Read any certificate — without handing it to a stranger's server.
Paste PEM or drop .cer / .crt / .pem / .der / .pfx / .csr / .key files. Expiry countdown, SANs, chain checks, hostname coverage and plain-English problem cards — decoded in your browser, never uploaded. That matters double for .pfx files, which contain your private key.
Drop certificate, key or CSR files here
.pem, .crt, .cer, .der, .pfx/.p12 (with password), .csr, .key — single certs or whole chains. Decoded in your browser; nothing is uploaded.
Choose file(s)What you get
Instant status
Valid, expiring or expired — with exact day counts and a hostname-coverage checker including wildcard rules.
Chain intelligence
Drops a whole chain? We order it leaf→root, verify every link and flag missing intermediates — the classic "works in Chrome, fails in the app" cause.
Problems, explained
SHA-1 signatures, weak keys, self-signed certs, 398-day limits — every finding links to a plain-English fix page.
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See what a .reg file actually does — and whether it looks safe to run.
File Identifier
Don't know what a file is? Drop it — we identify it by its bytes.