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CaptainDNS

Propagation & diagnostics

Compare resolvers worldwide and inspect returned answers.

Email authentication

Tools to verify and validate your email authentication setup.

SPF syntax validator

Review include chains and DNS query limits before publishing changes.

SPF record inspector

Resolve the published TXT record, flag lookup limits and decode each mechanism.

DKIM syntax validator

Quickly check the syntax of your DKIM records.

DKIM record check

Resolve a selector and analyse the published DKIM TXT record.

DMARC syntax validator

Check rua/ruf destinations, alignment modes and the active policy before publishing.

DMARC record inspector

Resolve the published policy, surface diagnostics and confirm enforcement before switching to reject.

BIMI syntax validator

Validate BIMI tags, the logo fetch and the VMC certificate before publishing.

BIMI record inspector

Resolve the published BIMI record, inspect logo and VMC diagnostics in one place.

Email deliverability audit

Audit MX, SPF, DKIM and DMARC to confirm a domain is ready to send.

Mail header analyzer

Decode participants, authentication results and routing from raw headers.

DMARC record generator

Create compliant DMARC records with all policy and reporting options.

Text

Transform, encode and measure your content in seconds.

Text case converter

Convert any block of text to upper or lower case instantly.

Base64 encoder / decoder

Encode or decode any content in Base64 without leaving the browser.

Slug generator

Transform any sentence into an SEO-friendly slug in seconds.

Word & character counter

Measure the length of any text, with instant word and character counts.

Images

Preview and validate your BIMI logos before publishing.

BIMI logo lookup

Inspect a BIMI logo URL—format, metadata and live rendering—before rollout.

Certificates

Inspect CSRs, BIMI logos and VMC certificates before you deploy.

CSR parser

Inspect a CSR, extract subject details, fingerprints and requested SANs.

VMC inspector

Inspect a Verified Mark Certificate—issuer, validity and SAN coverage—before you publish BIMI.

IP

Look up addresses, owners, reverse records and ranges.

Reverse lookup

Resolve a PTR record and validate DNS consistency.

IP WhoIs

Identify the owner of an IP range and its contacts.

IPv4 netmask

Calculate network, broadcast and usable hosts for any IPv4 block.

My IP address

Detect your IPv4/IPv6 addresses and their geolocation.

Word & character counter

Why use this counter?

Count words, characters with or without spaces, lines and paragraphs with one click. Handy for framing a title, meta-description, tweet or SMS. The result helps you respect common limits without guessing.

How to use

  1. Paste or type your text in the area.
  2. Click Count words and characters.
  3. Read the displayed totals then copy what you need.

Tip Select a passage first to count only a portion of the text.

Quick use cases

  • Check the length of a meta title or meta description.
  • Adjust an email subject or push notification without cutting it off.
  • Respect the limit of a tweet or SMS.
  • Follow a word budget for a note or product sheet.

Important notes

  • Emojis or certain combined characters may count as multiple units depending on systems.
  • HTML formatting is not counted as readable text if you paste raw code.
  • Non-breaking spaces and line breaks affect totals. Clean up if needed.
  • Avoid pasting sensitive information. Keep a local copy if the text is critical.

Privacy commitment

The service sends your input to the CaptainDNS API which calculates only aggregated totals. The original text is not retained and only standard operational metrics are logged.