SAN Extractor

Extract all Subject Alternative Names from an SSL certificate

About SAN Extractor

The Subject Alternative Name (SAN) field in an SSL certificate lists all domains and subdomains that the certificate secures. Our SAN Extractor connects to any HTTPS server, retrieves the certificate, and parses the SAN extension to display every DNS name, wildcard entry, and unique apex domain. This is essential for understanding certificate coverage, auditing multi-domain certificates, and verifying that all your domains are properly protected.

How to Use

Enter the domain name (e.g., example.com) of the server whose certificate you want to inspect.
Click "Extract SANs" to fetch and parse the certificate from the server.
Review the extracted SANs — the tool shows total count, DNS names, wildcard entries, and unique apex domains.
Use the certificate info section to verify the issuer, validity period, and serial number.

Use Cases

•Audit multi-domain and wildcard certificates before renewal
•Verify that all required subdomains are covered by a certificate
•Compare SAN lists across different environments (staging vs production)
•Identify unused or unexpected domains in certificate SAN entries

Frequently Asked Questions

A Subject Alternative Name (SAN) is an extension to an SSL certificate that allows it to secure multiple domains and subdomains under a single certificate. SANs replaced the older Common Name (CN) field as the primary way to specify certificate domains.

There is no hard limit, but most Certificate Authorities (CAs) impose practical limits. Standard single-domain certificates include 1 SAN, multi-domain certificates can include 3 to 100+ SANs, and wildcard certificates cover unlimited subdomains under one apex domain.

A regular SAN (e.g., www.example.com) secures only that exact domain. A wildcard SAN (e.g., *.example.com) secures all subdomains at one level, like mail.example.com, blog.example.com, and api.example.com, but not example.com itself.

Tips & Best Practices

•Extract SANs to understand certificate domain coverage
•Use SAN extraction for certificate inventory and documentation
•Verify SANs match your intended domain coverage
•Monitor SAN changes during certificate renewals

Technical Details

Extraction: Subject Alternative Name (SAN) extraction and analysis
Types: DNS names, IP addresses, email addresses, URIs
Validation: SAN format and content validation
Output: Extracted SAN list with type and validation status