Certificate Converter
Upload a certificate in PEM, DER, PKCS#7 or PKCS#12 format and convert it to the format your server or device needs. Conversion happens in your browser.
- Runs in your browser
- Free to use
About this tool
Certificates come as PEM from Let's Encrypt, DER from a corporate CA, P7B from a Windows export and PFX from IIS, and every server wants a different one. The Certificate Converter reads PEM, DER, PKCS#7 and PKCS#12 (with password), lists the certificates it found with subject, issuer, expiry and fingerprint, and writes the format you choose, including a new password-protected PFX when you supply the private key. The whole conversion runs in your browser.
Inspect the result with the PEM Decoder, or create a new self-signed certificate with the SSL Certificate Generator.
How to use it — quick steps
- 01
Add the certificate
Drop or choose the file; the format is detected automatically, or pick it yourself from the list.
- 02
Choose the target format
PEM, DER, PKCS#7 bundle or PKCS#12; for a PFX also set a password and paste the private key if needed.
- 03
Press "Convert certificate"
The converted file appears with a download link, the certificates it holds and the PEM text to copy.
Key features of this tool
All four formats
PEM (Base64 with headers), DER (binary), PKCS#7/P7B chain bundles and PKCS#12/PFX bundles with the private key, in any direction.
PFX in and out
Open password-protected PFX files and build new ones with a password of your choice; the private key is required only for PFX output.
Converted on your device
Parsing and encoding run in your browser with the node-forge library; certificates and keys are never uploaded.
Frequently asked questions
Which format do I need?
PEM for Nginx, Apache, HAProxy and most Linux software; DER (.cer) for Java keystores and some Windows tools; P7B for IIS and Java chain imports; PFX/P12 for IIS, Exchange, Azure and anything that needs the certificate and key in one file.
My PFX conversion asks for a private key
A PKCS#12 bundle must contain the private key. If your source file is a certificate only (PEM, DER, P7B), paste the matching key in PEM format in the field provided.
Are EC keys supported?
EC certificates convert fine in every direction; building a PFX from a separate EC private key is not supported by the library yet, only RSA keys.
Is the password stored?
No, it is used in your browser to decrypt or encrypt the bundle and discarded.
Are my files or data uploaded?
No. The tool is plain JavaScript that runs in your browser; the files or data you provide here are never uploaded to our servers.