Free email tools

Five tools we kept reaching for while building an email service, now running entirely in your browser. Nothing you paste is uploaded anywhere — the analysis, decoding and rendering all happen locally; 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.

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