About PEM/DER Converter
Convert certificates, private keys, and CSRs between PEM and DER formats. PEM is a Base64-encoded format with readable headers, while DER is binary. Drag and drop files or paste content directly. Auto-detects input format and content type.
How to Use
- 1Drag & drop a certificate/key file or paste content
- 2For DER input, select the content type (certificate, key, CSR)
- 3Click Convert to transform between formats
- 4Copy the output or download the converted file
Key Features
- Bidirectional PEM ↔ DER conversion
- Auto-detect input format
- Support for certificates, private keys, public keys, and CSRs
- Drag and drop file upload
- Copy or download converted output
- Proper PEM headers for each content type
- Client-side conversion - files never uploaded
Common Use Cases
Frequently Asked Questions
What is the difference between PEM and DER?
PEM is Base64-encoded with headers/footers (-----BEGIN CERTIFICATE-----), making it human-readable. DER is binary, smaller, and commonly used by Java applications.
How do I know which format I have?
PEM files are text with BEGIN/END headers. DER files are binary and cannot be read in a text editor. File extensions are not always reliable.
Why do I need to select content type for DER?
DER format has no headers to indicate content type. For PEM output, we need to know whether it's a certificate, key, or CSR to add correct headers.
Privacy First
All processing happens directly in your browser. Your files never leave your device and are never uploaded to any server.
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