Certificate viewer
To open a Certificate file, drop it in the box below. It opens straight away, even with no extension or the wrong one. Your browser opens it on your device: nothing is uploaded.
What you see
| Certificate in the viewer | |
|---|---|
| Read | PEM text and binary DER, one certificate or a whole bundle |
| Validity | Valid, expires in N days, expired N days ago, or not valid yet |
| Chain | Ordered leaf to root; each signature checked with the next certificate’s key |
| Trust | Not checked against any trust store |
| Files with no extension | Opened from their bytes or their BEGIN CERTIFICATE line |
| Extensions | .crt, .cer, .cert, .der, .pem |
| Upload | None: opened on your device |
What is a Certificate file?
A certificate (.crt, .cer, .pem or .der) ties a public key to a name, such as a website’s domain, and is signed by the authority that issued it. It is the file TLS servers, email signing and code signing use.
Who it is for and who issued it, the dates with how many days are left, the alternative names, key usage and extended key usage, whether it is a CA, the key type and size, the signature algorithm, the serial number and the SHA-1 and SHA-256 fingerprints. A file with several certificates is put in chain order, leaf first, with a line saying whether each one is signed by the next.
How to open a Certificate file
- Add your Certificate. Drop the file in the box, choose it or paste it.
- Look at it. Who it is for and who issued it, the dates with how many days are left, the alternative names, key usage and extended key usage, whether it is a CA, the key type and size, the signature algorithm, the serial number and the SHA-1 and SHA-256 fingerprints. A file with several certificates is put in chain order, leaf first, with a line saying whether each one is signed by the next.
- Take it further. Open in hands it, in a new tab, to File converter.
Questions
Drop the .crt or .pem here. The card says how many days are left, or how long ago it expired, with the exact dates in UTC.
Open it here: the SHA-256 and SHA-1 fingerprints are listed in the same form as Windows and OpenSSL print them.
Drop the bundle here. The certificates are shown leaf first, and a line says whether each is signed by the next and whether the root is included.
Only the name. Each can hold the same certificate as PEM text or binary DER; the viewer reads both, and Convert switches between them.
No. The viewer runs in your browser and opens the file on your device. Nothing is sent anywhere.