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Crypto & Hash

Certificate Format Converter — PEM, DER, P7B, and PFX Inspector

Convert X.509 certificates between PEM and DER, inspect bundles, extract PKCS#7 certificates, and locally inspect password-protected PKCS#12/PFX files.

Free to use No sign-up Runs in your browser

Tool workspace

All parsing and conversion runs locally in this browser tab. Files, passwords, certificates, and private keys are never uploaded or persisted by this tool.

What is a certificate format converter?

X.509 certificates appear as readable PEM blocks or binary DER files. Certificate bundles may use PKCS#7/P7B, while PKCS#12/PFX stores can combine certificate chains and password-protected private keys. This browser-only tool detects those formats, converts single certificates between PEM and DER, lists bundle contents, and extracts certificate PEM blocks without sending security material to a server.

How to convert or inspect certificate files

  1. 1Paste PEM certificate text, or select a DER, P7B, P7C, PFX, or P12 file.
  2. 2For a password-protected PKCS#12 file, enter its password and run local inspection.
  3. 3Review the detected format and each certificate's subject, issuer, serial number, validity, and signature algorithm.
  4. 4Download extracted certificates as PEM, or convert exactly one pasted PEM certificate to a DER file.
  5. 5If a private key is exposed from PFX, move it only to a trusted destination and immediately clear the page.

Common certificate conversion use cases

Preparing a certificate for a server or appliance

Convert one PEM certificate to binary DER or turn a DER certificate into portable PEM text for configuration and deployment.

Inspecting a certificate chain

Open pasted PEM chains and PKCS#7/P7B bundles to identify the leaf and issuing certificates before installation.

Recovering material from a PFX backup

Locally inspect a password-protected PKCS#12/PFX store and export its certificates and private key as PEM with explicit handling warnings.

Frequently asked questions

Are my PFX password and private key uploaded?

No. Processing happens in the current browser tab. This tool does not upload or intentionally persist inputs or outputs, but you should still use a trusted device and clear sensitive output when finished.

Can a PEM certificate bundle be converted into one DER file?

No. A plain DER X.509 file represents one certificate. The tool rejects multi-certificate PEM-to-DER requests instead of producing a misleading file. Use PKCS#7 or separate DER files when a workflow needs a chain.

Does every PKCS#12 or PKCS#7 variant work in a browser?

No. Browser-compatible libraries may not support every legacy cipher, hardware-backed key, unusual bag type, or PKCS#7 content type. Unsupported inputs produce a clear error rather than fabricated output.