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web validator

Domain Validator

Validate domain names with proper labels and TLDs—client-side only.

Results

Paste input and validate locally.
Status
Ready when you validate.
Details
Ready when you validate.

How to use this validator

  1. Paste the domain.
  2. Run validate to check labels and TLD.
  3. If invalid, remove underscores/invalid chars and ensure a TLD is present, then re-run.

Rules & checks

Requires a valid TLD and label structure.

Blocks underscores and invalid characters.

Does not resolve DNS—format-only.

Inputs explained

  • Domain

    Enter a full domain like example.com or sub.example.co.uk. Lowercase is recommended.

When to use it

  • Validate domains in signup or lead forms
  • Check domains before configuring SSL or DNS records
  • Verify partner domains in integrations

Common errors

  • Missing TLD or trailing dot
  • Underscores or invalid characters in labels
  • Leading/trailing hyphens in a label

Limitations

  • Format-only; does not resolve DNS, check availability, WHOIS, or ownership.
  • IDN/punycode is not converted here; use punycode-aware validation if you need full internationalized domain support.
  • Does not confirm live MX/HTTPS/CAA/NS records—pair with MX/SPF/DKIM/DMARC/CAA validators.
  • No URL parsing here—supply bare domains; use the URL validator for full URLs.

Tips

  • Require https URLs separately if you need protocol checks
  • Keep domains lowercase to avoid confusion
  • Trim whitespace before validation

Examples

Valid domain

  • example.com -> Valid

Valid subdomain

  • cdn.example.co.uk -> Valid

Invalid (no TLD)

  • example_local -> Invalid (missing TLD)

Invalid chars

  • exa_mple.com -> Invalid (underscore not allowed)

Deep dive

This domain validator checks label/TLD format client-side, blocking underscores, leading/trailing hyphens, and missing TLDs without doing DNS lookups.

Use it to clean domains in forms and configs before hitting your backend, then layer DNS checks (MX/SPF/DKIM/DMARC) if needed.

FAQs

Do you check DNS or availability?
No. This validates format only; it doesn’t resolve DNS or WHOIS.
Can subdomains be used?
Yes, as long as they include a valid TLD and conform to label rules.
Is anything stored?
No. Validation runs locally and clears on refresh.
Do you handle IDN domains?
This is ASCII-focused. Convert IDNs to punycode first if needed.
Why did my domain fail?
Common reasons: missing TLD, underscores, leading/trailing hyphens, or invalid characters.

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