Debug: upstream API calls (click to expand)
How it works
The Subdomain Finder lists every subdomain of a root domain that has organic-search visibility. It then adds traffic and link-authority metrics to each one from two independent sources at the same time.
Stage 1: find the subdomains. For each root domain you submit, we call get-matching-domains on our keyword index. It returns every domain in the index whose host ends in your root. For example.com that means blog.example.com, shop.example.com, www.example.com, and so on. The list is capped at 100 subdomains per root on the Free plan. It is sorted by traffic, highest first, so the most important subdomains come first.
Stage 2: add the metrics. For each subdomain, in parallel batches, we run two separate lookups.
- Moz fields from our local copy of the domains database: Domain Authority, Page Rank, Spam Score, Followed Linking Domains, pages linking to the subdomain, and root domains linking to it. No external API call is needed.
- Traffic and Total Keywords from our keyword index, batched per subdomain. A subdomain the index has no data for shows as No data, not zero.
Stage 3: compute Website Authority. Each row gets one 0 to 100 Website Authority score. It blends half of DA, three tenths of PR scaled to 100, and two tenths of log-scaled Followed Linking Domains. A missing PR counts as 0. The Website Authority Checker uses the same formula.
Single and bulk mode. Single mode takes one root domain in a textbox. Bulk mode takes up to 2 roots per submission, one per line, and groups the results by root in one table.
Choosing the www variant. We first run your input through get-matching-domains to settle example.com against www.example.com. Without that step the results would mix the two variants in confusing ways.
Plan caps.
- Roots per submission: 2 on the Free plan.
- Subdomains per root: 100.
- Daily jobs: 500, shared with the Domain Authority Checker, Website Authority Checker, and Spam Score Checker.
Known limitations.
- Index only. A subdomain that ranks for no keyword in Google will not appear. That usually means staging sites, admin panels, and brand-new subdomains. For a full DNS-level list, use a security tool.
- Refresh lag. A newly published subdomain takes a few days to several weeks to reach our index. It depends on how fast Google indexes it and how often we refresh.
- Partial rows. Some subdomains have Moz data but no traffic data, or the reverse, because the two sources refresh on different schedules. The row still shows, with the missing cells as muted dashes.
What the columns mean
- Subdomain
- The full subdomain we found, without
http(s)://. Click it to open the subdomain's homepage in a new tab. Click the cross-tool icon to inspect it in other tools. - Traffic
- Estimated monthly organic-search visits to this subdomain, using the same method as the Website Traffic Checker. It shows which of a competitor's subdomains bring in the traffic.
- Total Keywords
- The number of distinct keywords this subdomain ranks for in Google. Higher means a broader topical footprint.
- DA (Domain Authority)
- Moz's 0 to 100 prediction of ranking strength. Each step up is harder than the last, so moving from 30 to 40 is real progress and 80 to 90 is much harder. Subdomains often have a lower DA than their root because Google ranks them as separate sites.
- PR (Page Rank)
- A 0 to 10 score based on Google's original PageRank idea, computed from the public link graph. A useful second opinion on authority.
- WA (Website Authority)
- Our blended 0 to 100 score: half DA, three tenths PR scaled to 100, and two tenths log-scaled Followed Linking Domains. It smooths over cases where DA alone ranks variants wrongly.
- Spam
- Moz's Spam Score, 0 to 100. Higher means more spam signals. Use it to spot subdomains that may carry penalty risk before you buy or link to them.
- Ref Domains
- The number of distinct domains with at least one followed link to this subdomain. The main measure of link diversity.
- Ref Backlinks
- The total number of followed backlinks to this subdomain. One referring domain often sends several backlinks, and this column counts them all.
- Root Domain (bulk mode only)
- Which of your submitted roots this subdomain belongs to. Useful when comparing several competitors side by side.
Frequently asked questions
How do I find subdomains of a domain?
Enter the root domain (such as example.com) above and click Find Subdomains. We search our index for every subdomain we know of, such as blog.example.com, shop.example.com, and support.example.com. Each one gets traffic, Domain Authority, Page Rank, Website Authority, Spam Score, referring domains, and referring backlinks. Bulk mode takes up to 2 root domains in one job on the Free plan.
What is the best tool for finding subdomains?
It depends on the job. For security research, tools like Subfinder, Amass, and Sublist3r combine certificate logs, passive DNS, and wordlist guessing to find every subdomain on a target, including dev, staging, and internal ones. For SEO research, those tools return a lot of noise. This tool covers only subdomains with indexed organic traffic, because those are the ones you can compete with or learn from. Pick the tool that fits your use case.
What is a subdomain?
A subdomain is a domain one level below a registered root. If example.com is the root, then blog.example.com, shop.example.com, and www.example.com are all subdomains. Each subdomain can serve different content from a different server, and search engines rank each one on its own. www is the traditional subdomain for the homepage. That is why most sites answer at both www.example.com and example.com.
What is the difference between a domain and a subdomain?
The domain is what you register with a registrar: the name plus the ending, as in example.com. A subdomain is any prefix you add to it. Your DNS settings control subdomains, not your registrar. You can add as many subdomains as you like to a domain you own without buying anything. You just point new DNS records wherever you want them to go.
What is subdomain enumeration?
Subdomain enumeration is the security practice of finding every subdomain that resolves on a target, even ones the public site never links to. Common sources are certificate-transparency logs, passive DNS databases, search-engine indexes, and wordlist guessing against DNS. This tool covers only the search-engine part: subdomains in our index because they rank in Google. For a full list, including staging environments that are not indexed, use a security tool like Subfinder or Amass.
Can a subdomain be a separate website?
Yes. A subdomain can host a different application on a different server, with its own SEO footprint and audience. Google mostly treats each subdomain as a separate site for ranking. That is why a new subdomain starts with a clean SEO slate even on an established root. It is also why finding subdomains helps SEO research: a competitor's blog subdomain may be the real traffic driver, and you would never see that from the root alone.
Why does the list not match what I see in my hosting panel?
Two reasons. First, we return only subdomains that appear in our organic-keyword index. A new staging subdomain or one with no public content will not show up. Second, our index refreshes with a lag, so subdomains added in the last week or two may not be in the data yet. For a complete list of every subdomain on your own systems, your DNS provider's zone file is the source of truth, not this tool.
Do all subdomains rank in Google?
No. Only subdomains that are public and not blocked by robots.txt or a noindex tag can rank. Staging subdomains (staging.example.com), admin tools (admin.example.com), and dev environments usually do not. The subdomains in our index are the ones competing for organic traffic, which is usually what you want for SEO research. Keep in mind it is a filtered view, not a full inventory.