English

Decode and parse SSL/TLS certificates to view detailed information including issuer, subject, validity dates, and encryption details.

Request Feature / Support

6,332+

Total Calculations Run

< 15ms

Browser Execution Speed

100%

Client-Side Privacy

4.9 / 5.0

User Satisfaction

Worked Example & Common Values

Below is a sample worked calculation demonstrating how English processes input data instantly inside your browser.

Sample Input Minified string: {"id":1,"status":"active","roles":["admin"]}

Computed Result

{
  "id": 1,
  "status": "active",
  "roles": [
    "admin"
  ]
}

Execution Mode Client-Side In-Browser JS

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About This Tool

This SSL Certificate Decoder tool allows you to parse and decode SSL/TLS certificates in various formats including PEM, DER, and CRT. Simply paste your certificate text or upload a certificate file, and the tool will extract and display all important certificate details such as issuer information, subject details, validity period (not before/after dates), public key information, signature algorithm, extensions, and more. The tool works entirely client-side for privacy and speed, with no data sent to servers.

Save your calculation history with a free account

How to Use

Paste your SSL/TLS certificate text (in PEM format) into the text area OR click the upload area to select a certificate file (.pem, .crt, .der)
Click the 'Decode Certificate' button
View the decoded certificate information including issuer, subject, validity dates, and technical details
Use the 'Clear' button to reset the form and decode another certificate

Frequently Asked Questions

Find Quick Answers

What certificate formats does this tool support?

The tool supports PEM format (text-based with BEGIN/END CERTIFICATE headers), CRT files, and DER binary format. For PEM format, simply paste the text. For files, upload .pem, .crt, or .der files.

Is my certificate data secure?

Yes, all processing happens entirely in your browser (client-side). No certificate data is sent to any server, ensuring complete privacy and security.

What information can I see from a decoded certificate?

You can view issuer details, subject information, validity dates (not before/not after), public key algorithm and size, signature algorithm, serial number, version, extensions (SAN, key usage, etc.), and fingerprint.

Can I decode expired certificates?

Yes, the tool can decode both valid and expired certificates. The validity dates will be displayed, and you can see if the certificate is currently valid based on current date.

Need to run multiple calculations?

Create a free account today to unlock unlimited daily runs, access advanced parameters, save your history, and request custom features.

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