DNS Lookup
Choose a DNS record type to search for.
Propagation & diagnostics
Compare resolvers worldwide and inspect returned answers.
Keep history, monitor your zones and automate recurring checks.
Email authentication
Tools to verify and validate your email authentication setup.
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.
Certificates
Inspect CSRs, BIMI logos and VMC certificates before you deploy.
IP
Look up addresses, owners, reverse records and ranges.
Resolve, audit and fix DNS, SPF, DKIM and DMARC records from a single dashboard built for deliverability teams and SRE engineers.
Aggregated data since 2025
Three modules at the heart of CaptainDNS to troubleshoot zones, secure authentication and keep campaigns out of spam folders.
Instant A, AAAA, MX, TXT and CNAME resolutions across 18 resolvers with latency and RCODE insights.
Start a lookupFull SPF, DKIM, DMARC, MX, TLS, PTR and DNSSEC analysis for every sending domain you manage.
Audit a domainHardened parsers, policy suggestions and lookup budgeting to prevent blocks and maximise alignment.
Explore analyzersCombine DNS diagnostics, authentication checks and automation to keep your campaigns in the inbox.
Compare UDP, TCP and DoH answers, monitor latency and export every iteration.
SPF, DKIM, DMARC, MX, TLS and PTR checklist with automatic prioritisation.
Advanced syntax analysis, visual include tree and DNS lookup budgeting.
Validate tags, simulate policy impact and get recommendations to move into enforcement.
Plug CaptainDNS into your CI/CD, export reports and trigger incident alerts automatically.
CaptainDNS · October 29, 2025
DMARCbis replaces RFC 7489, drops the PSL in favor of a DNS Tree Walk, adds 'psd', 'np' and 't', removes 'pct', 'ri' and 'rf', and splits reporting into two documents. Here's what it means...
CaptainDNS · October 23, 2025
ARC (Authenticated Received Chain) lets every relay forward, sign, and seal the authentication results it observed so the final server can decide whether to trust the message.
CaptainDNS · October 22, 2025
AI-automated phishing emails average a click-through rate of roughly 54%. At scale, automation can make these campaigns up to ×50 more profitable. Both figures come from the Microsoft Digital Defense Report 2025 (MDDR 2025).
We build CaptainDNS to give marketing and SRE teams complete visibility into DNS configuration and deliverability signals. Every tool explains what must be fixed and why it matters.
Our distributed infrastructure mirrors the reality of your recipients. Know whether resolvers in Frankfurt, Sydney or Montreal see the same answer, and get alerted as soon as a divergence appears.
Stay in control of DNS and deliverability with actionable explanations. Here are the answers to the most common requests.
Try it for free, then upgrade to the plan that matches your volume when you're ready.