SSL Certificate Decoder
Decode PEM certificates and show details
SSL Certificate Decoder is a free online tool from BrowserUtils that decode pem certificates and show details. It runs entirely in your browser — your data never leaves your device. No account required.
SubjectCN=Example
IssuerCN=Example
Not Before2024-01-01 00:00:00 UTC
Not After2025-01-01 00:00:00 UTC
Serial Number01
Signature AlgorithmSHA256withRSA
Public Key AlgorithmRSA
Public Key Size~4208 bits
How to use SSL Certificate Decoder
- 1 Paste or type your input into the editor above.
- 2 The tool processes your data instantly — right in your browser, with nothing sent to a server.
- 3 Copy the result with one click or continue editing your input.
About SSL Certificate Decoder
Free online SSL certificate decoder. Paste a PEM-encoded certificate to view subject, issuer, validity dates, serial number, and other certificate details. This tool runs entirely in your browser — your data is never sent to a server. Just paste your input, get instant results, and copy with one click. No sign-up or installation required.
SSL Certificate Decoder specs
- Runtime
- 100% client-side (browser)
- Built on
- WHATWG URL API and Headers/Fetch standards as implemented by modern browsers
- Cost
- Free — no account, no rate limits, no usage caps
- Browser support
- Chrome 90+, Firefox 88+, Safari 14+, Edge 90+
- Part of
- 299 developer tools on BrowserUtils (100% client-side)
Questions
What is a PEM certificate?
A PEM (Privacy Enhanced Mail) certificate is a Base64-encoded file format for storing cryptographic certificates. It starts with -----BEGIN CERTIFICATE----- and ends with -----END CERTIFICATE-----. It is the most common format for SSL/TLS certificates.
What information can be extracted from an SSL certificate?
An SSL certificate contains the subject (domain name), issuer (Certificate Authority), validity period (not before/not after dates), serial number, public key information, signature algorithm, and any Subject Alternative Names (SANs).
Is it safe to paste my SSL certificate into this decoder?
Yes, a certificate is public information that is sent to every client that connects to your server. The decoder also runs locally in your browser, so nothing is transmitted. Never paste your private key, however.
How do I check if my SSL certificate has expired?
Paste the PEM certificate into the decoder and look at the "Not After" date. If that date is in the past, the certificate has expired and browsers will show a security warning to visitors.
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