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DNS Checker(beta)

Reverse WHOIS Lookup

Search 184M+ domain records by registrar, nameserver provider, TLD, or date range. Discover portfolios, monitor brands, and research domain infrastructure across 1,200+ TLDs.

“Reverse WHOIS finds every domain registered by a person or organization. The internet is smaller than you think.”

Written by Ishan Karunaratne · Last reviewed:

What Is Reverse WHOIS?

A reverse WHOIS lookup flips the traditional domain lookup on its head. Instead of starting with a domain name and finding its registration details, you start with a characteristic — like a registrar name, nameserver provider, or TLD — and find all domains matching that criteria.

I built this tool to make it easy to explore the domain landscape. Whether you are monitoring your brand across registrars, analyzing a competitor's domain portfolio, or researching which domains are managed by a specific provider, reverse WHOIS gives you the answers without manual lookups.

What Are the Use Cases for Reverse WHOIS?

Brand Monitoring

Find domains registered through your registrar or using your nameservers. Detect unauthorized use of your brand across the domain ecosystem.

Competitor Analysis

Discover domains managed by the same registrar or DNS provider as a competitor. Understand their domain strategy and infrastructure choices.

Portfolio Discovery

Search for domains by TLD and date range to find recently registered or soon-to-expire domains in specific extensions.

Provider Research

See how many domains use a specific DNS provider like Cloudflare or AWS Route 53. Useful for market research and provider evaluation.

How Do You Use Reverse WHOIS?

  1. Enter at least one filter: registrar name, nameserver provider, or TLD. Use the quick-pick buttons for popular values.
  2. Optionally narrow results with date ranges for creation or expiry dates.
  3. Choose your sort order: relevance, created date, or expiry date.
  4. Click Search to see matching domains with total count. The first 50 results are free.
  5. Scroll down to load more results. Each additional page of 50 uses 1 lookup from your daily quota.

Why Use DNS Checker for Reverse WHOIS?

Most reverse WHOIS tools are either paywalled from the first query, limited to a handful of TLDs, or require you to search by registrant name only — which is largely useless in a post-GDPR world where personal data is redacted from public WHOIS records. DNS Checker's Reverse WHOIS takes a different approach by focusing on the metadata that remains publicly available: registrar, nameserver provider, TLD, and registration dates.

The search runs against a database of 184M+ domain records covering 1,200+ TLDs, refreshed daily. This means results reflect the current state of the domain landscape, not a stale snapshot from weeks ago. The first page of results (50 domains) is always free — no account required, no credit card, no paywall on the initial search.

What makes this particularly powerful is the integration with DNS Checker's full tool suite. A reverse WHOIS search surfaces domains, but then you can drill into any result using the WHOIS Lookup for full registration details and a 7-point security validation, the DNS Inspector for DNS record analysis, or the Website Reputation Checker to flag malicious domains. No other reverse WHOIS tool provides this end-to-end workflow.

Complete Domain Intelligence Workflow

DNS Checker offers six WHOIS and domain research tools that work together as a complete domain intelligence workflow — from individual lookups to portfolio-scale analysis:

WHOIS LookupFull WHOIS data for any domain with a 7-point validation checklist, EPP status decoding, and PDF export.Reverse WHOISSearch 184M+ records by registrar, nameserver provider, or TLD to discover domain portfolios.You are hereBulk WHOISLook up WHOIS records for multiple domains at once — ideal for portfolio auditing.Domain Age CheckerPrecise registration age in years, months, and days for SEO analysis and domain valuation.Domain Expiry CheckerColor-coded expiry countdown with lock status verification and renewal monitoring.Expiring DomainsBrowse domains expiring across 184M+ records. Filter by TLD, length, and age for acquisition.

Together, these tools cover the full domain lifecycle from registration through expiry — with 184M+ records, daily updates, and cross-tool integration that no single WHOIS lookup service provides on its own.

Need this in code?

Every check this tool runs is also available via the reverse WHOIS API with examples in cURL, JavaScript, Python, PHP, Ruby, and Java.

API docs

Related tools you might need

Built and maintained alongside this tool. Free, no signup required.

Standard WHOIS lookupLook up a single domain's registration details.Reverse IP domain checkFind every domain hosted on a specific IP.Reverse nameserver lookupFind every domain delegated to a specific nameserver.Bulk WHOIS lookupLook up many domains in one call.

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