About Certificate Parser
Certificate Parser reads common X.509 certificate and certificate-chain formats so you can inspect identity, validity, extensions, and fingerprints without installing a desktop utility.
Use it when debugging TLS deployments, checking a certificate renewal, or comparing the certificate served by different environments. The parser shows what is present in the file; it does not prove that a certificate is trusted by every client or that a private key matches it.
How to use this developer tool
- Paste PEM text or upload a PEM, DER, PFX, or PKCS#12 file.
- If the file is password-protected, enter its password only for this local inspection.
- Review the subject, issuer, SANs, validity dates, key details, algorithms, and fingerprints, then check the warnings.
Privacy and data handling
Certificate files and optional PFX passwords are processed locally in the browser. They are not intentionally sent to Dev Tools, but you should still use a non-production copy when possible and never share a private key with a third party.
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Frequently asked questions
Does parsing a certificate verify trust?
No. Parsing displays the certificate contents. Trust also depends on the client trust store, chain construction, hostname, revocation policy, and the server configuration.
Can I upload a private key?
The tool is intended for certificate inspection. Do not upload a private key unless the page explicitly asks for a supported key format and you have accepted the security risk.
What does an expired certificate warning mean?
It means the certificate validity window does not include the current date. Clients may reject it even when the file is otherwise well formed.