Polyfill.io on new websites
Polyfill.io, an on-demand JavaScript polyfill service whose domain changed owner in 2024 and was then used to serve malicious code.
- Sites using Polyfill.io
- 116
- since May 2026
- Last 30 days
- 0.0%
-
of new sites, to Oct 19
no change on the 30 days before - Last 7 days
- 0.0%
- of new sites, 7-day average
no change on the week before
| First seen | May 4, 2026 |
|---|---|
| Last seen | Oct 19, 2026 |
What we found
- Polyfill.io appeared on about 47 new sites in the last 30 days.[1]
- Six in ten new Polyfill.io sites also use jQuery.
- It is unusually common on .site domains: 11% of the domains running it, against 2.5% of domains across new sites.
Share of new sites using Polyfill.io
The line is the 7-day average share of new sites that use Polyfill.io, since 10 September.
Who uses Polyfill.io
| Type | Sites | Share | Bar |
|---|---|---|---|
| Education | 6 | 22.2% | |
| Health | 4 | 14.8% | |
| Design | 3 | 11.1% | |
| Finance | 3 | 11.1% | |
| Productivity | 3 | 11.1% | |
| AI | 2 | 7.4% | |
| E-commerce | 2 | 7.4% | |
| Content | 1 | 3.7% | |
| Games | 1 | 3.7% | |
| Marketing | 1 | 3.7% | |
| Social | 1 | 3.7% |
| Country | Sites | Share | Bar |
|---|---|---|---|
 UK |
5 | 15.2% | |
 India |
5 | 15.2% | |
 France |
4 | 12.1% | |
 Iran |
4 | 12.1% | |
 Netherlands |
3 | 9.1% | |
 Australia |
2 | 6.1% | |
 Brazil |
2 | 6.1% | |
 Ukraine |
2 | 6.1% | |
 Bangladesh |
1 | 3.0% | |
 Canada |
1 | 3.0% | |
 Switzerland |
1 | 3.0% |
| Ending | Sites | Share | Bar |
|---|---|---|---|
| .com | 58 | 50.0% | |
| .in | 6 | 5.2% | |
| .fr | 5 | 4.3% | |
| .org | 5 | 4.3% | |
| .uk | 5 | 4.3% | |
| .app | 4 | 3.5% | |
| .nl | 4 | 3.5% | |
| .au | 3 | 2.6% | |
| .dev | 3 | 2.6% | |
| .net | 3 | 2.6% | |
| .online | 3 | 2.6% |
Javascript Library on new sites
| # | Movement | Tool | Share of category[3] | Bar | |
|---|---|---|---|---|---|
| 1 | – |
jQuery
|
34.4% | ||
| 2 | – |
React Router
|
16.2% | ||
| 3 | – |
Motion
|
14.5% | ||
| 4 | – |
TanStack Router
|
10.7% | ||
| 5 | – |
Swiper
|
8.2% | ||
| … | |||||
| 354 | ▲43 | Polyfill.io | <0.1% | ||
All-time shares across the new sites we track: of all of them, and of the sites using any Javascript Library tool. Polyfill.io is typically used alongside jQuery rather than instead of it. Among September launches it ranked #339 in Javascript Library, up from #382 in August. All 1553 in Javascript Library
Often used with Polyfill.io
| Tool | Sites with both | vs all new sites |
|---|---|---|
Bootstrap
|
44 | 8.9x |
jsDelivr
|
44 | 8.7x |
Font Awesome
|
48 | 6.3x |
|
jQuery
|
68 | 4.2x |
Google Analytics
|
39 | 3.3x |
Tools that turn up far more often on Polyfill.io sites than on new sites in general, and how many times as common each one is there.
Recently launched products built on Polyfill.io
8 of the 116 sites using Polyfill.io are product launches we list individually. The other 108 are new business and personal sites: they count towards the figures above but are not listed here. A watch sends them to you.
Iceland
Watches, exports and the API give you all 116 sites using Polyfill.io, from £15 a month.
Notes
- These figures cover websites that went live since April 2026, not the web as a whole.
- Country comes from what each site says about itself, such as a company registration, legal terms or a phone number, not just its domain ending. Too few sites state their country plainly for the usual count, so this one also counts single signals: a country domain ending, a phone number (for North America, its area code), a location the site declares in its own page metadata, or a country-specific vendor stack and the page language where they agree and nothing contradicts them. Read these as likely rather than certain.
- Some products people expect to see here are filed under a related category: UI Library.
How this page is made
FirstSited looks at each new website near the day it goes live and records what it was built with. We do not go back later, so these figures describe what sites launch with, not what they run today. A site counts towards Polyfill.io when we detect Polyfill.io on it at that look.
Every share on this page is a proportion of the new sites we were tracking at the time. Sites we found across the wider web count towards the figures, but only product launches are listed by name. How we detect technologies · How we find new sites