Frontend Checklist for Websites

Performance

General

• HTTP/2 is being used
• CDN is used for static files
• CDN is used for content pages
• Cookie-Less Domain is used for static files
• DNS prefetching is used
  • <link rel="preload" as="script"> (CSS, JS and fonts)
  • <link rel="dns-prefetch"> (for Domain, which provides static resources, eg.: Images, and Tracking Tools)

Resources

• JavaScript combined in one file

• JavaScript minified

• JavaScript is compressed

• No JavaScript inline

• CSS combined in one file

• CSS minified

• CSS is compressed

• CSS: No usage of @import

• No CSS inline

• HTML minified

• Static files are compressed with gzip or brotli

• Static files are pre-compressed on the server

• HTML is compressed with gzip or brotli

• Usage of correct image formats

• Usage of responsive images

• Images are optimized (ImageOptim…)

• Image are cached in the browser

• SVG files are minized

• SVG files are used where possible

• Only fonts that are used are loaded

• Browser cache is used efficiently

• ETags is not used

• Expires, cache-control and max-age headers for static resources is set to 1 year

• Asychronous or deferred loading of non-critical content

• Tracking scripts loaded asynchronously

Measurements

Usually I measure the main pages of a project here.

• Count of all files
• Size of all files combined
• Download time of the page
• Google Page Speed analysis (Desktop, Mobile and Mobile UX; x of 100)
• SpeedIndex

Rendering Performance

• Intrinsic image sizes are specified in the markup
• CSS is loaded in the document head
• Scripts are loaded at the end of the document
• Scripts are loaded with defer-attribute
• Scripts are loaded in the document head after styles are loaded
• Scrolling is possible with 60fps
• No usage of document.write
• CSS animation causing layout(reflow) is not heavily used

Device performance

• CPU usage
• Memory usage
• GPU usage

Cross-Browser

• Website is loading on all current desktop browsers (Safari, Firefox, Chrome, IE11, EDGE)
• Website is loading on all current mobile browser (Chrome for Android, iOS Safari)
• For Shops: Checkout is usable on all necessary devices and browsers
• Viewport Meta Tag is used correctly
• Usage of correct input types

SEO

• Pages can be indexed

• Mobile version of website is available

• HTTPS is used on all pages

• Sitemap is available

• Structured-Data is used where possible

• Headlines used

• Headlines in correct order

• Meta descriptions used

• Meta keywords used

• Meta title is filled correctly

• Keywords used in headlines

• Images use the alt-attribute

• Links use a title-attribute

• Links in navigation do not use title-attribute

• No Duplicate Content

• Usage of absolute URLs

• Internal links point to HTTPS version of page

• Redirects are done with 301

• No 404-errors

• No 500-errors

• Canonical Tags are used if applicable

• Ratio of code and content is around 25% for shop pages and 50% for content pages

Accessibility

• Color Contrast is good (WCAG 2.0)
• WAI-ARIA roles are used
• Usage of accessible elements like nav, footer, aside
• URLs are accessible
• Keyboard accessibility is available
• Correct input types are used

Security

• HTTPS is used on all pages
• There is no mixed content on the pages
• external plugins and trackings get loaded via HTTPS
• Robots.txt is in use
• Cross-Site-Scripting is not possible
• HSTS Header is set
• Content-Security-Policy is set and only allows specific hosts and no inline scripts

More

• Strict usage of domain with or without www
• Correct language set in HTML tag
• Charset is set
• HTML is valid
• 404-page is available
• A special print style sheet is in place

Server

• Correct language set by the server
• Correct content types set by the server