CertCheck

What the server sends. What your machine believes.

A free Windows app that inspects any TLS/SSL certificate and tells you whether this machine trusts it — and if not, exactly why.

Download for Windows

or download the portable .zip — no installation, just unzip & run

Windows 10 / 11 · .NET Framework 4.8 · Free

SHA-256 · CertCheck.msi 7f2a696ac0764777524b3f5b277908729b9f301f91f484202df6180cc8de0638

SHA-256 · CertCheck-portable.zip 7b506945434b53d24b1fd2be9a1b6bd368468353cad606663d25bace59aedfee

See exactly what a server sends — and whether you trust it

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Instant Trust Verdict

Fetches the live certificate over TLS (with SNI) and gives a plain green / amber / red verdict: trusted, trusted-but-flawed, or unknown to this machine.

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Why Is It Trusted?

Walks the full certificate chain to its root and shows exactly which store on this machine anchors the trust — or where the chain breaks.

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Compare to Local Store

When the same certificate also lives in a local Windows store, view both side by side with every difference and expiry highlighted.

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SAN Reachability

Checks each Subject Alternative Name, resolving it from this machine and flagging short, unqualified names that only work on internal networks.

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Files, Export & Reports

Load a .cer / .crt / .pem from disk, export the fetched certificate, or generate a printable, machine-stamped HTML report.

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Runs Locally

Everything runs on your machine against your own trust stores. Optional online revocation checking is the only step that touches the network — and only when you ask.