Outlook Web App vs RoundCube
Head-to-head usage across the sites we track.
Top sites by authority
Outlook Web App · RoundCube · how many of each technology's sites sit in the web's highest authority tiers
Open Page Rank 8+
11
73
Open Page Rank 7+
29
243
Open Page Rank 6+
50
378
Open Page Rank 5+
68
544
Open Page Rank scores 0 to 10 from the open web link graph; 9+ covers only a few hundred domains worldwide.
By country
Outlook Web App · RoundCube · share of sites in each country using one or the other
United States
3,011
917
India
1,731
690
Germany
1,446
827
United Kingdom
1,538
583
France
1,326
597
Spain
1,125
504
Canada
1,313
313
Netherlands
1,098
525
Audience countries from the Chrome UX Report, top markets of either technology.
Real user performance
| Metric | Outlook Web App | RoundCube |
|---|---|---|
| LCP | 1.7 s | 1.5 s |
| INP | 75 ms | 75 ms |
| CLS | 0 | 0 |
| TTFB | 700 ms | 600 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.