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What Is a Wildcard SSL Certificate?
If you manage a website with multiple subdomains, you have likely come across the term wildcard SSL certificate. Understanding what it is, how it works, and whether it is the right choice for your website can save you considerable time and money. In this guide, we will break down everything you need to know about wildcard SSL certificates in plain, straightforward language.
Understanding SSL Certificates
Before diving into wildcard SSL certificates specifically, it helps to understand what an SSL certificate is in the first place. SSL stands for Secure Sockets Layer, though modern implementations actually use its successor, TLS (Transport Layer Security). An SSL certificate is a digital certificate that authenticates a website’s identity and enables an encrypted connection between a web server and a user’s browser.
When a website has a valid SSL certificate installed, visitors will see a padlock icon in their browser’s address bar, and the URL will begin with https:// rather than http://. This encryption protects sensitive data such as login credentials, payment information, and personal details from being intercepted by malicious third parties.
SSL certificates come in several types, each suited to different needs. A standard single-domain SSL certificate covers just one domain. A multi-domain SSL certificate, also known as a Subject Alternative Name (SAN) certificate, covers several specific domains. And then there is the wildcard SSL certificate, which takes a different and often more flexible approach.
What Is a Wildcard SSL Certificate?
A wildcard SSL certificate is a type of SSL/TLS certificate that secures a primary domain and an unlimited number of its first-level subdomains using a single certificate. The term “wildcard” refers to the asterisk (*) used in the certificate’s common name, which acts as a placeholder for any subdomain.
For example, a wildcard SSL certificate issued for *.yourdomain.co.uk would automatically secure all of the following:
- www.yourdomain.co.uk
- mail.yourdomain.co.uk
- shop.yourdomain.co.uk
- blog.yourdomain.co.uk
- support.yourdomain.co.uk
This means that no matter how many subdomains you create, they are all protected under the same certificate, without the need to purchase and manage individual certificates for each one.
How Does a Wildcard SSL Certificate Work?
The wildcard SSL certificate works by using the asterisk (*) as a wildcard character in the domain name. When a browser connects to a subdomain covered by the certificate, the server presents the wildcard certificate, and the browser verifies that the subdomain matches the wildcard pattern. As long as the subdomain is at the same level as the asterisk, the certificate is considered valid.
It is important to note that a wildcard SSL certificate only covers one level of subdomains. This means that while shop.yourdomain.co.uk would be covered, a second-level subdomain such as payments.shop.yourdomain.co.uk would not be. If you need to secure multiple levels of subdomains, you would require additional certificates or a different solution.
Key Benefits of a Wildcard SSL Certificate
Cost-Effective for Multiple Subdomains
One of the most compelling reasons to choose a wildcard SSL certificate is the cost saving it offers. Rather than purchasing a separate SSL certificate for each subdomain — which can quickly become expensive — you pay for a single certificate that covers them all. For businesses that regularly create new subdomains, this can represent a significant reduction in ongoing expenditure.
Simplified Certificate Management
Managing multiple SSL certificates can be a logistical headache. Each certificate has its own expiry date, renewal process, and installation requirements. With a wildcard SSL certificate, you only have one certificate to monitor, renew, and manage. This simplicity reduces the risk of accidentally allowing a certificate to expire, which can cause browser warnings and damage user trust.
Flexibility for Growing Websites
For businesses that are scaling and adding new subdomains regularly, a wildcard SSL certificate offers excellent flexibility. There is no need to go through the process of obtaining a new certificate every time you launch a new subdomain. The wildcard certificate automatically covers any new subdomain you create at the first level, making it ideal for dynamic and growing web environments.
Consistent Security Across Your Domain
A wildcard SSL certificate ensures a consistent level of encryption and security across all your subdomains. This consistency is not only beneficial from a technical standpoint but also helps build trust with your visitors, who will see the same security indicators regardless of which part of your website they are visiting.
Potential Drawbacks to Consider
Security Risk if the Private Key Is Compromised
Because a single wildcard SSL certificate covers multiple subdomains, if the private key associated with the certificate is ever compromised, all subdomains covered by that certificate are potentially at risk. This is in contrast to individual certificates, where a compromise would only affect a single subdomain. Organisations with very high security requirements may prefer separate certificates for this reason.
Limited to First-Level Subdomains
As mentioned earlier, a wildcard SSL certificate does not cover second-level subdomains. If your infrastructure requires multiple levels of subdomains, you will need to plan accordingly and potentially invest in additional certificates.
Not Suitable for Multiple Root Domains
A wildcard SSL certificate is tied to a single root domain. If your organisation operates several entirely separate domains, you would need a wildcard certificate for each one, or consider a multi-domain wildcard certificate instead.
Who Should Use a Wildcard SSL Certificate?
A wildcard SSL certificate is particularly well-suited for:
- E-commerce businesses with separate subdomains for their shop, blog, and customer portal
- SaaS companies that host each client on a unique subdomain
- Media organisations with subdomains for different content sections
- Developers and agencies managing websites with staging and testing environments
- Any business that anticipates creating new subdomains in the future
If you are unsure whether a wildcard SSL certificate is the right solution for your specific situation, it is worth consulting with a digital or domain management specialist. You can find helpful resources and guidance on topics like this at da-manager.com/blog, where a range of articles covering website management and security are available.
How to Obtain a Wildcard SSL Certificate
Wildcard SSL certificates are available from a wide range of Certificate Authorities (CAs), including well-known providers such as DigiCert, Sectigo, and GlobalSign. The process of obtaining one typically involves:
- Generating a Certificate Signing Request (CSR) on your web server, using the wildcard format (e.g., *.yourdomain.co.uk)
- Submitting the CSR to your chosen Certificate Authority
- Completing the domain validation process to prove ownership of the domain
- Receiving the issued certificate and installing it on your server
The level of validation required depends on the type of wildcard certificate you choose. Domain Validated (DV) wildcard certificates are the quickest to obtain, whilst Organisation Validated (OV) certificates require additional verification of your business details.
Final Thoughts
A wildcard SSL certificate is a powerful and practical solution for website owners and businesses that operate multiple subdomains under a single root domain. It offers cost savings, simplified management, and the flexibility to grow without constantly acquiring new certificates. Whilst it does come with a few limitations — particularly around second-level subdomains and the shared risk of a compromised private key — for the vast majority of businesses, the benefits far outweigh the drawbacks.
Whether you are setting up a new website or reviewing your existing security infrastructure, a wildcard SSL certificate is certainly worth considering as a cornerstone of your online security strategy.
This article was originally published in 7 July 2026. It was most recently updated in July 7, 2026 by isaiah
