Free email & network tools

The tools we kept reaching for while building an email service, now running in your browser — with the few that genuinely need a server (SMTP, IP checks) running from ours. Nothing you paste is uploaded anywhere; there is no account and no tracking around them.

• Email header analyzer — paste any email source: SPF/DKIM/DMARC verdicts, the full Received-chain delivery path and header-by-header inspection.
• MIME decoder — turn raw RFC 822 into readable parts: quoted-printable and base64 decoded, encoded-word subjects unwrapped, attachments listed with sizes.
• Email HTML preview — render email HTML in a sandboxed frame at desktop or mobile width, plus an auto-generated plain-text version.
• Email validator — bulk syntax checks with clear reasons, typo suggestions, and optional live MX lookups per domain.
• Email regex tester — test any email-matching regex against real-world edge cases, with HTML5, pragmatic and RFC 5322 presets.
• SMTP tester — run a real SMTP conversation from Tempx's servers: full EHLO/STARTTLS/AUTH/MAIL/RCPT/DATA transcript with per-step timing.
• My IP & network check — your connection as Cloudflare's edge sees it: country, city, timezone, datacenter (colo), ASN and TLS details, plus proxy/VPN/Tor/hosting intelligence and spam reputation for any IP.

Doing this often? Tempx for Developers shows how to give every test run its own disposable inbox — and the tools above work on whatever lands in it.