Verify SSL/TLS certificate validity, expiry date, issuer, and security details for any domain.
This free SSL certificate checker lets you instantly verify the SSL/TLS certificate status for any publicly accessible website domain — checking validity, expiration date, the issuing Certificate Authority, and key security details, all in real time with no registration required. Whether you manage your own website, are auditing a client's site, or simply want to verify that a site you're about to use is genuinely secured with a valid certificate, this tool delivers a complete certificate overview in seconds.
SSL certificate monitoring is one of the most overlooked aspects of website maintenance. Certificate expiry is entirely preventable — yet it continues to cause major outages and trust damage for thousands of websites every day. In 2024, major organisations including financial institutions, government agencies, and enterprise SaaS products all suffered SSL expiry incidents that blocked user access and generated headlines. The damage is always disproportionate to the simple, low-cost fix of renewing the certificate on time.
This checker works by querying the SSL handshake of the target domain in real time, reading the certificate's metadata, and presenting the results in a clear, actionable format. No installation, no command-line knowledge, and no technical background required — just enter a domain and click Check.
Type the domain you want to check
into the input field — for example, google.com or
ourtoolkit.online. You can include or omit the https:// prefix;
the tool strips it automatically. Subdomains are supported — enter
mail.example.com to check a subdomain's specific certificate separately from
the root domain's.
The tool connects to the domain over HTTPS and reads the SSL certificate presented by the server. This is the same process your browser performs every time you visit an HTTPS website — we simply extract and present the certificate metadata in a readable format. Results typically appear within 2–4 seconds depending on the target server's response time.
Results include the certificate validity status (Valid / Expiring Soon / Expired), exact expiration date, number of days remaining, the issuing Certificate Authority, and the domain(s) the certificate is valid for. A visual days-remaining bar shows at a glance how close the certificate is to expiry. A red status banner appears immediately for expired or critically close-to-expiry certificates.
If the certificate shows Valid with 60+ days remaining, no immediate action is needed — note the expiry date for your renewal calendar. If it shows Expiring Soon (under 30 days), schedule renewal immediately. If Expired, treat it as an urgent outage — renew the certificate and redeploy as your highest priority. Copy results with one click to share with your hosting team or include in a security report.
The tool performs a live HTTPS handshake with the target domain, reading the actual certificate currently being served. This means results always reflect the current state — if a certificate was just renewed or just expired minutes ago, the tool shows the current status accurately, unlike tools that rely on periodically cached databases.
The exact expiration date and a precise days-remaining count give you immediate clarity on urgency. A visual progress bar shows the certificate's position in its validity lifecycle. Certificates under 30 days from expiry trigger an amber warning; expired certificates trigger a red alert banner — no ambiguity about what action is required.
The issuing Certificate Authority (CA) is identified — Let's Encrypt, DigiCert, Sectigo, GlobalSign, Comodo, and others. Knowing the CA helps with renewal: Let's Encrypt certificates require different renewal processes than commercially purchased certificates. The CA name also helps verify that the certificate is from a trusted, browser-recognised authority.
Check any publicly accessible domain or subdomain independently. A wildcard certificate covering *.example.com may have a different expiry date from a separate certificate on a specific subdomain. Checking subdomains individually — mail.example.com, api.example.com, shop.example.com — ensures no part of your infrastructure has a quietly expiring certificate.
One-click copy exports all certificate details as formatted text, ready to paste into a security audit report, a Slack message to your hosting team, a support ticket, or a project management task. No manual transcription of dates and issuer names required.
Fully responsive on iPhone, Android, tablet, and desktop browsers. Check a client's SSL certificate from your phone during a meeting, or audit a portfolio of sites from desktop. No app installation or browser extension required — the full tool works in any modern browser.
| Status | Days Remaining | What It Means | Action Required | Urgency |
|---|---|---|---|---|
| ✅ Valid | 60+ days | Certificate is current, valid, and not close to expiry | Note expiry date; set renewal reminder | None |
| ⚠️ Renew Soon | 30–59 days | Certificate valid but renewal window is approaching | Begin renewal process this week | Low–Medium |
| 🔶 Expiring Soon | 1–29 days | Certificate nearing critical expiry threshold | Renew immediately — do not delay | High |
| 🔴 Expired | 0 (past expiry) | Certificate has expired — browsers block or warn visitors | Emergency renewal — treat as live outage | Critical |
| ❌ Invalid | N/A | Certificate domain mismatch or untrusted issuer | Replace with correct certificate | Critical |
| 🚫 No HTTPS | N/A | Domain does not have an SSL certificate installed | Install SSL certificate; redirect HTTP to HTTPS | High |
An SSL certificate (technically a TLS certificate in modern usage — the SSL term persists as legacy shorthand) is a digital document that serves two primary functions: it authenticates the identity of a website (confirming you are connected to the genuine server, not an impostor), and it enables encrypted communication between the user's browser and the web server using public-key cryptography.
When a browser connects to an HTTPS website, the server presents its SSL certificate as part of the TLS handshake. The browser verifies the certificate is signed by a trusted Certificate Authority (CA) in its trust store, that the certificate is not expired, and that the domain name matches. If all checks pass, an encrypted session is established and the padlock icon appears in the address bar. The entire verification process takes milliseconds and is invisible to the user.
The TLS handshake is the process by which a browser and server establish an encrypted connection. In TLS 1.3 (the current standard), the handshake requires just one round trip: the browser sends a "ClientHello" message advertising its supported TLS versions and cipher suites. The server responds with its certificate, its chosen cipher suite, and the parameters for key exchange. The browser verifies the certificate, and both parties derive symmetric encryption keys from the key exchange. All subsequent communication is encrypted with those keys. The entire handshake typically takes 20–100 milliseconds on a fast connection.
A Certificate Authority (CA) is an organisation trusted by browsers and operating systems to sign SSL certificates. When a CA signs a certificate, it is asserting that it has verified the applicant's right to use the domain (and, for OV/EV certificates, the applicant's organisational identity). Browsers and operating systems maintain a trust store — a list of root CA certificates they consider trustworthy. A certificate signed by an untrusted CA generates a browser warning.
The major commercial CAs include DigiCert (which owns Symantec, GeoTrust, and Thawte brands), Sectigo (formerly Comodo CA), GlobalSign, and Entrust. The non-profit Let's Encrypt, operated by the Internet Security Research Group, has become the world's largest CA by volume since its launch in 2016, having issued billions of free DV certificates and making HTTPS accessible to every website regardless of budget.
Domain Validation (DV) certificates are the most common type. The CA verifies only that the applicant controls the domain — typically by placing a specific file on the web server or adding a DNS record. DV certificates are issued in minutes, cost nothing (with Let's Encrypt) to a few dollars per year, and are appropriate for blogs, portfolios, and any site where identity verification of the organisation isn't required by users. The encryption they provide is identical to OV and EV certificates.
Organisation Validation (OV) certificates require the CA to verify both domain control and the legal existence of the applying organisation. The CA checks business registration records, may call the organisation to verify, and confirms that the person requesting the certificate is authorised to represent the organisation. OV certificates are appropriate for business websites where users may want confidence that the site belongs to a real, verified company. The organisation name appears in the certificate's Subject field.
Extended Validation (EV) certificates require the most rigorous vetting process, including verification of legal existence, physical address, operational status, and identity of the certificate applicant. Prior to 2019, major browsers displayed the organisation name in a green bar in the address bar for EV certificates — a highly visible trust indicator. Google Chrome and other browsers removed this visual distinction in 2019, citing research showing users didn't reliably understand its meaning. EV certificates still contain more detailed organisational information and are used by financial institutions and enterprises where maximum identity assurance is valued.
SSL (Secure Sockets Layer) was the original encryption protocol developed by Netscape in the mid-1990s. SSL 2.0 was released in 1995, and SSL 3.0 in 1996. Both versions were found to have serious security vulnerabilities — SSL 3.0 was vulnerable to the POODLE attack — and both were officially deprecated by the IETF (Internet Engineering Task Force). TLS (Transport Layer Security) was introduced as SSL's replacement with TLS 1.0 in 1999, followed by TLS 1.1 (2006), TLS 1.2 (2008), and TLS 1.3 (2018).
Modern websites use TLS 1.2 or TLS 1.3. TLS 1.3 provides significant improvements: faster handshakes (one round trip vs two), forward secrecy by default, removal of weak and legacy cryptographic algorithms, and improved resistance to downgrade attacks. Despite the technical distinction, "SSL certificate" remains the universal industry term for TLS certificates because "SSL" entered common usage before the TLS rebrand and has never been replaced in everyday language.
Certificate Transparency (CT) is an open framework introduced by Google in 2013 and now required by all major browsers for public trust. Every SSL certificate issued by a publicly trusted CA must be logged in at least two publicly accessible Certificate Transparency logs before browsers will trust it. These logs are append-only — entries can never be deleted or modified, creating a permanent, auditable record of every certificate ever issued.
CT makes it possible for domain owners to monitor what certificates have been issued for their domains. Tools like crt.sh provide free CT log search — entering a domain name shows every certificate ever issued for it, including certificates you didn't authorise. This is a powerful security tool: if a malicious actor tricks a CA into issuing a fraudulent certificate for your domain, CT makes it discoverable.
Every website owner who cares about their site's availability needs to monitor their SSL certificate. An expired certificate is a complete, immediate barrier to visitor access — browsers don't just warn users, they actively prevent navigation with a full-page error that most users cannot bypass and won't try to. The impact is immediate: zero traffic, zero conversions, zero revenue from the affected domain until the certificate is renewed and propagated.
The frustrating reality is that SSL expiry is entirely preventable. The only reason it happens is that renewal reminders are missed — they go to old email addresses, get buried in spam, or nobody has responsibility for monitoring. A simple monthly SSL check, or a calendar reminder 45 days before expiry, eliminates the risk entirely.
Web development agencies managing multiple client websites have a professional obligation to monitor SSL certificates for all sites under their management. An unexpected SSL expiry on a client site is a relationship-damaging event that reflects poorly on the agency, regardless of whether the client was responsible for managing their own hosting. Proactive SSL monitoring and renewal management is a standard value-add service offered by professional agencies.
Developers also need to check SSL certificates during site migrations, hosting changes, and CDN configuration. After pointing a domain to a new server, verifying the SSL certificate was correctly transferred and is functioning is a critical step in the post-migration checklist. A certificate that was valid on the old server is not automatically valid on the new one — a new certificate must be installed.
Information security teams conduct regular SSL certificate audits as part of their security posture management. This involves inventorying all certificates across all domains and subdomains, checking for certificates nearing expiry, identifying certificates using deprecated algorithms (SHA-1, RSA-1024), verifying that only approved Certificate Authorities are used, and confirming TLS version support meets current standards (TLS 1.2 minimum; TLS 1.3 preferred).
Compliance frameworks including PCI DSS (for payment card industry), SOC 2, ISO 27001, and HIPAA (healthcare) all include requirements for secure transport encryption. SSL/TLS certificate validity and configuration is a standard audit item in all of these frameworks. An expired or misconfigured SSL certificate discovered during a compliance audit can result in findings that delay certification.
Media literacy increasingly requires verifying the legitimacy of websites, particularly when sources are shared on social media or arrive via unfamiliar links. While an SSL certificate doesn't confirm a website's content is trustworthy (phishing sites can and do use SSL certificates — DV certificates require no identity verification), an expired or absent SSL certificate on a site claiming to be a legitimate organisation is a significant credibility red flag worth investigating.
Security-conscious online shoppers check SSL certificates before entering payment information on unfamiliar websites. Verifying that a site has a valid SSL certificate, identifying its Certificate Authority, and checking its expiry date takes seconds with this tool. While an SSL certificate alone doesn't guarantee a site is legitimate (it only guarantees encrypted transit), an absent, expired, or self-signed certificate on a checkout page is a definitive reason not to proceed with a purchase.
| Problem | Browser Error | Cause | Fix |
|---|---|---|---|
| Expired certificate | NET::ERR_CERT_DATE_INVALID | Certificate past its validity period | Renew certificate via your CA or hosting panel |
| Domain mismatch | NET::ERR_CERT_COMMON_NAME_INVALID | Certificate issued for different domain | Issue new certificate matching the correct domain |
| Self-signed certificate | NET::ERR_CERT_AUTHORITY_INVALID | Certificate not signed by trusted CA | Replace with CA-signed certificate (free via Let's Encrypt) |
| Incomplete chain | NET::ERR_CERT_AUTHORITY_INVALID | Intermediate CA certificates missing | Install full certificate chain including intermediates |
| Mixed content | Padlock with warning triangle | HTTPS page loading HTTP resources | Update all resource URLs to HTTPS |
| HTTP not redirecting | No padlock on HTTP version | Missing 301 redirect from HTTP to HTTPS | Add permanent redirect in server config or .htaccess |
| Weak cipher | Browser connection warning | Server using deprecated TLS or cipher | Disable TLS 1.0/1.1; configure strong cipher suites |
| Method | Speed | Detail Level | Technical Skill | Mobile-Friendly | Share Results |
|---|---|---|---|---|---|
| This Tool | ✅ Instant | ✅ Full details | ✅ None needed | ✅ Yes | ✅ Copy button |
| Browser padlock click | ✅ Instant | ⚠️ Basic only | ✅ Minimal | ⚠️ Awkward | ❌ Screenshots only |
| openssl s_client | ✅ Fast | ✅ Full raw output | ❌ Expert only | ❌ CLI only | ❌ Manual copy |
| SSL Labs (ssllabs.com) | ⚠️ 1–2 minutes | ✅ Very detailed | ✅ None needed | ✅ Yes | ✅ Shareable URL |
| Hosting control panel | ✅ Fast | ⚠️ Basic | ✅ Minimal | ⚠️ Varies | ❌ No |
Let's Encrypt certificates are valid for only 90 days. Without auto-renewal configured, you face certificate expiry every three months. Most modern hosting platforms (cPanel, Plesk, Nginx with Certbot) support automated Let's Encrypt renewal — ensure this is properly configured and periodically verify it's working. A certificate that auto-renewed successfully appears valid in this checker; one where auto-renewal failed shows as expiring or expired.
A wildcard certificate covering *.example.com does not cover the root domain example.com — it requires a separate certificate entry. Similarly, a certificate for www.example.com doesn't cover api.example.com. Each subdomain serving HTTPS may have its own certificate with its own expiry date. Check all subdomains independently, especially those that accept logins or payments.
Certificate renewal reminders go to the email address in the certificate's registration. This is often a technical contact from years ago, a role-based email like admin@domain.com that nobody checks, or an email account that was deleted when the original developer left. Set calendar reminders independent of email, and update contact information when staff change.
After renewing or replacing a certificate, always verify the new certificate is being served correctly by running a fresh check in this tool. Common post-renewal issues include: the wrong certificate being active if there are multiple certificates on the server, intermediate certificates not being installed causing chain validation failures, and CDN caches serving old certificate data before propagation completes.
Internal tools, admin panels, and staging environments without SSL certificates create real security risks even on private networks. Credentials transmitted over plain HTTP on an internal network can be intercepted by anyone on the same network — including other devices infected with malware. Use SSL even for internal tools. Let's Encrypt certificates require public domain validation, but private CAs or self-signed certificates with proper installation are acceptable for genuinely internal services.
SSL certificates verify the encrypted connection, not the legitimacy of the site's content or intentions. Phishing sites routinely obtain valid DV SSL certificates — getting a free Let's Encrypt certificate requires only domain control, not identity verification. A padlock icon means your connection to the site is encrypted; it does not mean the site is legitimate, safe, or operated by who they claim to be. Always verify the full domain name in the address bar.
An SSL/TLS certificate authenticates a website's identity and enables encrypted HTTPS communication. Websites need SSL to protect user data in transit, display the browser padlock, rank in Google search results (HTTPS is a confirmed ranking factor), meet PCI DSS requirements for payment processing, and avoid Chrome's "Not Secure" warning. Without SSL, any data a user submits — login credentials, payment details, personal information — can be intercepted in transit.
Enter the domain name above and click Check Certificate. The tool performs a live HTTPS query and returns the current validity status, expiration date, issuing CA, and days remaining. You can also check in any browser by clicking the padlock icon in the address bar, selecting Certificate or Connection is secure, and reading the certificate's validity dates.
Browsers display a full-page security warning — Chrome shows "Your connection is not private", Firefox shows "Warning: Potential Security Risk Ahead", Safari shows "This Connection is Not Private". Most users abandon the site at this point. The site continues to function technically, but is effectively inaccessible to most visitors. Revenue, traffic, and reputation damage begin immediately. Renew the certificate and redeploy as an emergency priority.
DV (Domain Validation) verifies only domain control — issued in minutes, free via Let's Encrypt. OV (Organisation Validation) also verifies the organisation's legal existence — requires documentation, takes hours to days. EV (Extended Validation) requires the most rigorous business verification — the highest assurance level. All three provide identical encryption strength. The difference is the level of identity verification and what information appears in the certificate's Subject field.
The maximum validity period is 398 days (roughly 13 months) as mandated since September 2020. Let's Encrypt certificates are valid for 90 days. Best practice is to renew at least 30 days before expiry. Google is actively proposing reducing the maximum to 90 days, which would make automated renewal mandatory for all certificates. Configure auto-renewal wherever your hosting infrastructure supports it.
Let's Encrypt is a free, non-profit Certificate Authority that has issued billions of DV certificates since 2016. Cryptographically, Let's Encrypt certificates are identical in security to paid DV certificates — the same algorithms, the same key lengths, the same browser trust. The only differences are the 90-day validity period (vs 12 months for paid), the issuer name, and the absence of OV/EV options. For most websites, Let's Encrypt is the optimal choice: free, automated, and fully secure.
TLS (Transport Layer Security) is the modern, secure successor to SSL. All SSL versions are deprecated due to security vulnerabilities. Modern websites use TLS 1.2 or TLS 1.3. "SSL certificate" persists as industry shorthand even though the actual protocol is TLS. TLS 1.3 provides faster handshakes, forward secrecy by default, and eliminates legacy vulnerable cryptographic algorithms. When you see "SSL" anywhere in modern documentation, it means TLS in practice.
Yes. Google confirmed HTTPS as a ranking signal in 2014. Sites without valid SSL certificates are marked "Not Secure" in Chrome, increasing bounce rate and damaging user engagement metrics that also influence rankings. HTTPS is effectively a baseline requirement for search visibility — it won't boost you above competitors on its own, but its absence creates meaningful disadvantages. All new websites should be launched on HTTPS from day one.
A wildcard certificate secures a domain and all its first-level subdomains with one certificate, using an asterisk: *.example.com covers www.example.com, mail.example.com, blog.example.com etc. It does not cover sub-subdomains (dev.api.example.com) or the root domain example.com itself without a separate SAN entry. Wildcard certificates simplify management for organisations with multiple subdomains.
Certificate Transparency (CT) is a mandatory framework requiring all CAs to log every issued SSL certificate in publicly auditable append-only logs. Chrome requires CT compliance for all trusted certificates. CT allows domain owners to monitor what certificates have been issued for their domains via tools like crt.sh — detecting any fraudulent or unauthorised certificates issued by a compromised CA. It is a critical component of the public CA trust infrastructure.