Free · open source · no account · works in Chrome and Firefox
Highlight a domain.
Know everything about it.
Extend.Domains puts registration, DNS, parking status, site preview, archive history and a quality score in a sidebar — for any name you select on any page. No tab switching, no WHOIS site, no account, no API keys.
Notes on naming things
Every spec I have read this month points the reader at when it needs a placeholder, which is exactly the problem with placeholders.
Extend.Domains
Highlight a domain name on any page, then open the lookup from the right-click menu or the toolbar button.
example.com — A registered, delegated name: registry record, live nameservers, and a site that answers.
Illustrative sample data. The real panel fetches this live from public registry, DNS, and archive endpoints.
Checking a name used to cost you five tabs
A WHOIS site for the registration. A DNS tool for the records. The domain itself, to see whether anything answers. A parking check, because half the “live” names are sale landers. An archive lookup, because a 2011 creation date means nothing if the name was first seen in 1998.
Every one of those is a public, keyless endpoint. The extension asks all of them at once, from the background, and lays the answers out in one panel next to the page you were already reading.
- 0
- servers of ours in the path
- 0
- API keys to sign up for
- 0
- trackers or analytics
- 24 h
- local cache per domain
What lands in the panel
Every card is a separate source. None of them blocks another, and any one of them can fail without taking the panel down with it.
Registration, from the registry
Created, expires, last updated, registrar and IANA id, EPP status codes, DNSSEC — read over RDAP straight from the registry that runs the TLD. No registrant fields: those are redacted post-GDPR everywhere, and pretending otherwise would be a lie.
DNS at a glance
NS, A, MX and TXT over DNS-over-HTTPS, plus the signals derived from them: delegated or not, whether the name can receive email at all, SPF and DMARC present or missing.
Parked, or actually used
Nameserver patterns for Afternic, Sedo, Bodis, Dan, Above.com, ParkingCrew, Atom and others are matched by name, so you know a domain is sitting on a broker's sale page before you write the acquisition email.
Availability, stated honestly
An authoritative 404 from the registry means unregistered. Anything else — a timeout, a 500, a rate limit — is reported as unknown. The panel never upgrades a failure into “available”.
A local quality score
Six signals — length, dictionary-word coverage, pronounceability, hyphen and digit composition, TLD, and short-pattern bonus — computed on your machine, with the per-component breakdown shown so you can see why the number is what it is.
What the site actually says
Title, description, og:image and theme colour parsed from the first 32 KB of the domain root — with a warning when that root redirects to a different registrable domain.
Real age, not registration age
The first Wayback Machine snapshot, linked. When the archive predates the current registration date, the panel says so: the name had a previous life before whoever holds it now.
Lookalike characters, flagged
Mixed-script names and Cyrillic or Greek homographs are detected and painted red, and punycode is decoded so an xn-- form is shown as the text it renders as.
Research links that go somewhere
Appraisal, sale comps, cross-TLD usage, UDRP dispute history and trademark search — eleven tools, six on by default, each its own checkbox. Plain nominative links, no logos and no referral codes.
For-sale names, one click from the listing
When a name's nameservers show it is listed on Atom.com, the panel offers a Buy now button. That link carries an affiliate referral code — the only monetised link in the extension — and it switches off in the settings.
Three moves, then read
The panel opens on a click you make — browsers only allow it that way — and then keeps up with you on its own.
- 1
Highlight the name
Anywhere text lives: a forum thread, a spreadsheet, a chat message, an email, a code comment. - 2
Open the panel
Right-click → Look up “…”, the toolbar button, or the keyboard shortcut. Once it is open, highlighting another name updates it live — no second click. - 3
Read it as it fills
The name, the score and the research links are there instantly, computed locally. Registry, DNS, site preview and archive land independently, each as soon as it answers.
How it is wired
content script detects the selection
│ (regex pre-gate, ~3 kB)
▼
background all network fetches
│ cache · rate limit
▼
sidebar panel renders progressivelyNo fetch ever originates from the page you are reading or from the panel itself. The content script on a page carries a small regex and nothing else — the full public suffix table, the network calls and the cache all live in the extension’s background context, loaded once per browser rather than once per tab.
Results are cached in local storage for 24 hours per domain, so looking the same name up twice costs zero requests.
Where the data comes fromThen bend it to your workflow
The settings page is not a token two-checkbox affair — every card, every scoring weight and every detection rule is yours to change, and an open panel re-renders the moment you save.
Reorder and hide cards
Drag the eight sidebar blocks into the order you actually read them in, and switch off the ones you never do.
Pick your registrar
Thirteen registrars; the register button on an available name deep-links into the one you chose.
Tune the score
Every weight, curve and per-TLD value is editable, with a live “try it” box that scores a name against your unsaved edits.
Catch dodged links
Opt in to resolving example dot com, example[.]com and example (dot) com — off by default, and it costs nothing when off.
Choose your research tools
Eleven appraisal, comps, trademark and backlink tools, each with its own checkbox, and a reset button when you have gone too far.
Switch off the Buy now button
The one affiliate link in the extension is a checkbox away from never appearing. Turning it off changes nothing else.
Suggest a feature, report a bug
A missing registry, a TLD that renders wrong, a scoring weight that feels off, a card you wish existed — all of it is welcome. Write to info@extenddomains.com, or open an issue if you would rather it be public.
Stop opening five tabs to check one name
It is free, it has no upsell, and the whole thing is on GitHub.