What powers 21th-books.com?
Last seen Jun 2026 · 17 technologies across 14 categories
Advertising
Twitter Ads
since Oct 2022
Analytics
Google Analytics
since Oct 2022
CDN
CMS
WordPress
since Oct 2022
Databases
MySQL
since Oct 2022
Hosting
Sakura Internet
since Oct 2022
JavaScript libraries
Miscellaneous
Open Graph
since Oct 2022
Programming languages
PHP
since Oct 2022
Security
Cloudflare Bot Management
since Mar 2025
Tag managers
Google Tag Manager
since Aug 2023
Web servers
Nginx
since Oct 2022
Widgets
Twitter
since Oct 2022
WordPress plugins
Audience
- 100% phone
Japan
Countries where the site has Chrome traffic, strongest markets first.
Open Page Rank
0.48 / 10 · ranked #25,876,760 of all domains
3 referring domains · OpenPageRank
Core Web Vitals
| LCP | 1.3 s |
| CLS | 0 |
Real user p75, Chrome UX Report, Jun 2026.
Page
- Language: Japanese
- Weight: 2.1 MB · 52 requests
- Structured data: OpenGraph, Twitter Cards
Homepage as crawled by the HTTP Archive, Jul 2026.
Full technology history →
Report an incorrect detection
Recent changes
- detected Cloudflare Apr 2026
- detected Cloudflare Bot Management Apr 2026
- dropped Cloudflare Nov 2025
- dropped Cloudflare Bot Management Nov 2025