How to check a website for an SSL certificate: step-by-step guide

How to check a website for an SSL certificate: step-by-step guide

An SSL certificate is not just a technical detail hidden behind the padlock icon in the address bar. For the average user, it means that the connection to the website is secure, data is transmitted in an encrypted form, and the browser sees no obvious reasons to doubt the authenticity of the resource. For the website owner, it is also a matter of trust: without a valid certificate, it is difficult to appear credible today, even with good design and useful content.

You should check a website for an SSL certificate not only when the browser issues a warning. Sometimes it's better to be sure in advance—especially if you are entering a password, making a payment, sending documents, or just want to understand if you can trust the page. Below is a clear step-by-step guide without unnecessary theory, but with the details that really matter.

1. What is a website's SSL certificate and why should it be checked

A website's SSL certificate confirms that a secure connection has been established between the browser and the server. In practice, this means that data is encrypted, and a person in the middle cannot easily intercept login information, passwords, card numbers, or other sensitive information. Nowadays, people often talk not only about SSL but also about TLS; however, the old name is still commonly used in everyday language and search queries.

Why check the certificate? There are several reasons. First, to ensure that you are indeed opening the correct website and not a counterfeit with a similar address. Second, to determine whether the certificate has expired. Third, to check if it is installed correctly: sometimes the lock is present, but the browser still shows a warning due to errors in the trust chain or due to mixed content. By the way, if it is important for you to assess the reliability of a website as a whole, it is useful to look not only at HTTPS but also at reputational signs — contacts, reviews, company transparency. We have a separate material on this topic: how to check a website for reviews and contacts.

Checking SSL is especially useful in the following cases:

• you are about to enter personal data or a password;
• the site is asking for payment or card linking;
• the browser shows a warning about an insecure connection;
• you recently switched to a new domain and want to ensure everything is set up correctly;
• you need to understand why some pages open via HTTPS while others do not.

2. How to quickly check HTTPS and the certificate in the browser's address bar

The quickest way is to open the site and look at the address bar. If there is a lock icon before the address, that's a good sign, but not a final answer. The lock means the connection is secure, but the details still need to be checked.

Then proceed as follows:

1. Open the site in the browser.
2. Check if the address starts with https://.
3. Click on the lock icon next to the address.
4. Open the connection or certificate details.
5. Check for which domain the certificate was issued and who signed it.
6. Check the expiration date.

What exactly should raise a red flag? If the browser shows a strikethrough lock, the message 'not secure', a warning about an untrusted connection, or a message that the certificate does not match the domain, that is already a reason to stop. It's not worth 'clicking further because it's very important'. In such situations, it's better to first figure out what is wrong.

Also pay attention to the address itself. Sometimes scammers use an address that is very similar to the original: one extra letter, a strange hyphen, a different top-level domain. This is no longer a question of SSL per se, but this is where users most often make mistakes. For a general check of suspicious sites, our other material will also be useful — how to check a website for fraud.

3. How to check a website for an SSL certificate using browser tools

If you need a more precise answer, it's better to open the built-in browser tools. The path differs in different programs, but the logic is the same: find security information and view the certificate in full.

Chrome

In Chrome, click on the lock icon or the connection settings symbol to the left of the website address. A brief panel will open with information about whether the connection is secure. Usually, you can go to the certificate details from there. Look for fields such as certificate owner, certificate authority, validity period, and the domain it was issued for.

Firefox

In Firefox, click on the lock icon, then open additional information about the connection. The browser usually shows whether the authenticity of the site is confirmed, whether encryption is used, and if there are any remarks about the certificate. If you dig deeper, you can see the technical parameters of the certificate and the list of domains for which it is valid.

Safari

In Safari, click on the lock icon in the address bar, then open the certificate or connection information. On macOS, the details are sometimes not as clearly displayed as in Chrome or Firefox, but the necessary information is still available. Check who the certificate is issued to, when it expires, and if there are any system warnings.

What to look for in browser tools:

• the domain for which the certificate is issued;
• the start and end date of validity;
• the certificate authority;
• the type of connection and the presence of encryption;
• warnings about incorrect installation.

If the site looks fine overall, but there is an error in the technical details, do not ignore it. Sometimes it's just a misconfigured server. Other times, it's a signal that the site is trying to use an old or fake certificate.

4. How to check a site's SSL certificate through online services

Online services are convenient when you need to quickly check a website not only in your own browser but also through an external tool. This approach helps to see how the certificate is perceived from the outside: whether the chain of trust is correct, if there are any issues with intermediate certificates, and if the host name matches.

The secure scenario is simple: just enter the address of the site you want to check into the service. There is no need to enter passwords, personal data, or admin access. The service usually then shows a technical report where you can see the expiration date, issuer, supported domains, and possible installation errors. If the service asks you to upload a file or behaves strangely, it's better to close the page and choose another tool.

What is useful to check in the results:

• does the certificate match the required domain;
• has the expiration date passed;
• are the intermediate certificates installed correctly;
• is an outdated algorithm not being used;
• are there any warnings about incompatibility or an incomplete chain.

It is important not to focus on just one indicator. Sometimes the service states that the certificate is valid, but the trust chain is incomplete. For the user, this can result in a browser warning. Therefore, always look at the bigger picture, not just one green checkmark.

5. What to pay attention to when checking: validity period, domain, trust chain

In short, a good SSL certificate must match three things: the domain, the validity period, and trust in the certification authority. In practice, this is usually enough to eliminate most problems.

Check the domain. A certificate issued for example.com is not automatically valid for www.example.com unless specified in its settings. Similarly, a certificate for a subdomain may not cover the entire main site. This is why there are cases where the main page opens without errors, but one of the internal pages shows a warning.

The validity period is also critical. An expired certificate is usually considered invalid by the browser. Externally, the site may be fully functional, but trust in it drops immediately. If you are the resource owner, you should not wait until the last day. If you are a user and the certificate has already expired, it is better not to enter any data until the issue is resolved.

The certification center also matters. The browser does not trust just any publisher, but only verified centers. If the certificate is signed by an unknown publisher or the chain of trust is broken, the connection may be considered unsafe. Sometimes the error arises not from the certificate itself, but because the server does not return the intermediate file. For the user, this looks equally unpleasant, but for the administrator, the solution will be different.

Another important point is the installation. Even a correct certificate may not work properly if the files on the server are mixed up, the wrong redirects are set, or mixed resources are connected. This means that the page loads over HTTPS, but part of the images, scripts, or styles is pulled in over regular HTTP. Then the browser starts warning about mixed content.

6. How to understand that the certificate is installed incorrectly or the site is unsafe

There are several signs that almost always indicate a problem. If you see at least one of them, it is worth approaching the site with caution.

• There is no lock icon, and the address starts with http://.
• The browser says 'not secure' or shows a red warning.
• Name error: the certificate was issued for the wrong domain.
• The certificate has expired.
• The publisher is not recognized as trusted.
• The page opens over HTTPS, but there is mixed content inside.
• The site constantly redirects between http and https.

Especially unpleasant is the scenario when the site seems to open, but the browser hides some warnings until data is entered. Externally, everything seems calm, but technically the connection is already not perfect. In such a situation, it's better to double-check the address, open the tab with the certificate, and not rush with authorization.

If you want to look at the issue of fraud more broadly, it's useful not only to check the certificate but also to compare it with other signs. For example, a legitimate project usually has clear contacts, a understandable structure, and predictable pages. A questionable site often relies on one bright screen and an urgent call to 'act now.'

7. What to do if the site's SSL certificate is not working or has expired

If you are a user and not the website owner, your actions are simple: do not enter personal information, try to open the site later, and inform the owners about the problem if appropriate. Sometimes the error is temporary, especially if the certificate was just updated and the server has not yet picked up the changes.

If you are administering the site, the usual course of action is as follows:

1. Check if the certificate has indeed expired.
2. Make sure that the current certificate and key file are installed on the server.
3. Check the trust chain and intermediate certificates.
4. Set up a redirect from http to https.
5. Check for mixed content on the pages.
6. Open the site in several browsers and recheck HTTPS and the certificate.

Sometimes the problem lies not in the certificate, but in the configuration of the web server or CDN. It may seem that everything is set up correctly, but the browser continues to complain. In such cases, a sequential check helps: first the address, then the certificate details, then external validation, and finally retesting after corrections.

If the site has moved to a new domain or you changed hosting, make sure that old addresses correctly redirect to the HTTPS version. Users should not go through a chain of dubious or outdated redirects. The shorter the path to the secure page, the better.

8. Short checklist for checking a website for SSL certificate

If you need to quickly check a website, here is a short algorithm. It is suitable for both regular users and resource owners.

• Open the website via HTTPS.
• Check for the lock icon in the address bar.
• Verify the domain in the address and the domain in the certificate.
• Check the validity period of the certificate.
• Ensure that the certificate authority is trusted.
• Check for warnings about mixed content or untrusted connections.
• If in doubt, recheck the site using browser tools or an online service.

The main idea is simple: an SSL certificate should be checked thoughtfully, not just formally. One lock does not guarantee that everything is perfect, but the absence of a lock or obvious errors is already a serious signal. In practice, this takes just a few minutes, but it helps avoid unpleasant surprises when it comes to money, personal data, or the reputation of the site. And this is exactly the case when a few extra clicks pay off in peace of mind.