Microdeck.tools 100% In-Browser

SSL Certificate & CSR Decoder (PEM / DER)

100% Offline

Decode SSL/TLS certificates, multi-cert chains, and CSR (PKCS#10) requests offline to inspect Subject/Issuer DNs, SAN domains, expiration dates, key strength, SHA-256/SHA-1 fingerprints, and export PEM or binary DER.

100% In-Browser No Server Storage Instant Results
100% Local X.509 ASN.1 Parsing — Zero Server Transmission

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How It Works Under the Hood

node-forge ASN.1 X.509 parsers decode PEM blocks or binary DER buffers locally in browser RAM, extracting Subject/Issuer attributes, Subject Alternative Names, validity windows, public key bit-lengths, and SHA-1/SHA-256 fingerprints.

Step-by-Step Instructions

1

Paste one or more -----BEGIN CERTIFICATE----- / CSR PEM blocks or upload a .pem/.crt/.der file.

2

Inspect expiration countdown badges, SAN domains, Issuer chain, and SHA-256 fingerprint.

3

Export individual certificates as standardized PEM or binary DER.

Key Features & Performance

  • Multi-Certificate Chain Parsing: Inspects leaf, intermediate, and root certificates in one paste
  • CSR (PKCS#10) Support: Verify SANs and Subject fields before submitting to a CA
  • Expiry & Health Badges: Highlights Valid, Expiring Soon (≤30 days), and Expired certificates
  • Local PEM ↔ DER Conversion: Convert certificate encodings without OpenSSL CLI

Local Browser Processing & Privacy

Traditional web converters upload your documents, snippets, or media files to remote servers. SSL Certificate & CSR Decoder (PEM / DER) runs inside your browser tab:

Processed in This Tab

Your input text and files are processed locally without uploading payloads to a processing server.

No Tool Payload Logging

Microdeck does not log or store the files or inputs you paste into tool workspaces (normal static hosting/CDN requests still load page assets).

Tab Memory Lifecycle

Working outputs stay in your browser tab and are released when you reset the tool or close the tab.

Frequently Asked Questions

Is it safe to decode internal Kubernetes or corporate certificates here?

Yes. All ASN.1 decoding runs 100% inside browser memory — internal SANs and organizational metadata never touch any server.

Should I ever paste a Private Key into a decoder?

No tool needs your private key to inspect a public SSL certificate or CSR — stick strictly to public .crt/.pem/CSR blocks.

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