SSL Certificate Viewer

View and analyze SSL/TLS certificates to check validity, expiration dates, and certificate chain information.

Overview

SSL Certificate Viewer parses PEM-format X.509 certificates directly in your browser, exposing every field that matters: subject and issuer distinguished names, validity window, serial number, signature algorithm, Subject Alternative Names, and the full certificate chain up to the root CA. Because all decoding runs client-side in JavaScript, your certificate data never leaves your machine — a meaningful guarantee when you are inspecting credentials for production servers or internal PKI infrastructure. Paste a PEM block or drop a .crt, .cer, or .pem file and get a structured, human-readable breakdown in seconds.

Common Use Cases

  • Expiry Auditing — Quickly check the Not Before / Not After dates on a certificate to confirm it is still valid before a deployment or audit.
  • Certificate Chain Inspection — DevOps engineers verify that intermediate and root CA certificates are correctly chained so browsers will trust the endpoint without errors.
  • Issuer and Subject Verification — Confirm that a certificate was issued by the expected CA and that the Common Name or SANs match the domain before installing it on a server.
  • Onboarding and Handoff — Developers receiving a certificate from a security team paste it here to understand its scope and expiry without needing OpenSSL installed locally.
  • Debugging TLS Errors — Security engineers inspect a certificate's extension fields and chain to diagnose trust failures or misconfiguration without sending the file to an external service.

How It Works
1

Input Certificate Data

Paste your SSL certificate in PEM format or upload a certificate file (.crt, .cer, .pem).

2

Parse Certificate Information

The tool decodes and displays certificate details including validity dates, subject, issuer, and extensions.

3

Analyze Certificate Chain

View the complete certificate chain, trust path, and identify any issues with certificate validation.

Frequently Asked Questions

What certificate formats are supported?
The tool supports PEM format certificates (Base64 encoded with BEGIN/END headers). You can also view DER certificates by first converting them to PEM format.

Can I check if a certificate is valid?
Yes, the tool shows expiration dates, validity periods, and certificate chain information. However, it doesn't perform live revocation checking or domain validation.

Is it safe to upload certificates here?
Yes, all certificate parsing happens locally in your browser. Certificate data is never transmitted to servers or stored anywhere.

What is a certificate chain?
A certificate chain shows the trust path from your certificate up to a trusted root certificate authority (CA). Each certificate in the chain validates the one below it.

Why is my certificate showing as expired?
Certificates have validity periods with start and end dates. If the current date is outside this range, the certificate is considered expired and browsers will show security warnings.

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