About Core Web Utilities

Core Web Utilities is a free collection of online utilities for DNS, email deliverability, network diagnostics and everyday developer tasks. It began as a clean, modern replacement for Google’s retired “Dig” tool and has grown into a broader toolbox.

What we believe

• Free and open to everyone. No accounts, no sign-up, no paywalls, no ads.
• Private by design. Nothing you look up is written to a database or a file. Queries run in memory and results go straight back to your browser.
• Fast and focused. Each tool does one job well, with clean, readable output.

How it works

Every lookup is performed on our server and returned over HTTPS. DNS tools query public resolvers directly; network tools connect only to public, internet-routable hosts. We keep a small in-memory counter purely to prevent automated abuse — it is never persisted and disappears when the service restarts.

Explore the tools

Browse everything from the home page, or jump to popular tools: DNS Lookup, SPF Checker, DMARC Checker, SSL Certificate Checker and WHOIS Lookup.