width, initial-scale=1">
- Title: A title is used on all pages (SEO: Google calculate the pixel width of the characters used in the title, cut off between 472 and 482 pixels. Average character limit would be around 55-characters).
<!-- Document Title --> <title>Page Title less than 65 characters</title>
- Description: A meta description is provided, it is unique and doesn't possess more than 150 characters.
<!-- Meta Description --> <meta name="description" content="Description of the page less than 150 characters">
- Favicons: Each favicon has been created and displays correctly. If you have only a
favicon.ico, put it at the root of your site. Normally you won't need to use any markup. However, it's still good practice to link to it using the example below. Today, PNG format is recommended over
.icoformat (dimensions: 32x32px).
<!-- Standard favicon --> <link rel="icon" type="image/x-icon" href="https://example.com/favicon.ico"> <!-- Recommended favicon format --> <link rel="icon" type="image/png" href="https://example.com/favicon.png">
- Apple Touch Icon: Apple touch favicon apple-mobile-web-app-capable are present. (Create your Apple Icon file with at least 200x200px dimension to support all dimensions that you may need)
<!-- Apple Touch Icon --> <link rel="apple-touch-icon" href="/custom-icon.png">
<!-- Microsoft Tiles --> <meta name="msapplication-config" content="browserconfig.xml" />
Minimum required xml markup for the browserconfig.xml file is as follows:
<?xml version="1.0" encoding="utf-8"?> <browserconfig> <msapplication> <tile> <square70x70logo src="small.png"/> <square150x150logo src="medium.png"/> <wide310x150logo src="wide.png"/> <square310x310logo src="large.png"/> </tile> </msapplication> </browserconfig>
<!-- Helps prevent duplicate content issues --> <link rel="canonical" href="http://example.com/2017/09/a-new-article-to-red.html">
- Language attribute: The
langattribute of your website is specified and related to the language of the current page.
- Direction attribute: The direction of lecture is specified on the html tag (It can be used on another HTML tag).
- Alternate language: The language tag of your website is specified and related to the language of the current page.
<link rel="alternate" href="https://es.example.com/" hreflang="es">
inline critical CSS: CSS which styles content that is immediately visible during pageload ("above the fold content") is called "critical CSS". It is embedded before your principal CSS call and between
<style></style>in a single line (minified).
🛠Critical by Addy Osmani on Github automates this
<head>. (Except the case where sometimes JS files are loaded asynchronously on top of your page).
Facebook OG and Twitter Cards are, for any website, highly recommended. The other social media tags can be considered if you target a particular presence on those and want to ensure the display.
- Facebook Open Graph: All Facebook Open Graph (OG) are tested and no one is missing or with a false information. Images need to be at least 600 x 315 pixels, 1200 x 630 pixels recommended.
Notes: Using use og:image:width and og:image:height will specify the image dimensions to the crawler so that it can render the image immediately without having to asynchronously download and process it.
<meta property="og:type" content="website"> <meta property="og:url" content="https://example.com/page.html"> <meta property="og:title" content="Content Title"> <meta property="og:image" content="https://example.com/image.jpg"> <meta property="og:description" content="Description Here"> <meta property="og:site_name" content="Site Name"> <meta property="og:locale" content="en_US"> <!-- Next tags are optional but recommended --> <meta property="og:image:width" content="1200"> <meta property="og:image:height" content="630">
<meta name="twitter:card" content="summary"> <meta name="twitter:site" content="@site_account"> <meta name="twitter:creator" content="@individual_account"> <meta name="twitter:url" content="https://example.com/page.html"> <meta name="twitter:title" content="Content Title"> <meta name="twitter:description" content="Content description less than 200 characters"> <meta name="twitter:image" content="https://example.com/image.jpg">
- HTML5 Semantic Elements: HTML5 Semantic Elements are used appropriately (header, section, footer, main...).
Noopener: In case you are using external links with
target="_blank", your link should have a
rel="noopener"attribute to prevent tab nabbing. If you need to support older versions of Firefox, use
- W3C compliant: All pages need to be tested with the W3C validator to identify possible issues in the HTML code.
- Adblockers test: Your website shows your content correctly with adblockers enabled (You can provide a message encouraging people to disable their adblocker).
Notes: Using webfonts may cause Flash Of Unstyled Text/Flash Of Invisible Text - consider having fallback fonts and/or utilizing webfont loaders to control behavior.
Notes: Take a look at CSS guidelines and Sass Guidelines followed by most Front-End developers. If you have a doubt about CSS properties, you can visit CSS Reference. There is also a short Code Guide for consistency
- Responsive Web Design: The website is using responsive web design.
- CSS Print: A print stylesheet is provided and is correct on each page.
- Preprocessors: Your page is using a CSS preprocessor (Sass is preferred).
- Unique ID: If IDs are used, they are unique to a page.
- Reset CSS: A CSS reset (reset, normalize or reboot) is used and up to date. (If you are using a CSS Framework like Bootstrap or Foundation, a Normalize is already included into it.)
<div id="js-slider" class="my-slider"> <!-- Or --> <div id="id-used-by-cms" class="js-slider my-slider">
- Embedded or inline CSS: Avoid at all cost embeding CSS in
<style>tags or using inline CSS: only use for valid reasons (e.g. background-image for slider, critical CSS).
- Vendor prefixes: CSS vendor prefixes are used and are generated accordingly with your browser support compatibility.
- Concatenation: CSS files are concatenated in a single file. (Not for HTTP/2)
- Minification: All CSS files are minified.
- Non-blocking: CSS files need to be non-blocking to prevent the DOM from taking time to load.
- Desktop Browsers: All pages were tested on all current desktop browsers (Safari, Firefox, Chrome, Internet Explorer, EDGE...).
- Mobile Browsers: All pages were tested on all current mobile browsers (Native browser, Chrome, Safari...).
- OS: All pages were tested on all current OS (Windows, Android, iOS, Mac...).
- Pixel perfect: Pages are close to pixel perfect. Depending on the quality of the creatives, you may not be 100% accurate, but your page needs to be close to your template.
- Reading direction: All pages need to be tested for LTR and RTL languages if they need to be supported.
Notes: For a complete understanding of image optimization, check the free ebook Essential Image Optimization from Addy Osmani.
- Optimization: All images are optimized to be rendered in the browser. WebP format could be used for critical pages (like Homepage).
- Picture/Srcset: You use picture/srcset to provide the most appropriate image for the current viewport of the user.
- Retina: You provide layout images 2x or 3x, support retina display.
- Sprite: Small images are in a sprite file (in the case of icons, they can be in an SVG sprite image).
- Width and Height: Set
<img>if the final rendered image size is known (can be omitted for CSS sizing).
- Alternative text: All
<img>have an alternative text which describe the image visually.
asyncor deferred using
- Modernizr: If you need to target some specific features you can use a custom Modernizr to add classes in your
Scan and check your web site
- Cross Site Request Forgery (CSRF): You ensure that requests made to your server-side are legitimate and originate from your website / app to prevent CSRF attacks.
- Content Type Options Prevents Google Chrome and Internet Explorer from trying to mime-sniff the content-type of a response away from the one being declared by the server.
Cookie size: If you are using cookies be sure each cookie doesn't exceed 4096 bytes and your domain name doesn't have more than 20 cookies.
- Third party components: Third party iframes or components relying on external JS (like sharing buttons) are replaced by static components when possible, thus limiting calls to external APIs and keeping your users activity private.
Preparing upcoming requests
- DNS resolution: DNS of third-party services that may be needed are resolved in advance during idle time using
<link rel="dns-prefetch" href="https://example.com">
- Preconnection: DNS lookup, TCP handshake and TLS negociation with services that will be needed soon is done in advance during idle time using
<link rel="preconnect" href="https://example.com">
- Prefetching: Resources that will be needed soon (e.g. lazy loaded images) are requested in advance during idle time using
<link rel="prefetch" href="image.png">
- Preloading: Resources needed in the current page (e.g. scripts placed at the end of
<body>) in advance using
<link rel="preload" href="app.js">
- Google PageSpeed: All your pages were tested (not only the homepage) and have a score of at least 90/100.
Notes: You can watch the playlist A11ycasts with Rob Dodson
- H1: All pages have an H1 which is not the title of the website.
- Headings: Headings should be used properly in the right order (H1 to H6).
- Role banner:
- Role navigation:
- Role main:
- Specific HTML5 input types are used: This is especially important for mobile devices that show customized keypads and widgets for different types.
- Label: A label is associated with each input form element. In case a label can't be displayed, use
- Accessibility standards testing: Use the WAVE tool to test if your page respects the accessibility standards.
- Keyboard navigation: Test your website using only your keyboard in a previsible order. All interactive elements are reachable and usable.
- Screen-reader: All pages were tested in a screen-reader (VoiceOver, ChromeVox, NVDA or Lynx).
- Focus style: If the focus is disabled, it is replaced by visible state in CSS.
- Google Analytics: Google Analytics is installed and correctly configured.
- Headings logic: Heading text helps to understand the content in the current page.
- sitemap.xml: A sitemap.xml exists and was submitted to Google Search Console (previously Google Webmaster Tools).
- robots.txt: The robots.txt is not blocking webpages.
🛠Test your robots.txt with Google Robots Testing Tool
- Structured Data: Pages using structured data are tested and are without errors. Structured data helps crawlers understand the content in the current page.
📖Introduction to Structured Data - Search - Google Developers
🛠Test your page with the Structured Data Testing Tool
🛠Complete list of vocabularies that can be used as structured data. Schema.org Full Heirarchy
- Sitemap HTML: An HTML sitemap is provided and is accessible via a link in the footer of your website.
The Front-End Checklist is also available in other languages. Thanks for all translators and their awesome work!
🇯🇵Japanese: miya0001/Front-End-Checklist 🇪🇸Spanish: eoasakura/Front-End-Checklist-ES 🇨🇳Chinese: JohnsenZhou/Front-End-Checklist 🇰🇷Korean: kesuskim/Front-End-Checklist 🇧🇷Portuguese: jcezarms/Front-End-Checklist 🇻🇳Vietnamese: euclid1990/Front-End-Checklist 🇹🇼Traditional Chinese: EngineLin/Front-End-Checklist
Front-End Checklist Badge
If you want to show you are following the rules of the Front-End Checklist, put this badge on your README file!
Open an issue or a pull request to suggest changes or additions.
The Front-End Checklist repository consists of two branches:
This branch consists of the
README.md file that is automatically reflected on the Front-End Checklist website.
This branch will be used to make some significant changes to the structure, content if needed. It is preferable to use the master branch to fix small errors or add a new item.
Check out all the super awesome contributors.
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