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 Diagnostics
Tools to verify and validate your email authentication setup.
Secure & Monitor
Record generators, policy hosting and continuous monitoring.
Generators
Network & Web
Network tools, web page analysis and certificates.
IP Tools
My IP address
Detect your IPv4/IPv6 addresses and their geolocation.
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.
IPv6 subnet calculator
Calculate IPv6 subnets, address ranges and reverse DNS entries.
Certificates & BIMI
BIMI logo lookup
Inspect a BIMI logo URL - format, metadata and live rendering - before rollout.
BIMI SVG converter
Convert any SVG to BIMI-compliant Tiny-PS format in seconds.
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.
Web
Page size checker
Check if your page exceeds Google's 2 MB crawl limit.
Phishing URL Checker
Check if a URL is flagged as phishing or malware by 4 threat intelligence sources.
HTTP Headers Viewer
Inspect the HTTP headers returned by a URL, with security headers annotated.
HSTS Test
Analyze a domain's HSTS policy and its status on the Chromium preload list.
Redirect Checker
Analyze HTTP redirect chains
Domain Redirect
Redirect your domains with automatic HTTPS and 301/302 redirects.
HTTP Uptime Monitor
Monitor your sites with scheduled HTTP checks and email alerts.
Status Pages
Publish a public status page grouping your HTTP monitors.
Developer Tools
Text utilities and tools for everyday dev work.
Text
Transform and measure your content in seconds.
Text case converter
Convert any block of text to upper or lower case instantly.
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.
Password generator
Generate strong random passwords and memorable passphrases instantly.
Developer
Encoding, hashing, regex and formatting for everyday dev work.
Base64 encoder / decoder
Encode or decode any content in Base64 without leaving the browser.
Hash Generator
Compute MD5, SHA-1, SHA-256 and SHA-512 hashes of any text.
URL encoder / decoder
Encode or decode text using percent-encoding (RFC 3986) right in your browser.
Regex Tester
Test a regular expression against text and visualize matches.
JSON / YAML Formatter
Format, validate and convert JSON and YAML in one click.
OAuth 2.0 authentication for email APIs and integrations.
2 articles
Microsoft is retiring Basic authentication for SMTP AUTH on Exchange Online. Revised timeline, 550 5.7.30 error, OAuth alternatives, HVE, Graph API, and step-by-step migration checklist.
How we connected Auth0 to our CaptainDNS MCP server: dedicated audiences, PRM, Resource Parameter Compatibility Profile, JWT validation, identity propagation into profiles and api_requests, with optional auth today and protected tools ready for later.