CSS Prefixer
? Frequently Asked Questions
What are vendor prefixes?
Vendor prefixes (-webkit-, -moz-, -ms-, -o-) are added to CSS properties for browser-specific implementations of experimental features. For example, -webkit-transform for older Safari browsers before the standard was finalized.
Do I still need vendor prefixes in 2025?
Less than before, but yes for older browser support. Modern CSS features work unprefixed in current browsers, but prefixes ensure compatibility with older versions (Safari 3-4 years old, older mobile browsers).
Which properties need prefixing?
Common prefixed properties include flexbox, transforms, transitions, animations, gradients, grid (older), and appearance. The tool automatically knows which properties need prefixes and for which browsers.
Can I control which prefixes are added?
Some tools let you specify target browsers and versions (e.g., "last 2 versions" or "IE 11"). This generates only necessary prefixes, avoiding bloat from obsolete browser prefixes.
Does prefixing increase file size significantly?
Yes, prefixing can increase CSS size by 20-40% depending on how many prefixed properties you use. However, this is necessary for compatibility and is reduced through minification and compression.
Is my data safe and secure?
Yes, absolutely! This tool runs entirely in your browser. All data processing happens locally on your device - nothing is uploaded to our servers. Your files and data never leave your computer, ensuring complete privacy and security.