Polyfill.io
757,000 websites

Polyfill.io is free to use

https://polyfill.io/v3/

Polyfill is a service which accepts a request for a set of browser features and returns only the polyfills that are needed by the requesting browser.

VS

Spin JS
456,729 websites

Spin JS is free to use

http://spin.js.org/

Spin.js dynamically creates spinning activity indicators that can be used as resolution-independent replacement for AJAX loading GIFs.

Market Share by Top Websites

1 Polyfill.io is leading in Top 10K Sites, Top 100K Sites, Top 1M Sites and The Entire Web.

2 In terms of market share, Spin JS is clearly lagging behind, losing to Polyfill.io in all segments.

Websites Categories

1 Spin JS has better usage coverage in more websites categories. Including Science & Education, Computers Electronics & Technology, Arts & Entertainment, Travel & Tourism and 13 other categories.

2 Polyfill.io is leading in Lifestyle, Food & Drink, Law & Government, Business & Consumer Services and 3 other categories.

Geography

1 Polyfill.io is leading in most countries, including United States, United Kingdom, Canada, Japan and 145 other countries.

2 Spin JS is leading in Russia, Taiwan, Poland, Greece and 12 other countries.