🔐 Certificate & CSR Tools

Fourteen tools for working with TLS certificates and certificate signing requests — inspect what a live site is serving, generate a CSR, decode one you were sent, build Subject DN/SAN strings, or look up OpenSSL commands, cipher suites and key usage OIDs.

🔒 SSL Checker

Inspect the certificate a live site is serving: issuer, validity dates and chain.

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📝 CSR Generator

Generate a certificate signing request and private key for a new certificate.

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🔍 CSR Decoder

Decode a CSR to check the subject, key size and SANs before you submit it.

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🔑 RSA Generator

Create an RSA key pair and extract the public key from a private key.

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🗝️ EC Key Generator

Generate an elliptic-curve key pair in your browser — the key never leaves your machine.

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⚙️ OpenSSL Helper

Build the right OpenSSL command for common certificate tasks.

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🏷️ Subject DN Builder

Build the Subject DN string for a CSR from CN/O/OU/L/ST/C fields.

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📋 SAN List Builder

Build a Subject Alternative Name list from domains and IPs.

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📅 Certificate Validity Period Calculator

Compute a certificate's expiry date and days remaining.

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🔑 Key Size Security Reference

Compare RSA and EC key sizes to their security strength.

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⚙️ OpenSSL Command Cheat Sheet

Search common OpenSSL commands for certs and keys.

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🔒 TLS Cipher Suite Reference

Look up TLS cipher suites and their current recommendation.

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🗝️ Key Usage & EKU Reference

What each X.509 Key Usage flag and EKU OID means.

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📐 PEM Base64 Line Wrapper

Wrap raw Base64 into valid PEM format with headers.

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