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ndxer · say "indexer"

DNS, looked up inside out.

Forward lookups for a hostname. From a value back to the names that carry it. Indexed across 215 million domains, with a timestamp on every row.

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Captured Investigations relationship diagram connecting reddit.com with observed domains and shared values.
Explore connections. Read the evidence. View captured example Investigations guide

The whole picture

Records
2,681,896,538
Names
431,909,705
Domains
215,165,440

. Figures marked ~ are close estimates rather than exact counts. See every figure, and what each one means.

Find the next name

See names observed around a domain.

Explore the names under a domain and matching names under other TLDs. Choose one to investigate next.

Read the Lookup guide
Captured results for utn.edu.ar, listing observed hostnames and their first and last observed dates.
View captured example

The wider view / DNS insights

See the bigger picture in DNS.

Explore record counts, common providers, and patterns across DNS.

Explore DNS insights

Follow the names behind a shared value.

These lookups return names observed carrying an address, a name server, a mail host or an SPF target. They read forward DNS observations, not PTR records.

Combine the evidence in a saved investigation, or build these questions into your tools with the DNS API. Shared DNS values are leads to review, not proof of common ownership.

Forward, clearly.

A, AAAA, CNAME, MX, NS, TXT and SOA for any hostname, with TTL and the time we last checked.

From a value back to its names.

Start from an IP, a name server, a mail host or an SPF include and get every domain we have observed carrying it — with counts, truncation flags and a shared-infrastructure warning.

Tokenized SPF and discovered hostnames.

We split SPF records into their parts and index each one, and we keep the hostnames that turn up along the way, so one token leads to the next.

Your first request

bash
curl -H "Authorization: Bearer $NDXER_API_KEY" https://api.ndxer.com/v1/me/

Pricing

Four plans from free to serious. Published prices, Subscribe buttons, no sales call.

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What ndxer does not claim

We have not seen every hostname on the Internet, we do not keep past answers after they change, and we do not promise a refresh schedule. What we do promise is that every record we hand you carries its own timestamp, its own truncation flag, and its own counts — so you can judge freshness yourself instead of trusting an adjective.

Frequently asked questions

From forward DNS records. Every value in a record — an address, a name server, a mail host, an SPF token — is indexed by the domain that carried it, and an inverse lookup reads that index backwards to return the domains observed carrying the value you asked about. It never touches PTR records.

No. ndxer does not collect, buy, or replay anyone else's DNS queries. What it holds is DNS records and when each was last observed — nothing about who asked for what.

Less complete than you would like, and we would rather say so than pretend otherwise. Each result tells you how many matches were returned, the total or estimated match count, and whether the list was truncated. A hostname we have never observed will not appear, and no flag on the response will imply otherwise.

Every record shows a last-observed or last-checked timestamp, and that timestamp is the answer. We publish no refresh schedule, because a schedule we cannot guarantee is worse than no schedule at all. Read the timestamp and decide whether it is recent enough for what you are doing.

Because the IP belongs to shared hosting, a CDN, or something similar, where thousands of unrelated hostnames sit behind one address. The list is still accurate; it just does not mean what a list of hostnames on a dedicated IP would mean. We flag it so nobody builds a conclusion on it by accident.

Security research, asset discovery on systems you own or are authorized to assess, DNS debugging, and building tools. Our Acceptable Use Policy draws the line at using ndxer against networks you have no authorization to test, and we enforce it.

No. We log lookups to run the service, enforce limits, and investigate abuse, and we keep those logs for the limited period described in our Privacy Policy. We do not sell query data, and we do not have an advertising business that would want it.

One request is one query. Each page of paginated results is its own query. A query that returns nothing still counts — we did the work either way. Input errors, rate-limit responses, and our own failures do not count against you.

Explore DNS. Keep the evidence.

250 queries a month, one API key, no card, and every lookup the product answers.

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