Best free reverse DNS (PTR) lookup tools
AdminKit resolves an IPv4 or IPv6 address to its PTR hostname with no account; ViewDNS.info, MxToolbox and nslookup.io do the same automatic IP-to-PTR conversion, verified 2026-11-04, though ViewDNS.info masks the hostname behind a sign-in prompt per AdminKit's existing test. Google Admin Toolbox Dig supports PTR lookups only once you build the reverse name yourself; dnschecker.org blocked every read.
AdminKit is built by Netbase JSC. AdminKit is listed below; ViewDNS.info, MxToolbox, nslookup.io and Google Admin Toolbox Dig are independent and not affiliated with AdminKit.
What each tool’s own page confirms
ViewDNS.info’s Reverse DNS Lookup, read 2026-11-04, describes itself plainly: “Find the reverse DNS entry (PTR) for a given IP.” The same page lists a “Reverse DNS API” among a long list of ViewDNS APIs, alongside a separate Pricing page. It requires no sign-in to submit a lookup, but per AdminKit’s existing head-to-head test against ViewDNS.info, a live query against a known IP on 2026-10-29 showed the actual hostname masked as “xxx.xxxxxx” with “Sign in to enable copy” and “Sign in to enable export” prompts — that fact is reused here with its original verification date rather than re-tested for this roundup.
MxToolbox’s Reverse Lookup, read 2026-11-04, states: “If you type in an IP address, we will attempt to locate a dns PTR record for that IP address.” The page requires no account and carries the same “Copyright 2004-2026, MXToolBox, Inc.” footer AdminKit’s existing MxToolbox comparison already cites for the company’s two-decade track record. The page itself doesn’t mention an API or state whether IPv6 addresses are supported.
nslookup.io’s PTR Lookup, read 2026-11-04, bills itself as finding “canonical name pointers (PTR DNS records),” with worked examples of 1.1.1.1 and 199.252.157.234 — both IP addresses, even though its own copy also describes the tool as working “for a domain name.” Its navigation links to “API Documentation” and a “REST API reference,” and the same site runs a much wider suite: DNS, certificate, email-security and IP/network tools listed directly in its own menu. No sign-in prompt appears anywhere on the page, and it doesn’t state whether IPv6 reverse lookups are supported.
Google Admin Toolbox Dig, read 2026-11-04, is a raw DNS query tool: a single text field plus a row of record-type buttons that includes PTR alongside A, AAAA, ANY, CAA, CNAME, MX, NS and others. Unlike the other three tools here, it does not convert an IP address into a reverse-lookup name for you — getting a PTR result means typing the full reverse name yourself (for example 8.8.8.8.in-addr.arpa), the same way the command-line dig tool works. No login or account element appears anywhere on the page, and it sits in a small Google Admin Toolbox alongside a handful of other diagnostic tools (Browserinfo, Check MX, HAR Analyzer, Log Analyzer, Messageheader, Useragent) — a much narrower set than ViewDNS.info, MxToolbox or nslookup.io.
dnschecker.org’s own reverse DNS lookup page returned an HTTP 403 response on every read-only GET attempt for this comparison on 2026-11-04, so it isn’t included here — see the FAQ for details.
What AdminKit’s own tool does
AdminKit’s reverse DNS (PTR) lookup converts the IPv4 or IPv6 address you enter into its reverse-lookup name — in-addr.arpa (RFC 1035) or ip6.arpa (RFC 3596) — automatically, and queries that name’s PTR record through the same DNS-over-HTTPS proxy as AdminKit’s general DNS lookup tool, with no account and no query logged. What it doesn’t offer today is a documented API: unlike ViewDNS.info’s and nslookup.io’s own pages, which each link to API documentation, AdminKit’s Check API is not deployed to any public host yet.
The honest angle
If you want a one-click PTR lookup that handles the in-addr.arpa/ip6.arpa conversion for you and shows the full result with no account, that’s what AdminKit’s tool does, and it’s also what ViewDNS.info, MxToolbox and nslookup.io’s own pages describe doing — though ViewDNS.info’s own masking behavior (verified separately) means you may still hit a sign-in wall there for the actual hostname. If you’re comfortable constructing a reverse DNS name yourself and want it alongside every other DNS record type in one raw query box, Google Admin Toolbox Dig’s own page confirms that’s exactly what it’s built for, with none of the IP-to-PTR convenience the others provide. None of these tools’ own pages state whether they support IPv6 reverse lookups, which is why that row above is marked unverified rather than guessed.
Trademarks belong to their respective owners; AdminKit is not affiliated with ViewDNS.info, MxToolbox, Inc., nslookup.io, or Google LLC.
| Feature | AdminKit | ViewDNS.info | MxToolbox | nslookup.io | Google Admin Toolbox Dig |
|---|---|---|---|---|---|
| Automatically converts the IP address you type into its reverse-lookup (PTR) query — no manual in-addr.arpa/ip6.arpa typing | ✓ | ✓ | ✓ | ✓ | ✗ |
| Shows the full PTR hostname with no sign-in | ✓ | ✗ | — | — | ✓ |
| Supports IPv6 reverse (PTR) lookups, not just IPv4 | ✓ | — | — | — | — |
| Documents its own API for reverse DNS lookups | ✗ | ✓ | — | ✓ | — |
| Free to run, no account required | ✓ | ✓ | ✓ | ✓ | ✓ |
| Part of a much wider general-purpose tool suite, not a single-purpose reverse DNS tool | — | ~25 tools + API (own page) | Free DNS/email suite + 100+ blacklists, operating since 2004 (own page) | 20+ tools across DNS, certificates, email/security and IP (own page nav) | Small diagnostic toolbox: Browserinfo, Check MX, Dig, HAR/Log Analyzer, Messageheader, Useragent (own page nav) |
AdminKit vs ViewDNS.info
Automatically converts the IP address you type into its reverse-lookup (PTR) query — no manual in-addr.arpa/ip6.arpa typing
Shows the full PTR hostname with no sign-in
Supports IPv6 reverse (PTR) lookups, not just IPv4
Documents its own API for reverse DNS lookups
Part of a much wider general-purpose tool suite, not a single-purpose reverse DNS tool
AdminKit vs MxToolbox
Automatically converts the IP address you type into its reverse-lookup (PTR) query — no manual in-addr.arpa/ip6.arpa typing
Shows the full PTR hostname with no sign-in
Supports IPv6 reverse (PTR) lookups, not just IPv4
Documents its own API for reverse DNS lookups
Part of a much wider general-purpose tool suite, not a single-purpose reverse DNS tool
AdminKit vs nslookup.io
Automatically converts the IP address you type into its reverse-lookup (PTR) query — no manual in-addr.arpa/ip6.arpa typing
Shows the full PTR hostname with no sign-in
Supports IPv6 reverse (PTR) lookups, not just IPv4
Documents its own API for reverse DNS lookups
Part of a much wider general-purpose tool suite, not a single-purpose reverse DNS tool
AdminKit vs Google Admin Toolbox Dig
Automatically converts the IP address you type into its reverse-lookup (PTR) query — no manual in-addr.arpa/ip6.arpa typing
Shows the full PTR hostname with no sign-in
Supports IPv6 reverse (PTR) lookups, not just IPv4
Documents its own API for reverse DNS lookups
Part of a much wider general-purpose tool suite, not a single-purpose reverse DNS tool
Last checked
Sources: ViewDNS.info — Reverse DNS Lookup, ViewDNS.info — Reverse DNS Lookup result for 8.8.8.8 (masked result, verified 2026-10-29), MxToolbox — Reverse Lookup, nslookup.io — PTR Lookup, Google Admin Toolbox — Dig, RFC 1035 — Domain Names: Implementation and Specification (PTR records, in-addr.arpa), RFC 3596 — DNS Extensions to Support IP Version 6 (ip6.arpa)
Frequently asked questions
Why doesn't this comparison include dnschecker.org's reverse DNS lookup tool?
Every read-only GET of dnschecker.org's own reverse DNS lookup page on 2026-11-04 — tried with both a standard browser user-agent and a separate fetch tool — returned an HTTP 403 response instead of the page itself, consistent with an automated-access block. Rather than describe its features from memory, it was left out of this comparison entirely instead of citing anything unverified.
AdminKit already has a page comparing it to ViewDNS.info directly — why a second comparison?
The two pages answer different questions. AdminKit vs ViewDNS.info: reverse DNS (PTR) lookup is a one-on-one deep dive into that single competitor, including a live test showing ViewDNS.info masks the PTR result behind a sign-in prompt. This page is the wider category roundup: how AdminKit's reverse DNS tool stacks up against ViewDNS.info, MxToolbox, nslookup.io and Google Admin Toolbox Dig side by side. The masking fact is reused here with its original 2026-10-29 verification date rather than re-tested, and nothing here is claimed in more detail than the head-to-head page already covers.
Does Google Admin Toolbox Dig do a reverse DNS lookup the same way as the others?
No, and this page doesn't claim it does. ViewDNS.info, MxToolbox and nslookup.io each accept a plain IP address and automatically build the reverse-lookup query for you, per their own pages. Google Admin Toolbox Dig's own page instead offers PTR as one of many raw DNS record-type buttons (alongside A, AAAA, MX, NS and others) next to a plain text field — to look up a PTR record there, you have to type the full reverse name yourself (for example 8.8.8.8.in-addr.arpa), the same way you would with the command-line dig tool.
Do MxToolbox, nslookup.io or Google Admin Toolbox Dig support IPv6 reverse lookups?
Unverified for all three. None of their own pages checked for this comparison state either way whether IPv6 (ip6.arpa) reverse lookups are supported — nslookup.io's PTR tool page only shows IPv4 worked examples, and MxToolbox's and Google Admin Toolbox Dig's pages don't address IP version at all. Rather than assume, this page marks that point unverified. AdminKit's reverse DNS tool supports both IPv4 (in-addr.arpa) and IPv6 (ip6.arpa) per RFC 1035 and RFC 3596.
Is this page ranking these tools from best to worst?
No. An account-free hostname lookup, a tool bundled into a much larger DNS/email suite, and a raw DNS query tool that happens to support the PTR record type all solve different problems, so a single best-to-worst order would misrepresent what each is for. The table below states only what each tool's own page confirms (or marks unverified honestly when it doesn't), so you can match the tool to what you actually need.
Does this page use ViewDNS.info's, MxToolbox's, nslookup.io's or Google's logo or brand assets?
No. All four names are used only to identify and compare publicly available services (nominative use). AdminKit is not affiliated with or endorsed by ViewDNS.info, MxToolbox, Inc., nslookup.io, or Google LLC.
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