OmniConvert

Convert X.509 certificate to JSON

Decode an X.509 certificate (PEM or DER) and extract fields as JSON

Drop a file or click to browse

Accepted: .pem,.crt,.cer,.der

or paste below

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

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About this conversion

Decode an X.509 certificate (PEM or DER) and extract fields as JSON. This converter processes your PEM / DER certificate file server-side and returns a JSON 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 PEM / DER certificate to JSON

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

Convert PEM / DER certificate to JSON from the command line

curl --fail-with-body \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -F "file=@input.pem" \
  -F "conversionId=x509-to-json" \
  https://www.omniconvert.cloud/api/convert -o output.json

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

Which certificate formats can I upload?
PEM files (text starting with -----BEGIN CERTIFICATE-----, often named .pem, .crt or .cer) and binary DER files (.der, .cer). You can also paste the PEM text directly.
Which fields are extracted?
Subject, issuer, validFrom, validTo, serial number, SHA-1 and SHA-256 fingerprints, key usage, subject alternative names (SANs), authority information access and whether the certificate is a CA.
Is it safe to upload a certificate?
Certificates are public by design: browsers receive them from every HTTPS server. Never upload a private key (-----BEGIN PRIVATE KEY-----); it is not needed to decode a certificate.
How do I convert PEM / DER certificate to JSON?
Upload your PEM / DER certificate file above, click Convert, and download the JSON result instantly. No account or software needed.
Is converting PEM / DER certificate to JSON 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