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Public Key Format Converter
Convert supported public JWK and SPKI key formats with complete file companions.
Conversion, Public key, Optional public source file (takes precedence)
JWK, PEM, DER, JSON
Browser only
Runs locally in your browser. Your files, pasted content and generated output are not uploaded. Reset clears this tool’s working data.
This tool needs JavaScript. If it does not load, refresh the page and try again.
How to use this tool
- Enter the displayed example values,or choose the local input files requested by the controls. Optional source files take precedence where labelled.
- Choose Convert public key and inspect the complete result and any reported limitations.
- Use Download result and each companion download link to save complete outputs. Reset clears output and restores example controls.
Examples
Conversion: jwk-to-spki
Public key: {
"kty": "OKP",
"crv": "Ed25519",
"x": "oReoyKPYiOaV3lPiGqvYuDi_UGvwcHCKoeroLrEZt9Y"
}
Limitations
- Convert public JWK and SPKI PEM/DER key material for RSA2048–8192 bits,P-256/P-384/P-521,Ed25519 or X25519. Download complete JWK,PEM and DER companions. Retain source JWK metadata separately because SPKI cannot carry it. Private/symmetric keys,PKCS1 and constrained RSA-PSS SPKI algorithms refuse. Supported material is imported by WebCrypto;this does not establish ownership or trust. Up to100,000 characters per pasted field,128 KiB per optional file,400,000 combined input bytes and4 MiB output. ASN.1 trees are bounded to20,000 nodes/40 levels. All processing stays in your browser.
- Complete outputs only. Unsupported or oversized input is refused. Follow the displayed job-specific bounds and format policies.
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