CER to CSR Converter - Generate .csr from Existing .cer and Key Online | JavaInUse

Convert CER to CSR - Free Online

Regenerate a Certificate Signing Request (.csr) from an existing certificate (.cer) and its private key. Files are processed securely on the server and deleted immediately.

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About CER to CSR Conversion

A CSR (Certificate Signing Request) carries the subject details and public key that a Certificate Authority signs to issue a certificate. When you need to renew or reissue a certificate but no longer have the original request, this tool recreates a matching .csr from your existing certificate and private key using openssl x509 -x509toreq. The subject fields are copied from the certificate.

Convert and package keys for SSH, TLS, and keystore workflows.

PPK -> PEM Convert PuTTY keys to PEM PEM -> PPK Create PuTTY-ready keys PEM -> OpenSSH Rewrap PEM keys to OpenSSH PEM -> DER Binary DER output from PEM PKCS#1 -> PKCS#8 Modernize RSA private keys PKCS#8 -> PKCS#1 Generate legacy key material JKS -> PEM Export PEM keys and certs from JKS PEM -> JKS Build Java keystores from PEM assets PFX/P12 -> PEM Extract keys and chains from PKCS#12 PEM -> CRT Convert PEM certificates to CRT format CRT -> PEM Convert CRT certificates to PEM format CRT -> DER Convert PEM .crt to binary DER DER -> CRT Convert binary DER to PEM .crt CRT -> CER Convert .crt certificate to .cer CER -> CRT Convert .cer certificate to .crt CRT -> Base64 Encode certificate to Base64 Base64 -> CRT Decode Base64 to .crt certificate CER -> DER Convert PEM .cer to binary DER DER -> CER Convert binary DER to PEM .cer DER -> BASE64 Encode binary DER certificate to Base64 DER -> PFX Bundle DER certificate and key into .pfx DER -> P12 Bundle DER certificate and key into .p12 DER -> CSR Generate CSR from DER certificate and key CER -> PEM Convert .cer certificate to .pem CER -> BASE64 Encode .cer certificate to Base64 CER -> PFX Bundle .cer and key into .pfx CER -> P12 Bundle .cer and key into .p12 CER -> CSR Regenerate signing request from cert PEM -> CER Convert .pem certificate to .cer PEM -> BASE64 Encode .pem certificate to Base64 PEM -> P12 Bundle .pem and key into .p12 PEM -> CSR Regenerate signing request from cert JKS -> PFX Convert Java Keystore to PKCS#12 PFX -> JKS Convert PKCS#12 to Java Keystore PEM -> JWK Convert PEM keys to JSON Web Key JWK -> PEM Convert JSON Web Key to PEM PKCS#8 -> JWK Convert PKCS#8 keys to JWK JWK -> PKCS#8 Convert JSON Web Key to PKCS#8 DER -> PEM Convert binary DER to PEM format OpenSSH -> PEM Convert OpenSSH keys to PEM PEM -> P7B Bundle certificates into PKCS#7 P7B -> PEM Extract certificates from PKCS#7 PEM -> PFX Create PKCS#12 from key and cert CRT -> PFX Bundle .crt and key into .pfx CRT -> P12 Bundle .crt and key into .p12 PFX -> CRT Extract certificate from .pfx PFX -> BASE64 Encode .pfx archive to Base64 PFX -> CER Extract .cer certificate from .pfx PFX -> DER Extract binary DER certificate from .pfx PFX -> P12 Repackage .pfx into .p12 archive PFX -> CSR Generate signing request from .pfx P12 -> CRT Extract certificate from .p12 P12 -> PEM Extract certificate and key as .pem P12 -> Base64 Encode .p12 archive to Base64 P12 -> CER Extract certificate as .cer P12 -> DER Extract certificate as binary .der P12 -> PFX Repackage .p12 into .pfx archive P12 -> CSR Generate signing request from .p12 CRT -> CSR Regenerate signing request from cert CSR -> CRT Sign CSR into self-signed cert CSR -> PEM Re-encode signing request as .pem CSR -> Base64 Encode signing request to Base64 CSR -> CER Self-sign CSR into .cer certificate CSR -> DER Re-encode signing request as binary .der CSR -> P12 Self-sign CSR into .p12 archive CSR -> PFX Self-sign CSR into .pfx archive PEM Passphrase Add or remove key passphrase SSH Fingerprint Generate MD5/SHA256 fingerprints Ed25519 Generator Generate modern Ed25519 SSH keys Certificate Decoder View certificate details and SANs CSR Decoder View CSR details before submission Chain Validator Validate certificate chain order PEM Splitter Split multi-cert PEM bundles SSL Checker Check website SSL certificate SPKI Hash Generate cert pinning hash PEM to K8s Secret Create Kubernetes TLS secrets

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