Enter a domain to check
Supports custom ports — e.g.mysite.com:8443
// verify ssl certificates and tls config in one click
Check any domain's SSL certificate instantly. View expiry date, issuer, cipher suite, and TLS version. Free, browser-based, no sign-up required.
Enter a domain to check
Supports custom ports — e.g.mysite.com:8443
Type or paste any domain name. Add a custom port with domain.com:8443 if needed.
The tool connects to the server and retrieves the live certificate in real time.
See expiry, issuer, TLS version, cipher suite, SANs, and full certificate metadata.
The SSL Checker connects directly to your domain over port 443 (or a custom port) and retrieves the live SSL/TLS certificate. It parses and displays all certificate metadata — expiry date, issuer chain, cipher suite, key type, and all SANs — without requiring any browser extension or local software.
Yes, completely free. No sign-up, no API key, no rate limits for normal use. The tool runs a server-side connection to your domain and returns results instantly.
Yes. Enter the domain followed by a colon and port number — for example, myapp.com:8443. This is useful for staging servers or applications not running on the default HTTPS port 443.
It shows how many days remain until the SSL certificate expires. When this reaches zero the certificate becomes invalid and browsers will show a security warning to your visitors. Most certificates are renewed when fewer than 30 days remain.
SANs list every hostname the certificate covers. A wildcard cert like *.example.com covers all subdomains, while a multi-domain cert may list dozens of separate hostnames. This tool displays all SANs found in the certificate.
This can happen if the domain on the certificate does not match the domain you entered, the certificate chain is incomplete, the certificate has expired, or a self-signed certificate is in use. The error message shown will indicate the specific reason.
The checker reports the TLS version negotiated during the connection — typically TLS 1.2 or TLS 1.3. TLS 1.3 is preferred as it offers better security and performance. Older versions like TLS 1.0 and 1.1 are deprecated.
No data is stored. The check is performed in real time, results are returned to your browser, and no certificate data, domain names, or results are logged or retained on our servers.
No. The check is performed from our server, not your local machine, so it can only reach publicly accessible domains. For internal servers you would need a local tool like OpenSSL's s_client command.
An SSL Certificate Checker is an online tool that connects to a web server and retrieves its SSL/TLS certificate in real time, parsing all the technical details into a human-readable report. Instead of diving into browser developer tools or running OpenSSL commands in a terminal, you can paste a domain name and instantly see the certificate's validity status, expiry date, issuer information, the list of covered hostnames, the TLS protocol version in use, and the cipher suite negotiated during the handshake.
SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are the cryptographic protocols that secure connections between browsers and web servers. The small padlock icon you see in the browser address bar indicates an active TLS connection backed by a valid certificate. When that certificate expires, is misconfigured, or does not match the domain name, browsers display security warnings that drive visitors away and hurt search engine rankings.
Certificate expiry is one of the most common and preventable causes of website outages and trust warnings. Certificate Authorities (CAs) issue SSL certificates with a limited validity period — typically 90 days for certificates from services like Let's Encrypt, or up to 13 months for commercially purchased certificates. Once a certificate expires, every visitor to the site receives a browser warning stating the connection is not secure, which immediately damages credibility and can cause a significant drop in traffic and conversions.
Beyond expiry, certificate misconfigurations cause equally disruptive problems. An incomplete certificate chain (missing intermediate certificates), a certificate that does not cover the exact domain or subdomain being accessed, or a certificate issued by an untrusted CA can all trigger browser errors even when the certificate itself has not expired. Proactively checking SSL configuration before and after deployments is an essential part of any professional DevOps or web development workflow.
Subject and Common Name (CN): The Subject field identifies who the certificate was issued to. The Common Name (CN) historically contained the primary domain the certificate covers. Modern certificates use Subject Alternative Names instead, but the CN still appears in the subject field and typically matches the primary domain.
Issuer: The Issuer identifies the Certificate Authority (CA) that signed and vouches for the certificate. Well-known CAs include DigiCert, Sectigo, Let's Encrypt, GlobalSign, and Entrust. Browsers maintain a built-in list of trusted root CAs; certificates signed by an unknown or self-signed authority will be flagged as untrusted.
Subject Alternative Names (SANs): SANs list every hostname the certificate is valid for. A wildcard certificate like *.example.com covers all direct subdomains such as www.example.com, api.example.com, and blog.example.com but not deeper subdomains like app.staging.example.com. Multi-domain (SAN) certificates can list dozens of completely different hostnames, making them efficient for organizations managing many domains with a single certificate.
TLS Version: The TLS version field reports which version of the Transport Layer Security protocol was negotiated during the connection. TLS 1.3, released in 2018, is the current recommended standard — it is faster and more secure than its predecessors. TLS 1.2 is still widely supported and considered secure. TLS 1.0 and TLS 1.1 are deprecated and should be disabled; modern browsers reject connections using these older versions.
Cipher Suite: The cipher suite describes the combination of algorithms used for key exchange, authentication, encryption, and message integrity during the TLS session. Examples include TLS_AES_256_GCM_SHA384 (TLS 1.3) and ECDHE-RSA-AES128-GCM-SHA256 (TLS 1.2). Strong cipher suites using AES-GCM, ChaCha20-Poly1305, and ECDHE key exchange are preferred over older options using RC4 or 3DES, which have known vulnerabilities.
Key Type and Bit Length: SSL certificates use either RSA or EC (Elliptic Curve) public keys. RSA 2048-bit is the minimum recommended key length for RSA certificates; RSA 4096-bit offers stronger security. EC certificates (ECDSA) using 256-bit or 384-bit keys offer equivalent or better security than RSA 2048/4096 with smaller key sizes and faster handshakes.
Using the tool is straightforward. Enter any publicly accessible domain name in the input field — just the hostname, with or without https://. If the server runs HTTPS on a non-standard port, append the port number after a colon, for example staging.myapp.com:8443. Click the Check SSL button and within a few seconds the tool will display a full certificate report including the validity status, expiry countdown, issuer details, all SANs, TLS version, and cipher suite.
The color-coded status banner at the top of the results immediately communicates the certificate's health. Green indicates a valid certificate with ample time remaining. Yellow signals the certificate will expire within 30 days. Red warns of imminent expiry (under 14 days) or an already-expired certificate. Orange indicates a certificate that could not be fully validated — this might happen with self-signed certificates or incomplete chains.
Developers comfortable with the terminal often use OpenSSL's s_client command to inspect certificates directly: openssl s_client -connect example.com:443 -servername example.com. This is powerful but outputs a wall of raw text that requires parsing. The SSL Checker provides the same information in a structured, visual format that is faster to scan and share with non-technical stakeholders. The Copy Full Report button exports a complete JSON object with all certificate details for integration into monitoring scripts or documentation.
Rather than checking certificates manually, teams running production services should set up automated certificate monitoring. Many services and server monitoring tools support SSL expiry alerts. A common workflow is to trigger an alert when fewer than 30 days remain on a certificate, giving time to renew before any disruption occurs. For certificates managed via Let's Encrypt, automatic renewal through Certbot or ACME clients eliminates manual renewal entirely, though it is still good practice to verify that auto-renewal is functioning correctly.
When deploying to a new environment or after changing hosting providers, always run an SSL check immediately after DNS propagation to confirm the certificate is served correctly and the full chain is present. Missing intermediate certificates are a common source of SSL errors that do not appear in local browser testing (which often caches intermediate certificates) but affect first-time visitors on different devices.