Certificate decoder
Paste a PEM certificate to see its subject, alternative names, dates, key size, usages and thumbprints.
Public certificate only. Never paste a private key.
Runs in your browser. Nothing you type is sent to the server.
About this tool
Paste a certificate that starts with BEGIN CERTIFICATE, such as one exported from a domain controller, a web server or a load balancer. The decoder reads it in your browser and shows who it was issued to, the names it covers, how long it is valid, the key type and size, and what it may be used for. For domain controller certificates look for Server Authentication and KDC Authentication under enhanced key usage, and the controller's full name in the alternative names. Only the public certificate is read; never paste a private key. Nothing leaves this page.