Domain list cleaner: strip URLs, dedupe, lowercase and validate a list of domains
In short: Paste domains, URLs or email addresses and get a clean, de-duplicated, lowercase list with accents converted to Punycode, and every invalid entry explained. Limit: It checks syntax only; it doesn't look the name up or check that the extension exists.
A domain list cleaner turns a messy paste into a clean list. It removes https://, paths, query strings, ports and a trailing dot, keeps the domain after an @, lowercases, optionally drops www. and subdomains, converts accented names to Punycode (xn--), removes duplicates and flags entries that aren't valid domain names, with the reason. It checks syntax only and runs in your browser.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. Check your list free nowSee pricing
Sample result
Six example entries become 4 clean names; 1 duplicate and 1 invalid (an underscore) are marked.
- Clean names
- 4
- Duplicates
- 1
- Entries read
- 6
What this means for you
A clean list is the start; whether a name is registered or reachable is another check.
- Strips URL, path, port, www
- Accents become Punycode
- Dedupes after cleaning
- Each invalid entry explained
- Domains
- Dedupe
- Validate
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
How do I clean and validate a list of domains?
- Paste domains, URLs or email addresses, separated by new lines, commas or spaces.
- Choose whether to remove www. and whether to cut subdomains (blog.acme.com becomes acme.com).
- Press Clean the list. Each entry is marked Already clean, Cleaned, Duplicate or Invalid, with what was changed or why it was dropped.
- Copy the clean names or download the CSV with the input, the result and the notes.
Example
- You enter
- Six entries:
https://www.Acme.com/pricing?utm=x,jane@globex.net,acme.com,bücher.example,shop_one.exampleandHTTP://blog.initech.co.uk:8080/. - You get
- 4 clean names: acme.com, globex.net, xn--bcher-kva.example and blog.initech.co.uk. 1 Duplicate (the second acme.com) and 1 Invalid (shop_one.example has an underscore).
- Limits
- Runs in your browser; nothing is uploaded. It checks syntax only, with www. removed by default.
How do I clean a list of domains?
Paste the list as it is. For each entry the tool removes the web address prefix, the path, the query string and the port, keeps only the part after an @ in an email address, drops a trailing dot, lowercases the name and, if you ask, removes www. and cuts subdomains. Names with accents or other scripts are written in Punycode, the xn-- form that DNS and registrars use.
Duplicates are removed after cleaning, so https://www.Acme.com/pricing and acme.com are the same entry. The first one stays and the rest are marked Duplicate. To pull domains out of a column of website URLs in a file, the extract domain from URL tool is built for that; this tool is for a mixed paste.
What makes a domain name invalid?
The tool applies the syntax rules of RFC 1035 and RFC 1123: parts made of letters, digits and hyphens; each part 1 to 63 characters; 253 in all; no part starting or ending with a hyphen; and an extension that is not all digits. It also flags an underscore, which is valid in some DNS record names but not in a domain name, and -- in the third and fourth positions of a name that isn't an xn-- name.
It checks the shape of the name, not the name itself. It does not look it up, and it does not check that the extension exists, so a tidy name here can still be unregistered. To see which are free, use the bulk domain availability checker.
What does cutting subdomains do?
It reduces blog.acme.com to acme.com so a list of hosts becomes a list of companies. To find the name part it uses a short list of two-part suffixes such as co.uk and com.au; it is not the full Public Suffix List, so a name under a less common two-part suffix can be cut in the wrong place. Check anything unusual by eye.
Leave it off if the subdomain matters, for example when you are auditing mail hosts or tracking domains, where track.acme.com and acme.com are different things.
Who uses this tool, and for what?
- Sales operations
- Turn a mixed paste of websites and email addresses into one clean list of company domains before enrichment.
- Cold emailers
- Dedupe the sending domains you own across several exports before auditing their DNS.
- IT and domain administrators
- Tidy a portfolio list from several registrars into one lowercase, de-duplicated list.
What can’t this tool tell you?
- It checks syntax only; it doesn't look the name up or check that the extension exists.
- Subdomains are cut using a short list of two-part suffixes, not the full Public Suffix List.
- Punycode conversion covers ordinary names; a registry can still refuse a name that converts.
- A domain valid here can still be unregistered or unreachable.
Common questions
- How do I remove https and www from a list of domains?
- Paste the list here and press Clean the list. The web address prefix is always removed, and www. is removed unless you untick the option.
- Is this domain list cleaner free?
- Yes. It is a free tool and runs in your browser, with no account and no card.
- How does it deal with accented domain names?
- It writes them as Punycode, so bücher.example becomes xn--bcher-kva.example. Use the Punycode converter to read a name both ways.
- Does it check that the domains exist?
- No. It checks the syntax of each name only. A valid name may be unregistered; use the bulk domain availability checker to see which are registered.
- What happens to email addresses?
- The part after the @ is kept, so jane@globex.net becomes globex.net. The address itself is not checked.
- Is my list uploaded?
- No. The list is read in your browser and goes nowhere.
Sources
Authentication and capacity are half of deliverability.
The other half is who you send to. Every hard bounce counts against the domain and inboxes you are sending from, and nothing in DNS can tell you which addresses on your list are dead.
- Bulk verification with real SMTP mailbox checks
- Hard bounces removed before a send, not discovered after
- Catch-all, disposable and role detection on every row
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.