SSL Certificate Decoder & Inspector
Decode PEM certificates and inspect issuer, subject, SANs, validity windows, algorithms, and fingerprints locally in your browser with no server upload.
Decode PEM certificates locally to inspect issuer, subject, validity, SAN entries, algorithms, and SHA-256 fingerprint without uploading certificate material.
ASN.1 Certificate Decoding
Parses PEM certificates into structured fields including serial number, issuer, subject, validity windows, and algorithm identifiers.
SAN and Fingerprint Inspection
Extracts Subject Alternative Name entries (DNS, IP, URI, email) and computes SHA-256 fingerprint for trust-chain diagnostics.
Local-Only Analysis
Certificate data is decoded directly in your browser without server upload, supporting private security reviews and incident response workflows.
Free and Unlimited
Inspect as many certificates as needed with no signup, making it suitable for engineering, DevOps, and security teams.
TLS Deployment Verification
Inspect certificates before deployment to verify issuer, subject, SAN hostnames, and validity dates.
Incident Response
Analyze suspicious certificates from logs to identify mismatched SANs, expired certs, or weak algorithm assumptions.
Domain Migration Audits
Confirm multi-domain SAN coverage during infrastructure migrations and load balancer updates.
Certificate Inventory Normalization
Convert PEM input into readable reports and JSON records for internal certificate inventory systems.
Compliance Reviews
Review cryptographic metadata and expiration timelines during internal security and compliance audits.
DevOps Automation Testing
Validate output from certificate issuance pipelines and ensure generated cert fields match expected policy.
SSL Certificate Decoder & Inspector parses X.509 PEM certificates locally in the browser and extracts key trust and identity fields. It is built for practical TLS diagnostics where engineers need readable metadata without sending certificates to external services.
Decoded Certificate Fields
The inspector extracts subject and issuer distinguished names, serial number, validity period, signature algorithm, public key algorithm, SAN extension values, and SHA-256 fingerprint.
Browser-Side Parsing
Parsing is done with a lightweight ASN.1 decoder implemented client-side, allowing direct PEM inspection in restricted environments where uploading certificate material is not acceptable.
Operational Value
Certificate expiration and SAN mismatches are common outage causes. This tool helps teams quickly inspect cert contents during deployments, incident triage, and compliance checks.
Related Tools
RSA/ECDSA Key Generator
Generate cryptographically secure RSA and ECDSA public/private key pairs using the Web Crypto API - Free online key generator
Cryptographically Secure Password Generator
Generate high-entropy passwords with browser cryptographic randomness and policy controls - Free secure password generator
UUID / GUID Batch Generator
Generate batches of up to 10,000 cryptographically secure UUID v4 (random) or UUID v7 (time-ordered) identifiers in your browser - Free online UUID generator
AES File Encryptor/Decryptor
Encrypt and decrypt files locally using AES-256-GCM with PBKDF2 passphrase-based key derivation - Free online AES file encryptor
Frequently Asked Questions About SSL Certificate Decoder & Inspector
This tool accepts PEM-encoded X.509 certificate blocks, typically .pem, .crt, or .cer files containing BEGIN CERTIFICATE and END CERTIFICATE markers.
Yes. The inspector extracts SAN extension entries including DNS names, IP addresses, email values, and URI entries when present in the certificate.
No. This tool decodes and inspects an individual certificate. Full trust-chain validation, revocation checks, and OCSP logic should still be handled by TLS clients and backend validators.
The tool computes SHA-256 fingerprint directly from the DER certificate bytes using browser Web Crypto APIs, giving a deterministic identifier for comparison and pinning workflows.
No. Certificate decoding runs entirely in your browser and does not upload PEM contents to remote servers, helping preserve confidentiality during security diagnostics.
Yes. The decoder surfaces notBefore and notAfter fields clearly so you can confirm whether a certificate is expired or not yet valid.
Yes. It is free to use without signup and can be used repeatedly across development, staging, and production troubleshooting workflows.