Can I convert a .cer or .crt file to PEM?

Yes. .cer and .crt files can be either binary DER or text PEM, and both are accepted. The certificate is checked and always returned as a clean PEM file. There are also dedicated CER to PEM and CRT to PEM converters.

What is the OpenSSL equivalent?

openssl x509 -inform der -in certificate.cer -out certificate.pem converts a DER certificate. This converter produces the same PEM: the certificate Base64-encoded in 64-character lines between BEGIN/END CERTIFICATE markers.

How do I convert DER (.der / .crt / .cer) to PEM?

Upload your DER (.der / .crt / .cer) file above, click Convert, and download the PEM result instantly. No account or software needed.

Is converting DER (.der / .crt / .cer) to PEM free?

Yes. It is free and unlimited for files up to 5 MB, with no account required. Larger files get 3 free conversions per day; beyond that, credit packs start at $3 and credits never expire.

Are my files stored or shared?

No. Files are processed in server memory and deleted immediately after conversion. File contents are never written to disk or retained.

Do I need to install anything?

No software installation needed. OmniConvert runs in the browser — just upload, convert, and download.

OmniConvert

Convert DER to PEM

Free

Convert a binary DER certificate to base64-encoded PEM format

Drop a file or click to browse

Accepted: .der,.crt,.cer

Free and unlimited for files up to 5 MB. No account needed.

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About this conversion

Convert a binary DER certificate to base64-encoded PEM format. This converter processes your DER (.der / .crt / .cer) file server-side and returns a PEM file instantly — no account, no software installation, and no file storage. Files are deleted from our servers immediately after conversion.

Learn more: PEM / DER / CER / CRT file format explained

How to convert DER (.der / .crt / .cer) to PEM

1. Upload — drag your DER (.der / .crt / .cer) file onto the converter above, or click to browse.
2. Convert — press Convert. Processing happens on secure servers in seconds.
3. Download — your PEM file downloads automatically. No sign-up required.

Convert DER (.der / .crt / .cer) to PEM from the command line

curl --fail-with-body \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -F "file=@input.der" \
  -F "conversionId=der-to-pem" \
  https://www.omniconvert.cloud/api/convert -o output.pem

The API needs a token from a credit pack, and each API conversion uses one credit. Converting on this page stays free. API documentation

Frequently Asked Questions

Can I convert a .cer or .crt file to PEM?: Yes. .cer and .crt files can be either binary DER or text PEM, and both are accepted. The certificate is checked and always returned as a clean PEM file. There are also dedicated CER to PEM and CRT to PEM converters.
What is the OpenSSL equivalent?: openssl x509 -inform der -in certificate.cer -out certificate.pem converts a DER certificate. This converter produces the same PEM: the certificate Base64-encoded in 64-character lines between BEGIN/END CERTIFICATE markers.
How do I convert DER (.der / .crt / .cer) to PEM?: Upload your DER (.der / .crt / .cer) file above, click Convert, and download the PEM result instantly. No account or software needed.
Is converting DER (.der / .crt / .cer) to PEM free?: Yes. It is free and unlimited for files up to 5 MB, with no account required. Larger files get 3 free conversions per day; beyond that, credit packs start at $3 and credits never expire.
Are my files stored or shared?: No. Files are processed in server memory and deleted immediately after conversion. File contents are never written to disk or retained.
Do I need to install anything?: No software installation needed. OmniConvert runs in the browser — just upload, convert, and download.

No account needed · Credits never expire · Share your token link across devices