SSL Certificate Decoder (PEM)
Paste a PEM X.509 certificate to decode every field in your browser — subject, issuer, SANs, validity with days-left, key type and size, key usage, fingerprints and Certificate Transparency SCTs. Nothing is uploaded.
About SSL Certificate Decoder (PEM)
SSL Certificate Decoder parses a pasted PEM certificate completely in your browser — subject and issuer, SANs, validity dates with days remaining, key algorithm and size, key usage, SHA-256/SHA-1 fingerprints and Certificate Transparency SCTs. It is openssl x509 -text without installing OpenSSL, and nothing you paste ever leaves your device.
How to use SSL Certificate Decoder (PEM)
- 1Paste or type your input into the box above — a sample is pre-filled so you can try it instantly.
- 2Set any options on offer (mode, key, format) to match what you need.
- 3The result appears the moment you type — no button to press, no waiting.
- 4Click Copy to grab the output — SSL Certificate Decoder (PEM) keeps everything on your device.
Why use SSL Certificate Decoder (PEM)?
- ✓Checking which domains a certificate actually covers before deploying it
- ✓Reading certs extracted from Kubernetes secrets, load balancers or config repos
- ✓Verifying issuer, expiry and fingerprint when debugging a TLS handshake failure
- ✓100% free with no sign-up, no watermark and no usage limits
- ✓Runs entirely in your browser — your text and keys are never uploaded, stored or logged
- ✓Works offline once loaded, with instant results and one-click copy
Frequently asked questions
How do I view what's inside an SSL certificate?+
Paste the PEM block (-----BEGIN CERTIFICATE-----) into the decoder and every field is shown instantly: subject, issuer, validity window, subject alternative names, public key details, extensions and fingerprints. Bare Base64 or hex DER also works — the parser reads the raw ASN.1.
Is it safe to paste a production certificate here?+
Yes. A certificate is public by design — it is sent to every client in the TLS handshake — and this decoder additionally runs 100% client-side, so the PEM is never uploaded. Never paste private keys anywhere, though; this tool neither needs nor accepts them.
Is it free to use?+
Yes — completely free with no sign-up, no account and no usage limits. There is no paywall, so you can encode, decode and convert as much as you like.
Is my data private and secure?+
Yes. This tool runs entirely in your browser using client-side JavaScript — your input is never uploaded to a server, stored or logged. Once the page has loaded you can use it offline, which makes it safe for tokens, keys and confidential data.
Related Security tools
CSR Decoder (Certificate Signing Request)
Decode a PKCS#10 certificate signing request in your browser: subject DN, requested SANs, public key type and size, signature algorithm and attributes — verify a CSR before you send it to a CA.
● LiveASN.1 / DER Parser (X.509 Viewer)
Parse any DER or PEM structure — certificates, CSRs, keys, PKCS#7 — into an indented ASN.1 tree with tag names, decoded OIDs, strings, integers and byte offsets. Works from PEM, Base64 or hex.
● LiveCertificate Chain Viewer & Checker
Paste a fullchain.pem with several certificates to see the chain order, each subject → issuer link, key types and expiry — and catch broken or wrongly-ordered chains before they hit production.
● Live