Optimizely vs UserZoom
Head-to-head usage across the sites we track.
Top sites by authority
Optimizely · UserZoom · how many of each technology's sites sit in the web's highest authority tiers
Open Page Rank 9+
32
2
Open Page Rank 8+
398
6
Open Page Rank 7+
1,140
21
Open Page Rank 6+
1,815
23
Open Page Rank 5+
2,633
27
Open Page Rank scores 0 to 10 from the open web link graph; 9+ covers only a few hundred domains worldwide.
By country
Optimizely · UserZoom · share of sites in each country using one or the other
United States
25,713
83
Canada
6,439
59
India
5,059
64
United Kingdom
4,863
60
Australia
4,155
47
Germany
3,558
51
France
3,449
48
Spain
3,393
52
Audience countries from the Chrome UX Report, top markets of either technology.
Real user performance
| Metric | Optimizely | UserZoom |
|---|---|---|
| LCP | 1.9 s | 2.1 s |
| INP | 100 ms | 125 ms |
| CLS | 0.05 | 0 |
| TTFB | 800 ms | 800 ms |
Median site's p75 values from the Chrome UX Report, Sep 2026. Lower is better; green meets Google's "good" threshold. This describes the sites that use each technology, not the technology's own overhead.
Sites that switched
Domains that dropped one technology and adopted the other within about a year, data nobody else gives away free.
Optimizely to UserZoom
| Domain | When |
|---|---|
| redhat.com | Jan 2026 |