How do I check if a website SSL certificate is valid for free?

Enter the domain name in the input field and click Check SSL. The tool instantly fetches the SSL certificate from the server and shows whether it is valid, expired, or expiring soon — along with the exact expiry date and days remaining.

How do I check when my SSL certificate expires online?

Run an SSL check for your domain. The Certificate Overview section shows the exact Valid To date and the number of days remaining before expiry. If the certificate expires within 30 days, an Expiring Soon warning badge is displayed automatically.

What is a Subject Alternative Name in an SSL certificate?

Subject Alternative Names (SANs) are additional domain names or subdomains that a single SSL certificate is authorized to secure. For example, a certificate for example.com may also cover www.example.com, mail.example.com, and *.example.com via SANs.

What is the difference between a wildcard SSL certificate and a regular SSL certificate?

A wildcard SSL certificate (identified by *.domain.com in the SANs) secures a domain and all its direct subdomains with a single certificate. A regular SSL certificate only secures the specific domain names listed in its SANs.

How do I check the SSL certificate issuer of a website?

Run an SSL check for the domain. The Issuer Information card shows the Certificate Authority (CA) common name, organization, and country — for example Let's Encrypt, DigiCert, or Sectigo.

What does SSL certificate fingerprint mean?

An SSL certificate fingerprint is a unique hash of the certificate's contents — either SHA-1 or SHA-256. Fingerprints are used to verify that a certificate has not been tampered with and to uniquely identify a specific certificate across different systems.

Why does my website show an SSL error even though I have a certificate installed?

Common causes include an expired certificate, a certificate issued for a different domain name (CN or SAN mismatch), a self-signed certificate not trusted by browsers, or an incomplete certificate chain missing intermediate CA certificates.

SSL Certificate Checker

Verify SSL validity, expiry date, issuer, fingerprint, and certificate details — free, instant, no signup.

Enter Domain Name

example.com

Valid 📅 Expires: —

Certificate Overview

Issuer Information

Subject Information

Key & Algorithm Details

Fingerprints & Serial

Subject Alternative Names (SANs)

Export or copy your SSL results

About SSL Certificate Checker

An SSL (Secure Sockets Layer) certificate encrypts data between a user's browser and a web server. This tool checks the certificate installed on any domain and shows its validity period, issuer, subject, fingerprints, and Subject Alternative Names (SANs).

Expired or invalid SSL certificates cause browser warnings and can harm SEO rankings. Use this tool to monitor expiry dates and keep your certificates up to date.

Recent Queries

Free SSL Certificate Checker — Verify Any Domain SSL Without Installing Software

If you have ever asked "how do I check if a website has a valid SSL certificate for free" — this tool gives you the answer instantly. The HB Tools SSL Certificate Checker by Haridash fetches the live SSL certificate from any domain and shows you everything — validity status, expiry date, issuer details, fingerprints, and Subject Alternative Names — directly in your browser. No software. No account. Completely free.

Whether you are a developer verifying a newly installed certificate, a site owner checking when your SSL expires, or a security researcher auditing a domain — this tool gives you accurate, real-time certificate data in seconds.

How to Check SSL Certificate Details of Any Website — Step by Step

Type a domain name such as yoursite.com into the input box and click Check SSL. The tool connects to the domain's server, retrieves the live SSL certificate, and displays all details organized into clear sections. You can paste a full URL — the tool automatically strips the https:// prefix.

Results are grouped into Certificate Overview, Issuer Information, Subject Information, Key and Algorithm Details, Fingerprints, and Subject Alternative Names. You can export everything as JSON or CSV, or copy it to your clipboard with one click.

SSL Certificate Fields Explained — What Each Section Means

SSL certificates contain several layers of information. Here is what each part tells you in plain language:

Valid From / Valid To — The start and end dates of the certificate's validity period. Most modern certificates issued by public CAs are valid for 90 days (Let's Encrypt) or up to 1 year (commercial CAs). This tool shows the exact expiry date and the number of days remaining so you can plan renewals in advance.
Issuer (Certificate Authority) — The organization that signed and issued the certificate. Common issuers include Let's Encrypt (free, widely used), DigiCert, Sectigo, and GlobalSign. The issuer's common name (CN), organization (O), and country (C) are all shown.
Subject — The entity the certificate was issued to — typically the domain owner. The Subject Common Name (CN) should match the domain you entered. A mismatch causes browser SSL errors.
Subject Alternative Names (SANs) — The full list of domain names and subdomains this certificate is authorized to secure. Wildcard entries like *.example.com cover all direct subdomains. This is the field browsers actually check to validate a certificate against a domain.
Key Algorithm and Key Bits — Describes the cryptographic key used — most commonly RSA 2048-bit or RSA 4096-bit for strong encryption, or EC (Elliptic Curve) with P-256 or P-384 for faster, equally secure connections.
Signature Algorithm — The algorithm used to sign the certificate, such as SHA256withRSA. Older SHA-1 signatures are now considered insecure and rejected by modern browsers.
Fingerprints (SHA-1 and SHA-256) — Unique hashes of the certificate contents used to verify authenticity. SHA-256 fingerprints are the current security standard; SHA-1 is shown for legacy compatibility only.
Serial Number — A unique identifier assigned by the Certificate Authority to this specific certificate, used for tracking and revocation purposes.

Common SSL Problems This Tool Helps You Diagnose

Here are the most common real-world situations where a free SSL certificate checker saves significant troubleshooting time:

Browser showing "Your connection is not private" warning: Run an SSL check to see if the certificate is expired, self-signed, or issued for a different domain name.
SSL certificate expired without notice: Check the expiry date and days remaining. If the certificate expires within 30 days, this tool shows an Expiring Soon warning badge so you can renew before visitors are affected.
Certificate issued for wrong domain: Compare the Subject CN and SANs against the domain you are checking. If your domain is not listed in the SANs, the certificate will not validate for it.
Wildcard certificate not covering a subdomain: Check the SANs list. A wildcard *.example.com covers sub.example.com but not sub.sub.example.com — second-level subdomains require separate coverage.
Verifying SSL after migration to a new host: Confirm the certificate's issuer and validity dates match what you expect after moving to a new server or CDN provider.
Checking if a newly installed Let's Encrypt certificate is live: Run a check immediately after installation to confirm the certificate is being served correctly and the expiry date is 90 days out.

What Is the Difference Between a Wildcard and a Regular SSL Certificate?

A regular SSL certificate secures only the specific domain names listed in its Subject Alternative Names — for example, example.com and www.example.com. If you need to secure additional subdomains, you need a new certificate or a multi-domain (SAN) certificate.

A wildcard SSL certificate (identified by *.example.com in the SANs) secures the root domain and all direct subdomains with a single certificate — covering blog.example.com, shop.example.com, mail.example.com, and so on. Wildcards do not cover second-level subdomains like api.v2.example.com. This tool clearly labels wildcard certificates with a badge in the summary bar.

What Is a Self-Signed SSL Certificate and Why Do Browsers Reject It?

A self-signed certificate is one where the issuer and the subject are the same entity — the certificate was not signed by a trusted Certificate Authority. While technically it encrypts traffic, browsers display a security warning because there is no independent third party vouching for the certificate's authenticity.

Self-signed certificates are common on internal development servers and network appliances but should never be used on public-facing websites. This tool detects and flags self-signed certificates with a badge so you can identify them immediately.

How Often Should You Check Your SSL Certificate Expiry?

As a best practice, check your SSL certificate expiry at least once a month. If you use auto-renewal (such as Certbot with Let's Encrypt), verify that renewal is working correctly — a failed renewal job is a common cause of unexpected certificate expiry. Commercial certificates issued for one year should be renewed at least 30 days before expiry to allow time for processing and propagation.

This tool shows the exact days remaining alongside a colour-coded warning badge — green for valid, amber for expiring soon, and red for expired — so you can assess the situation at a glance.

Other Free Network & Domain Tools by HB Tools

🔍 WHOIS Lookup 🌐 DNS Lookup 🌍 What's My IP? 🏷️ Meta Tag Generator

Frequently Asked Questions

Enter the domain name and click Check SSL. The tool connects to the domain's server, fetches the live certificate, and instantly shows whether it is valid, expired, or expiring soon — along with the exact expiry date and days remaining. No signup required.

Run an SSL check for your domain. The Certificate Overview section shows the exact Valid To date and the number of days remaining. If the certificate expires within 30 days, an Expiring Soon warning badge appears automatically in the summary bar.

Subject Alternative Names (SANs) are the domain names and subdomains a single SSL certificate is authorized to secure. Browsers check SANs — not the older Common Name field — to validate a certificate. A wildcard entry like *.example.com in the SANs covers all direct subdomains.

A wildcard SSL certificate (shown as *.domain.com in SANs) secures a domain and all its direct subdomains with one certificate. A regular certificate only secures the specific domains listed. Wildcards do not cover second-level subdomains like api.v2.example.com.

Run an SSL check for the domain. The Issuer Information card shows the Certificate Authority common name (CN), organization (O), and country (C) — for example Let's Encrypt, DigiCert, or Sectigo. This tells you which CA issued and is responsible for the certificate.

An SSL fingerprint is a unique hash of the certificate's full contents — either SHA-1 or SHA-256. It uniquely identifies a specific certificate and is used to verify the certificate has not been tampered with. SHA-256 is the current standard; SHA-1 is considered legacy.

Common causes include: the certificate has expired, the domain is not listed in the certificate's SANs, the certificate is self-signed and not trusted by browsers, or the intermediate CA certificate chain is incomplete. Run an SSL check on this tool to identify which issue applies.

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