X.509 Certificate (PEM/CRT) Decoder
Decode and inspect X.509 SSL/TLS certificates (PEM/CRT format) client-side. View Subject, Issuer, Validity Period, SANs, and Serial Number with zero data leaks.
1 How to Use X.509 Certificate (PEM/CRT) Decoder
- 1. Paste PEM certificate.
- 2. View detailed issuer, subject, expiration, and SAN domains.
- 3. Copy parsed JSON.
⚙️ Cryptographic Specifications
- Algorithm
- X.509 ASN.1
- Execution Engine
- Web Cryptography API (SubtleCrypto)
- Environment
- Client Browser Sandbox
- Network Telemetry
- 0 Bytes (Zero Server Transmission)
🛡️ Security & Compliance
Enterprise developers can safely execute this tool with production secrets. Because execution takes place entirely within your browser's local V8 JavaScript runtime, no payloads are transmitted over HTTP, cached on third-party proxies, or stored in server logs.
Verified Safe for SOC2, HIPAA, and GDPR developer compliance audits.
Frequently Asked Questions
What is an X.509 certificate?
A digital certificate format governed by ITU-T standards that binds a public key to an identity using a digital signature.
Is my private key needed?
No, this tool inspects public certificates (CRT/PEM) only.
Related Cryptographic Tools
SSL Certificate Expiry & Validity Checker
Check the exact validity period, notBefore, notAfter, and countdown days remaining before your SSL/TLS certificate expires.
CSR (Certificate Signing Request) Decoder
Decode Certificate Signing Requests (CSR) in PEM format (-----BEGIN CERTIFICATE REQUEST-----). Verify Common Name (CN), Organization, and SANs before submitting to a CA.
SAN (Subject Alternative Name) SSL Inspector
Extract and inspect Subject Alternative Names (SAN) from SSL/TLS certificates. View all authorized domains, subdomains, and wildcard entries.