NDL Web Archiving Project (WARP) review
A free national web archive for searching preserved websites, not submitting arbitrary URLs.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
WARP is the National Diet Library of Japan’s web archive, collecting and preserving websites such as public institutions’ sites and selected sites archived with publishers’ permission. It is suited to researchers and other visitors looking for preserved Japanese web material, rather than teams that need to capture arbitrary URLs on demand. The service is free and available through the web, with API access for archive resources. Its collection is managed by the NDL, not controlled by individual users.
Search covers full-text archived page content, with refiners for crawl date, domain or URL, title, publisher, content type, and organization type. Visitors can search website records, browse archived versions, and see website archive dates and metadata on detail pages. Supported material includes HTML, PDF, Microsoft Word, RTF, Excel, CSV, TSV, PowerPoint, text, and EPUB. Captures include an archive banner with capture information. Memento TimeMap and TimeGate endpoints offer a way to access archived resources programmatically; browser access is supported in current Chrome, Firefox, and Edge.
WARP’s main constraint is its collection and access model: the NDL operates recurring crawler schedules, and collection eligibility depends on law or publisher permission. Some material is available online, while other items can only be accessed at NDL premises. Some formats, dynamic content, or very large pages may not be captured. That makes WARP a fit for people researching material already in Japan’s national archive, especially when detailed search and archived versions matter. Organizations that require user-directed captures, control over crawl schedules, or guaranteed access to every archived item should consider a different kind of archiving service.
NDL Web Archiving Project (WARP) pros and cons
- Where it wins
- Search archived page content with detailed filters for dates, publishers, and formats.
- Browse archived versions and view capture dates and website metadata.
- Access archive resources through Memento TimeMap and TimeGate endpoints.
- Where it doesn't
- Does not let users submit arbitrary URLs for capture.
- Access to some archived material is limited to NDL premises.
- Some formats, dynamic pages, and very large content may not be archived.
NDL Web Archiving Project (WARP) fact sheet, pricing and score →
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