SSL/TLS Checker
A fully static, honest HTTPS and certificate checker.
Validate a domain, test whether HTTPS responds, and look up its certificate history in public Certificate Transparency logs — all from your browser, with no backend. Anything a static tool genuinely cannot verify is labelled as such rather than guessed.
The domain is checked from your browser and is not stored, put in the URL, or sent to our analytics.
What this tool can and cannot verify
This checker is fully static — it runs entirely in your browser with no server of its own. A browser cannot open a raw TLS connection to another site and read the certificate it presents, so the tool is deliberately honest about its limits rather than guessing.
Can check
- That the domain name you entered is syntactically valid, and its normalised form (scheme, path, and port stripped).
- Whether an HTTPS connection to the host can be established at all from your browser right now — a plain reachable / not-reachable signal.
- Optionally, the certificate history for the hostname from public Certificate Transparency logs (issuer, validity dates, and listed names of the most recently logged certificate) via a free third-party API you can choose to query.
Cannot check (shown as “Unable to verify”)
- The exact certificate the server is presenting right now — its issuer, serial, fingerprint, or expiry as served. A browser has no API to read the certificate of a cross-origin request, and this tool has no backend to do a TLS handshake for you.
- The negotiated TLS protocol version or cipher suite.
- Whether the certificate chain the server sends is complete and correctly ordered, or whether the root is trusted.
- Whether the hostname matches the live certificate (only whether it matches the most recent certificate seen in Certificate Transparency logs).
- OCSP stapling, HSTS, certificate revocation status in real time, or any HTTP security header — a cross-origin no-cors response exposes none of these.
About this SSL/TLS checker
This is a free SSL/TLS checker that runs entirely in your browser. Enter a domain and it validates the hostname, tests whether an HTTPS connection can be established, and — if you ask it to — looks up the domain’s certificate history in public Certificate Transparency logs. There is no server behind it, no account, and no paid API.
Because it is fully static, it is also honest about what it cannot see. A web page cannot open a raw TLS connection to another website and read the certificate that site presents — browsers deliberately do not expose that. So instead of guessing an issuer or an expiry date, this tool shows “Unable to verify” for anything it cannot genuinely determine. A smaller, truthful result is more useful than a confident wrong one.
What “reachable” means here
The reachability test sends a no-cors request to https:// your host. If it completes, the browser was able to open a TLS connection and make a request — that is all it tells you. It is not a statement that the certificate is valid, trusted, current, or correctly configured. If the request fails, the cause could be DNS, a refused connection, or a certificate problem such as an expired or mismatched certificate, and a static tool cannot tell those apart.
Certificate Transparency, and why it is not the live certificate
Every publicly trusted certificate is recorded in append-only Certificate Transparency (CT) logs. This tool can query those logs through a free public API and show you the most recently logged certificate for a hostname: its issuing CA, its validity window, and the names it covers. That is genuinely useful for spotting an upcoming expiry or an unexpected issuer.
But CT tells you what was issued, not what is served. The server might present an older certificate, a newer one that has not appeared in the logs yet (issuance can take hours to show up), or a certificate from a different CA entirely. Always confirm the certificate in your browser’s address bar for what a site is actually using.
For a full server-side test
To inspect the exact certificate a server presents — the chain, the negotiated TLS version and cipher, OCSP stapling, HSTS, and protocol/vulnerability checks — use a tool that performs a real TLS handshake from a server, such as Qualys SSL Labs, testssl.sh, or openssl s_client -connect host:443. This checker is for a quick, private, no-signup sanity check and an expiry heads-up from CT logs.
FAQ
Does this tool use a backend or a paid SSL API?
No. It is static HTML, CSS, and JavaScript. The only network calls are the reachability request to the host you enter and, if you click the button, a direct request from your browser to a free public Certificate Transparency search API. Nothing is proxied through our own infrastructure, and there is no API key.
Why can’t it show the certificate issuer or expiry date directly?
A browser has no API to read the certificate of a cross-origin request, and this tool has no server to perform a TLS handshake on your behalf. Rather than fake those fields, it labels them “Unable to verify” and offers the Certificate Transparency lookup as the closest honest substitute.
Is the domain I enter stored or logged?
No. It is not saved in your browser, not placed in the URL, and not sent to our analytics. The basic check contacts only the host you typed; the optional CT lookup sends the domain to the third-party CT search service, which is the purpose of that button.
The Certificate Transparency lookup said “rate limited”. Why?
The free CT search API allows only a few queries per hour per visitor with no account. If you hit that limit the tool shows “Unable to verify” for that section rather than inventing a result. Try again later.
Can it check an internal or IP-only host?
No. It needs a public domain name. IP addresses and localhost are rejected, and a host that is not reachable from the public internet will simply show as not reachable.
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