Data sources
Our own index. Real public sources.
We build our own link index from 3B+ pages of the public web and enrich it with independent public datasets. Nothing is estimated from samples or bought from data brokers, so there is no third-party data fee to pass on.
Sources
Where each signal comes from
Each source is the authoritative record for its data type, or the most rigorous public dataset in its category.
- developers.google.com
Google PageSpeed Insights
PerformancePage performance and Core Web Vitals. Refresh: Not stated
Google's public API that runs a Lighthouse audit on a page and returns Core Web Vitals (LCP, CLS, INP). Where Google has enough real-user data for the page, the response also carries Chrome UX Report field data from opted-in Chrome users. We query it live when you ask for page performance, so the numbers are Google's, not ours.
- tranco-list.eu
Tranco top 100K
Domain rankDomain popularity rank. Refresh: Weekly
A research-grade domain popularity ranking developed by academics at KU Leuven and imec-DistriNet, designed to address the known manipulability of single-source popularity lists. Tranco combines several independent sources and applies a rank aggregation algorithm to produce a stable, manipulation-resistant list. We keep its top 100,000 domains and refresh them weekly.
- web.archive.org
Internet Archive (CDX API)
HistoryFirst-seen and last-seen dates and snapshot counts. Refresh: Not stated
The Internet Archive has been archiving the public web since 1996. Its CDX (Capture Index) API exposes structured metadata about every snapshot it holds. We use it to surface when a domain was first and last seen in the archive and roughly how many snapshots exist.
- rdap.org
RDAP / WHOIS Registries
Domain ageDomain age and registrar. Refresh: Not stated
RDAP (Registration Data Access Protocol) is the IETF-standardized replacement for WHOIS, now operated by all major domain registries and registrars. Unlike WHOIS, which returns free-form text requiring brittle parsing, RDAP returns structured JSON directly from authoritative registry operators. We use RDAP to compute domain age and identify registrars. Data comes directly from the registry, not from a third-party aggregator.
Freshness and cadence
The core link graph is updated quarterly. Enrichment signals refresh on their own schedules: popularity rank weekly, domain age is looked up from the registry and cached for 30 days, and technology stack is detected in real time. Quarterly freshness covers the overwhelming majority of use cases: link building, lead enrichment, competitive analysis, AI agent workflows, and programmatic SEO. If you need daily link change monitoring, that's a different product category, and Ahrefs is the right tool for it. Most developers building on an API don't.
What we don't do
The link graph and authority scores are built from public web data we process, not from scraping websites on demand. A handful of real-time endpoints (page SEO, tech stack, site health, sitemap, crawl history and page performance) look up the page you ask about when you ask. We do not purchase data from third-party data brokers. We do not interpolate or estimate metrics where primary data is unavailable: if a domain has no backlinks in the dataset, the API returns an empty result, not a guess. Every value returned by the API traces back to public web data we process or to the registries and datasets listed above.