Bootstrap vs Flat UI
Head-to-head usage across the sites we track.
Top sites by authority
Bootstrap · Flat UI · how many of each technology's sites sit in the web's highest authority tiers
Open Page Rank 9+
180
1
Open Page Rank 8+
3,860
16
Open Page Rank 7+
18,993
29
Open Page Rank 6+
40,203
39
Open Page Rank 5+
74,817
57
Open Page Rank scores 0 to 10 from the open web link graph; 9+ covers only a few hundred domains worldwide.
By country
Bootstrap · Flat UI · share of sites in each country using one or the other
United States
886,770
341
India
429,293
233
Germany
322,762
180
United Kingdom
295,976
244
France
279,130
154
Brazil
273,285
131
Italy
251,088
152
Spain
202,979
162
Audience countries from the Chrome UX Report, top markets of either technology.
Real user performance
| Metric | Bootstrap | Flat UI |
|---|---|---|
| LCP | 1.8 s | 2.1 s |
| INP | 75 ms | 75 ms |
| CLS | 0 | 0 |
| TTFB | 800 ms | 900 ms |
Median site's p75 values from the Chrome UX Report, Jun 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.
Bootstrap to Flat UI
| Domain | When |
|---|---|
| wisconsinhealthnews.com | Nov 2025 |
| virtualrealpassion.com | Jul 2025 |
Flat UI to Bootstrap
| Domain | When |
|---|---|
| wisconsinhealthnews.com | Nov 2025 |
| virtualrealpassion.com | Jul 2025 |