Local X509 Certificate Reader
Show issuer, names, and validity from a public certificate you open. It does not by itself verify a live trust chain.
Paste the PEM text (-----BEGIN CERTIFICATE-----), or open a .pem, .crt, .cer, or .der file. It stays in this page.
Your result
Paste a certificate to see who it is for, who issued it, and when it ends.
How to use it
- Paste a PEM or base64 certificate.
- Read the issuer, subject, and dates.
- Read that trust was not checked.
Examples
- smart.examplethe PEM certificate for smart.example issuer: smart.example subject: smart.example notBefore: 261113134029Z notAfter: 261115134029Z trust: not checked
- Without the headerthe same certificate as base64 issuer: smart.example subject: smart.example notBefore: 261113134029Z notAfter: 261115134029Z trust: not checked
- Extra blank linesthe same PEM with extra spaces issuer: smart.example subject: smart.example notBefore: 261113134029Z notAfter: 261115134029Z trust: not checked
Tool details and privacy
Paste a certificate. The page walks the DER for common-name values and the first two times. The last line says trust was not checked.
A readable certificate is not a trusted one. The page keeps those facts apart.
Options
- PEM headers are stripped before the DER walk.
- The first common name is shown as the issuer and the second as the subject.
Limits
- Trust is not checked.
- There is no live OCSP request.
- A file that is not a certificate is refused.
Privacy
What you type stays in your browser. Nothing is uploaded or saved on the server.
Questions
Does this prove the certificate is trusted?
No.
Is OCSP contacted?
No.
What does the smart.example sample report?
Issuer and subject smart.example, the two dates in the file, and trust not checked.
Is the certificate uploaded?
No.