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112 free tools

Free DNS, email and domain tools

Check a record, generate one, or do the maths. Free, with no account, and every answer says where its figures come from.

Email authentication

Check and build the SPF, DKIM and DMARC records that decide whether mail arrives.

  • SPF checker

    Check an SPF record for the faults that silently break it, and count every DNS lookup it costs.

    Live check

  • SPF record generator

    Build a valid SPF record from the senders you actually use, and see the DNS-lookup cost before you publish it.

    In your browser

  • DKIM checker

    Find a domain’s DKIM key, read its tags in plain words, and flag a weak, revoked or malformed one.

    Live check

  • DMARC checker

    Read a DMARC record in plain words, and see exactly what a receiver does with mail that fails.

    Live check

  • DMARC record generator

    Build a DMARC record step by step, from monitoring through to full enforcement.

    In your browser

  • Email authentication report

    See SPF, DKIM, DMARC and MX for one domain together, with the fixes in the order to do them.

    Live check

  • Google Workspace setup checker

    Check a domain’s MX, SPF and DKIM against the exact values Google Workspace documents.

    Live check

  • Microsoft 365 setup checker

    Check a domain’s Microsoft 365 SPF include and both DKIM selector CNAMEs, mistake by mistake.

    Live check

  • Fastmail setup checker

    Compare a domain’s MX, SPF and all three DKIM CNAMEs with the exact values Fastmail documents.

    Live check

  • Zoho Mail setup checker

    Confirm the SPF include Zoho documents, the zoho DKIM selector and Zoho’s mail hosts for a domain.

    Live check

  • SPF flattening explainer

    See how many of a domain’s SPF lookups flattening would actually remove, and what it costs to keep one flattened.

    Live check

  • SPF record parser

    Paste a draft SPF record and read it term by term, with the faults named, before anything is published.

    In your browser

  • DMARC record parser

    Paste a DMARC record you are drafting and read every tag in it, with the syntax a receiver would discard it for.

    In your browser

  • Authentication-Results header explainer

    Paste the Authentication-Results line off a message and read what every verdict in it means, including Microsoft’s compauth result and its three-digit reason code.

    In your browser

  • Email header analyser

    Paste a raw email header block and read every Received hop, its delay and every SPF, DKIM and DMARC verdict in plain words.

    In your browser

  • DKIM key generator

    Generate a DKIM keypair in your own browser and get the record to publish.

    In your browser

  • DMARC aggregate report reader

    Read the RUA XML your mailbox provider emailed you by source IP, in this tab, without uploading it.

    In your browser

  • MTA-STS checker

    Read a domain’s MTA-STS record and policy file, and check every mx pattern against its live MX records.

    Live check

  • MTA-STS record and policy generator

    Write both halves of MTA-STS at once: the _mta-sts TXT record and the policy file.

    In your browser

  • TLS-RPT record generator

    Build the _smtp._tls record that asks senders to report failed TLS to your mail hosts.

    In your browser

  • BIMI checker

    Read a domain’s BIMI record, check the SVG logo against Tiny PS, and whether DMARC lets it count.

    Live check

  • BIMI record generator

    Build the BIMI TXT record for your logo, with or without a certificate.

    In your browser

DNS

Read what a domain is really publishing, and build the records a provider asks for.

  • MX lookup

    See where a domain receives mail, in priority order, with the faults that stop it.

    Live check

  • DNS lookup

    Query any DNS record type from two resolvers at once, so a change still spreading is easy to spot.

    Live check

  • DNS propagation checker

    See whether a DNS change has reached two independent public resolvers yet, with their TTLs.

    Live check

  • Nameserver and DNS host checker

    See who hosts a domain’s DNS from its nameservers, and whether the registry’s own list still matches what the zone answers.

    Live check

  • DNS record type explainer

    Nine DNS record types explained in plain words, each with a worked example - and, add a domain, the chosen type looked up live through two resolvers.

    Live check

  • DNS change verifier

    Get a plain pass or fail on whether the value you just set has actually taken effect.

    Live check

  • CNAME chain follower

    Follow a CNAME chain hop by hop to its final address, and catch a loop or a dead end before anything fetches it.

    Live check

  • CAA record checker

    Read which certificate authorities a domain allows, and see whether the one you actually use is among them.

    Live check

  • CAA record generator

    Build a CAA record that names exactly the certificate authorities allowed to issue for a domain, wildcards and all.

    In your browser

  • Apex CNAME checker

    See whether a name is really its own zone apex, and whether a CNAME sitting there is legal or just flattened.

    Live check

  • SOA record checker

    Read a zone’s SOA record as seven plain-English timers, and catch a serial or a refresh that will cause real trouble.

    Live check

  • DNSSEC chain checker

    See whether a domain publishes a DS record that actually matches its own DNSKEY, recomputed by hand rather than taken on trust.

    Live check

  • Zone file checker

    Paste a BIND-style zone file, or point this at a live domain, to catch a CNAME sharing a name it should not and an SOA whose timers are ordered wrong.

    Live check

  • TTL migration planner

    When to drop a TTL before a DNS cutover, and the first moment the old value is actually gone.

    In your browser

  • Subdomain takeover checker

    Follow a subdomain's CNAME to its target and say whether that target looks abandoned enough for someone else to claim.

    Live check

  • IP-to-ASN and network lookup

    Look up which autonomous system and network an IP address belongs to, and who that network is registered to.

    Live check

  • SRV record generator & checker

    Build a correctly shaped SRV record for SIP or Microsoft Teams, then check the live one against it for exactly what a registrar panel tends to mangle.

    Live check

  • DNS health report

    See DNSSEC, CAA and the nameservers for one domain together, with the fixes in the order to do them.

    Live check

  • Zoho Mail DNS record generator

    Get the three MX records and the SPF include Zoho Mail needs, ready to paste into any DNS panel.

    In your browser

  • Fastmail DNS record generator

    Get every DNS record a Fastmail custom domain needs - MX, SPF and all three DKIM CNAMEs - with nothing left as a placeholder.

    In your browser

  • Google Workspace DNS record generator

    Get the one MX record and SPF include Google Workspace documents, and a plain answer about the old "aspmx" records.

    In your browser

  • Microsoft 365 DNS record generator

    Get the handful of DNS records Microsoft 365 documents as fixed for every tenant, and a plain list of the ones only your own admin center can give you.

    In your browser

  • Shopify DNS record generator

    Get the apex A record, the AAAA record and the www CNAME Shopify asks for, with its own one-record-only rule flagged before you publish.

    In your browser

  • GitHub Pages DNS record generator

    Get the four fixed apex A records, the optional IPv6 set and the www CNAME GitHub Pages needs, with your own user or organisation name built in.

    In your browser

  • Squarespace DNS record generator

    Get the four apex A records and the www CNAME Squarespace needs for a custom domain, ready to paste into any DNS panel.

    In your browser

  • Netlify DNS record generator

    Get Netlify's apex record - ALIAS, ANAME or the fallback A - plus a www CNAME completed with your own Netlify subdomain.

    In your browser

  • TXT record splitter

    Split a long TXT record value into properly quoted 255-byte character-strings, or the one value a panel that auto-joins would want.

    In your browser

Domains

See whether a name is free, who holds it, and what the registry says about it.

  • Domain availability checker

    Check whether a name is registered at the registry, across endings or a whole list at once.

    Live check

  • WHOIS / RDAP lookup

    See a domain’s registrar, its dates and every status code explained, read from RDAP rather than old WHOIS.

    Live check

  • Domain name generator

    Build names from your own words and see which ones the registry has no record of yet.

    Live check

  • Domain ending explorer

    See who runs each domain ending, when it was delegated and who it suits - then check your name on it.

    Live check

  • Domain portfolio expiry checker

    Paste up to 20 domains and get the registrar, expiry date, status and days left for every one.

    Live check

  • Domain portfolio renewal calendar

    Paste the domains and dates you already have, see them sorted and grouped by month, and download the whole lot as a calendar file.

    In your browser

  • Domain renewal and transfer cost planner

    Project several years of renewals across a portfolio, with the increase you expect compounding, and see which names cannot be transferred yet.

    In your browser

  • Typo and lookalike domain finder

    Generate the lookalikes of your domain and see which are already registered or resolving.

    Live check

  • Domain age and registrar checker

    See how old a domain is by its registry registration date, and which registrar holds it.

    Live check

  • EPP status code list explainer

    Paste a column of domain status codes from any export and read what every one of them means, with no lookup.

    In your browser

  • Domain naming rules checker

    Check a candidate name against the rule every ending shares, and then against that registry’s own stricter one.

    In your browser

  • Redirect chain checker

    Follow a URL hop by hop and see the status, the target and the headers of each one.

    Live check

Deliverability

Meet the rules the big mailbox providers set before they start rejecting your mail.

  • Bulk sender requirements checker

    Check one domain against Google's and Yahoo's own published bulk-sender rules, with what neither can see named outright.

    Live check

  • Reverse DNS checker

    Look up the PTR record for an IP address, and see what it is worth fixing for mail.

    Live check

  • FCrDNS checker

    Run the real two-hop forward-confirmed reverse DNS check on an IP address, not just the PTR half.

    Live check

  • Provider sending limit checker

    See Google Workspace's and Microsoft 365's own published sending limits side by side, each cited to the vendor's own page.

    In your browser

  • List-Unsubscribe header checker

    Paste raw headers and see whether List-Unsubscribe and List-Unsubscribe-Post pass RFC 8058's one-click unsubscribe syntax, with no request ever sent to the link inside.

    In your browser

  • List-Unsubscribe header generator

    Build the List-Unsubscribe and List-Unsubscribe-Post headers RFC 8058 one-click unsubscribe needs from your link, or nothing at all when the link cannot carry a POST.

    In your browser

  • Tracking domain CNAME checker

    Follow a tracking subdomain’s CNAME chain and see whether it ends at a known ESP’s tracking host.

    Live check

  • Mailbox calculator for cold email

    How many mailboxes and domains a daily send target needs, once you say what one mailbox can safely carry.

    In your browser

  • Warm-up schedule planner

    A day-by-day ramp from a starting volume to a target, at whatever daily growth rate you choose to plan around.

    In your browser

  • Mailbox rotation planner

    Split today's send evenly across an existing mailbox pool, and flag any mailbox pushed past the safe figure you set.

    In your browser

  • Spam trigger word checker

    Check a subject and body against a fully shown list of urgency and money wording, all-caps words and repeated punctuation - grouped by category, nothing hidden.

    In your browser

  • Subject and preview text length tester

    Count a subject line and preview text against the character cut-offs email service providers have actually measured, by client.

    In your browser

  • SPF/DKIM/DMARC alignment checker

    Paste a message’s headers and see whether its DKIM signature and Return-Path actually align with the From: address the reader sees - strict and relaxed.

    In your browser

  • Gmail message size clipping checker

    Compare a message’s HTML, or a byte count you already have, against the ~102 KB estimate Mailchimp and Litmus each measured for Gmail clipping - never presented as Google’s own rule.

    In your browser

For developers

Try a webhook, a key or an API call without writing a script to do it first.

  • Webhook signature verifier

    Paste the three webhook headers, the raw body and the secret, and see whether the recomputed signature matches - and whether the timestamp is still inside the tolerance window.

    In your browser

  • Webhook replay window checker

    Decode a webhook-timestamp header into its exact UTC time and tolerance window, and check whether a clock reading falls inside or outside it.

    In your browser

  • Signing secret generator

    Make a whsec_ webhook signing secret shaped exactly like ours, with its .env line, for testing a local receiver before a real endpoint exists.

    In your browser

  • Standard Webhooks payload signer

    Type an id, a timestamp and a raw body, give a whsec_ secret, and get the exact webhook-id, webhook-timestamp and webhook-signature headers for it.

    In your browser

  • Webhook payload example generator

    Pick one of our documented events and get a sample payload, plus the signed headers a delivery of it would carry, ready to send to a local receiver.

    In your browser

  • Idempotency key generator

    Make a UUID v4 for the Idempotency-Key header, with a ready curl line and our own retry rules explained next to it.

    In your browser

  • API request builder

    Pick one of our documented operations and get a ready curl, Python or Node snippet, with the real base URL and an Idempotency-Key where the operation spends money.

    In your browser

  • Postman collection generator

    Get a full Postman Collection v2.1 JSON for our API, with the real base URL and a bearer-auth placeholder already set - paste it straight into Postman.

    In your browser

  • API error code explainer

    Type one of our documented error codes, a bare status, or paste a whole response body, and get the exact status, message, meaning and what to change in the request.

    In your browser

  • ULID / request id decoder

    Split one of our own prefixed ids, or a bare ULID, and read the exact UTC time it was minted - and say plainly when a prefix is not one of ours.

    In your browser

Messaging

Work out what a text message really costs to send.

Pricing and billing

Work out what to charge, what it leaves you, and what a change mid-cycle costs.

  • Markup vs margin calculator

    Turn a cost into a price or a price into a cost, and see markup and margin as the two different numbers they are.

    In your browser

  • Google Workspace vs Microsoft 365 cost comparison

    Both vendors’ list prices at the tier and seat count you pick, with the storage each seat actually gets for the same money.

    In your browser

  • Reseller profit planner

    Every product line you bill in a month, the fixed costs no single sale sees, and the client count it takes to cover them.

    In your browser

  • Seat cost planner

    Price a licence term seat by seat, put a figure on the seats nobody signs in to, and prorate a seat change that landed mid-cycle.

    In your browser

  • Reseller break-even calculator

    How many clients it takes to cover a month of fixed costs, rounded up, because clients come whole.

    In your browser

  • Proration calculator

    Work out what seats added or removed partway through a billing cycle are worth, to the cent, and check a vendor’s part-cycle line against it.

    In your browser

  • MRR to ARR calculator

    Turn recurring revenue into its yearly figure, then watch what new, expansion, churn and contraction do to it over the next twelve months.

    In your browser

  • Customer lifetime value calculator

    Work out what a customer is worth in profit rather than in revenue, and set it against what it cost to win them.

    In your browser

  • Renewal increase notice builder

    Turn an old price and a new one into a customer-ready notice that names the exact dollar and percentage change, whichever way it moved.

    In your browser

  • Invoice maker

    Build a real invoice PDF, right in your browser - no watermark, no limit, nothing uploaded.

    In your browser

  • Quote / proforma builder

    Build a real quote PDF with a validity date, right in your browser, then convert it to an invoice in one click.

    In your browser

  • Credit note maker

    Build a real credit note PDF that states plainly which invoice it reduces - right in your browser.

    In your browser

  • EU VAT number checker

    Check an EU VAT number against VIES itself, and see the registered trader name.

    Live check

  • Reverse charge VAT helper

    See whether to charge VAT or write “reverse charge,” checking the buyer’s VAT number live against VIES.

    Live check

  • Price list builder

    Apply one markup policy to a whole list of SKUs at once, and get a price list to copy or download.

    In your browser

  • Dunning schedule planner

    Turn one overdue invoice into the four reminder dates and reminder text to send for it.

    In your browser

  • VAT calculator

    Add, remove or work out VAT using whatever rate you type - confirmed against the official source, not a table baked into this page.

    In your browser

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