SSL Certificate Decoder
Decode a PEM certificate into subject, issuer, validity and serial — locally.
See how it works
Watch a quick simulation of this tool in action — no file needed.
How to use SSL Certificate Decoder
Follow these steps — everything happens instantly in your browser.
- 1
Step 1. Paste your PEM certificate (including the BEGIN/END CERTIFICATE lines).
- 2
Step 2. Click “Decode certificate” — we base64-decode it to DER.
- 3
Step 3. Review subject, issuer, validity window, serial, signature algorithm and key algorithm.
- 4
Step 4. Check the validity badge (valid / expiring soon / expired) and copy the raw DER hex if needed.
Why use this tool
Private by design
All processing happens locally in your browser. Open DevTools → Network and you'll see zero file uploads. Ever.
Instant
No upload wait, no queue, no server round-trip. Results appear the moment you drop a file.
Free & unlimited
No accounts, no watermarks, no daily caps. Use it as many times as you like, forever.
Works everywhere
Desktop, tablet or phone — every tool is responsive and installable as a PWA for offline use.
Frequently asked questions
Everything you might want to know about ssl certificate decoder.
File Checksum
Compute SHA-1, SHA-256 and SHA-512 for any file — locally, never uploaded.
Encrypt & Decrypt Text
AES-GCM 256 encryption with a passphrase — round-trip in your browser.
Secure Notes
A local-only encrypted notepad — passphrase-locked with AES-GCM 256.
Password Strength Checker
Estimate entropy and crack time for any password — fully offline.