Uncover hidden subdomains, map attack surfaces, and reveal competitor properties — all in one free tool.
SEO professionals and security experts often miss critical assets because subdomains stay hidden. Manual enumeration is slow, incomplete, and error-prone.
SEOScaleUp Subdomain Finder instantly maps every known and potential subdomain for any domain using passive DNS + certificate transparency logs — zero configuration.
Find forgotten assets before attackers
Discover hidden competitor properties
From DNS enumeration to metadata insights — built for speed and depth.
Access over 2B subdomain records from global scans.
Check A, CNAME, TXT records on discovered subdomains instantly.
Find subdomains via SSL/TLS certificates logs.
Scan up to 100 domains at once with CSV import.
One-click export for further analysis.
Identify web servers, frameworks per subdomain.
View subdomain changes over time (Wayback Machine integration).
Scan from multiple geographic nodes.
Programmatic subdomain enumeration.
Three intelligent steps to full subdomain enumeration.
Type any domain, subdomain or root.
We query 15+ sources (DNS, CT logs, search engines).
Real-time DNS resolution & status codes.
CSV export + interactive table.
Actionable intelligence without heavy infrastructure.
Uncover staging, dev, admin panels you never knew existed.
Security teams rely on us for continuous asset monitoring.
Monitor rival subdomains and their new product launches.
Practical applications across industries.
Engineered for accuracy at scale.
Daily updated subdomain indexes from global anycast network.
Cross-validation across 8+ sources ensures accuracy.
No logs, no tracking. All scans are anonymous.
Why our subdomain finder outranks both manual and expensive tools.
| Feature | SEOScaleUp | Manual/Free Alt | Expensive Paid ($99+) |
|---|---|---|---|
| Total subdomains indexed | 2B+ | Limited (~500K) | 1.5B |
| Live DNS resolution | ✓ | ✗ | ✓ |
| Certificate transparency logs | ✓ | ✗ | ✓ |
| Bulk domain scan | ✓ (100 domains) | ✗ | ✓ (limited) |
| Tech stack detection | ✓ | ✗ | ~ |
| API access | ✓ Free tier | ✗ | ✓ expensive |
| Historical subdomain changes | ✓ | ✗ | ✓ |
| Export CSV/JSON | ✓ | ~ | ✓ |
| Price | Free forever | Freemium | $99+/mo |
Our tool aggregates from over 15 sources, including certificate transparency logs, DNS datasets, and search engines. Accuracy exceeds 98% with live verification.
No signup required. All core features are completely free without registration.
Yes, SEOScaleUp offers a REST API with rate limits suitable for security pipelines. Free tier includes 500 requests/day.
Passive enumeration uses existing data without touching target servers — stealthy and safe. Active sends DNS probes. We use both to maximize coverage.
Daily incremental updates and weekly full refreshes across all data sources.
Yes, for domains you own or have permission to test. Always comply with local laws and terms of service.
Yes, we detect and flag wildcard DNS records to avoid false positives.
Absolutely — CSV, JSON, and even PDF reports are available with one click.
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