Domain, IP, email, URL or raw DNS record. We detect the input and run the right audit in under 3 seconds.
For the parts of your stack that need uptime, alerts and a real owner, not a one-off check.
Real-time rua/ruf reports, sender breakdowns and alerts when alignment breaks.
Continuous monitoring of your email security and deliverability. Get alerted whenever a score or DNS record changes enough to affect deliverability or security.
Multi-region uptime checks, consensus across 3 regions, status and alerts.
Public status pages tied to your monitors. Custom domain, incidents, subscribers, RSS.
Host 301/302 redirects with HTTPS and per-link analytics. No server to maintain.
All audit tools stay free. Pay only for monitoring, hosting or higher API limits.
For occasional audits and one-off checks.
For independents and freelancers securing 1 to 3 domains.
For small teams securing multiple domains day to day.
For businesses securing multiple domains in production.
For agencies and MSPs handling many client domains.
For large accounts with custom needs.
All paid plans include a 14-day free trial. No credit card required. Cancel anytime.
Compare all featuresPick a category. Each tool ships with a live output preview.
Deep dives on DMARC, DNSSEC, deliverability and modern email security.
CaptainDNS · June 17, 2026
Barracuda Email Gateway Defense is the cloud SEG for SMBs and MSPs (200,000+ customers). Complete guide: architecture, *.ess.barracudanetworks.com MX, SPF/DKIM/DMARC, DNS detection, the distinction with the ESG appliance (CVE-2023-2868) and a comparison with Mimecast/Proofpoint/Defender.
CaptainDNS · June 9, 2026
Everything about the CAA DNS record: syntax, issue/issuewild/iodef tags, critical flag, inheritance, RFC 8659 and 8657, multi-provider setup, and auditing.
CaptainDNS · June 8, 2026
The IETF is reclassifying ARC (RFC 8617) as "Historic." But deprecated on paper does not mean dead in practice: Apple, Google and Microsoft still require it. Here is what really changes and what you should do.
Everything you wanted to know before signing up.
All 60+ audit tools are free forever with no sign-up. Paid plans only apply for monitoring, hosted services or higher API limits.
Yes, you can upgrade or downgrade at any time. The change takes effect immediately, with prorated billing handled by Paddle.
Audits run on the fly and are not persisted unless you save them in your account. We keep aggregate counters only, no PII, no third-party trackers.
You are billed 12 months upfront but pay for only 10: 2 months free versus the monthly rate. Cancel anytime, unused months are refunded prorata.
Calls succeed up to a soft overage cap (billed as one-time charges via Paddle), then return 429. You can disable overage in your plan settings. Existing resources stay active.
Credit card (Visa, Mastercard, Amex), PayPal, Apple Pay and Google Pay via our billing partner Paddle. Enterprise contracts support wire transfer and SEPA.
We parse rua and ruf reports in real time, deduplicate senders, expose failures with actionable signals and alert you when alignment breaks. EU hosting, no resale.
Yes on Business and Enterprise. Okta, Google Workspace and Azure AD are supported out of the box; custom SAML on Enterprise. SCIM provisioning available on request.
18 resolvers, 4 continents