Free SSL Certificate Checker

SSL Certificate Checker

Enter any website URL to check its SSL certificate details

Enter website URL (e.g., google.com, https://example.com)

About SSL Certificate Checker

The SSL Certificate Checker allows you to instantly verify the SSL certificate status of any website. Simply enter a website URL, and the tool will retrieve live certificate information including issuer details, validity period, expiration status, SSL/TLS protocol version, and remaining days before expiry.

This tool connects directly to the website’s server over port 443 and analyzes the active SSL certificate in real time.

What Is an SSL Certificate?

An SSL (Secure Sockets Layer) certificate is a digital certificate that enables encrypted communication between a website and its visitors. When a website uses SSL, its address begins with HTTPS, indicating that the connection is secure.

SSL certificates help:

  • Encrypt data between browser and server

  • Protect sensitive information

  • Verify website identity

  • Prevent unauthorized interception

Every secure website relies on a valid SSL certificate to maintain trust and security.

What Is This SSL Certificate Checker?

This SSL Certificate Checker is a web-based tool that:

  • Accepts a website URL or domain name

  • Establishes a secure connection to the server

  • Retrieves the website’s SSL certificate

  • Extracts important certificate details

  • Determines whether the certificate is valid or expired

The tool processes one domain at a time and provides structured results instantly.

Why Check an SSL Certificate?

Checking an SSL certificate is important for:

  • Verifying that a website's certificate is still valid

  • Monitoring certificate expiration dates

  • Ensuring HTTPS security is active

  • Identifying SSL/TLS protocol versions

  • Confirming the issuing authority

Regular SSL monitoring helps prevent unexpected website downtime due to expired certificates.

Key Features of This SSL Certificate Checker

The following features are directly implemented in the tool:

Live SSL Certificate Retrieval

The tool creates a secure socket connection to the website on port 443 and retrieves the active SSL certificate in real time.

Automatic URL Handling

If a user enters a domain without http:// or https://, the tool automatically adds https:// before processing.

Domain Cleanup

The tool extracts and cleans the domain name:

  • Removes any port numbers

  • Validates the domain format

Validity Period Detection

The tool extracts:

  • Certificate start date (Valid From)

  • Certificate expiration date (Valid Until)

Days Remaining Calculation

It calculates how many days remain before the certificate expires using the current date.

Valid / Expired Status Classification

Based on the remaining days:

  • Displays Valid (X days remaining)

  • Displays Expired (X days ago)

Issuer Identification

Shows the certificate’s issuing organization (Certificate Authority).

Common Name (CN) Display

Extracts and displays the certificate’s Common Name from the subject field.

SSL/TLS Protocol Version

Displays the SSL/TLS protocol version used in the secure connection.

Download Results as CSV

After checking a certificate, users can download a CSV report containing:

  • Domain Name

  • Issuer

  • Valid From

  • Valid Until

  • Days Remaining

  • SSL Version

  • Common Name

  • Status

How This Tool Works

The SSL checking process follows these steps:

Step 1: URL Input

The user enters a website URL or domain name.

Step 2: URL Formatting

If no scheme is provided, https:// is automatically added.

Step 3: Domain Extraction

The tool extracts the domain and removes any port number.

Step 4: Secure Connection

A socket connection is created to the domain on port 443 using a secure SSL context.

Step 5: Certificate Retrieval

The server’s SSL certificate is retrieved using getpeercert().

Step 6: Data Parsing

The tool extracts:

  • Issuer details

  • Subject Common Name

  • Validity dates

Step 7: Expiry Calculation

The tool calculates the difference between the current date and the expiration date.

Step 8: Status Generation

The tool determines whether the certificate is valid or expired.

Step 9: Result Display

All information is displayed in a structured result table.

SSL Certificate Information Explained

➤ Domain Name

The website domain being checked.

➤ Issuer / Authority

The organization that issued the SSL certificate.

➤ Valid From

The date and time when the certificate became active.

➤ Valid Until

The expiration date and time of the certificate.

➤ Days Remaining

The number of days before the certificate expires.
If negative, the certificate is expired.

➤ SSL Version / Protocol

The SSL/TLS protocol version used during the connection.

➤ Common Name (CN)

The primary domain name listed inside the certificate.

➤ Status

Displays either:

  • Valid (with remaining days)

  • Expired (with number of days since expiration)

Download SSL Certificate Report

After successfully checking a certificate, users can download the results in CSV format.

The file name includes:

  • Domain name

  • Timestamp

The CSV contains all certificate details shown in the results table.

User Interface Features

The SSL Certificate Checker includes:

  • Clean URL input field

  • Enter key support

  • Loading spinner during processing

  • Disabled button while checking

  • Smooth scroll to results

  • Clear All button

  • Download CSV button

  • Responsive layout

  • Light theme support

  • Safe HTML escaping for output

Who Should Use This Tool?

This tool is useful for:

  • Website owners monitoring certificate validity

  • Developers verifying HTTPS configuration

  • DevOps engineers checking SSL status

  • IT administrators auditing security

  • Anyone ensuring website encryption is active

The SSL Certificate Checker provides a fast and reliable way to verify SSL certificate details for any website. It retrieves live certificate data, calculates expiration status, identifies issuing authority, detects SSL protocol versions, and allows results to be exported as a CSV report.

By checking SSL certificates regularly, users can prevent unexpected certificate expiration issues and maintain secure website connections.

Frequently Asked Questions

Learn more about SSL certificates, validity checks, and how to keep your website secure and trusted.

If you enter a domain like example.com, the tool automatically adds https:// before processing. This ensures the SSL connection can be established correctly.

Yes. The tool connects to the website using port 443, which is the standard port for HTTPS and SSL/TLS connections.

The tool reads the certificate’s expiration date (notAfter) and compares it with the current system date. The difference in days determines how many days remain before expiration. If the result is negative, the certificate is already expired.

The status is based entirely on the calculated days remaining:

  • If days remaining is greater than 0 → the certificate is marked Valid.

  • If days remaining is less than or equal to 0 → the certificate is marked Expired.

The SSL Version field displays the protocol version used during the secure connection with the server. This is retrieved directly from the SSL socket connection.

The Issuer value is extracted from the certificate’s issuer field. Specifically, the tool retrieves the organizationName from the certificate metadata. If it is not available, it displays “Unknown.

The Common Name is extracted from the certificate’s subject field. It typically represents the primary domain that the certificate was issued for.

Yes, the checker also identifies the TLS/SSL protocol version used by your site to ensure compatibility with modern browsers and security standards.

If the domain cannot be resolved (DNS failure), the tool returns an error message stating that it was unable to resolve the domain name.

Absolutely! The SSL Certificate Checker is perfect for web developers, SEO agencies, and IT professionals managing multiple domains.

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