TLS Certificate Auditor

Connects to any public host over TLS and audits its certificate posture in one API call. Checks validity dates and days until expiry, hostname and Subject Alternative Name matching, chain completeness and trust status, negotiated protocol and cipher, and public key strength. Returns a readiness score, letter grade, issues, and recommendations as structured JSON.

Use cases

• DevOps and platform teams monitoring certificate expiry across endpoints and catching renewals that silently fail
• Security teams auditing chain completeness, self-signed certificates, weak keys, and deprecated TLS protocol versions
• Site migration QA verifying that every endpoint serves the right certificate for its hostname after a cutover
• Agency consultants running recurring certificate posture checks across client domains
• CI pipelines gating deployments on certificate regressions

Input

Field	Type	Default	Description
startUrl	string	(required)	Public HTTPS URL or bare hostname to audit. The actor opens one TLS connection to this host on port 443 (or the URL port) and inspects the served certificate chain.
timeoutSeconds	integer	10	TLS connection timeout, from 3 to 30 seconds.
expiryWarningDays	integer	30	Flag the certificate as expiring soon when it expires within this many days.

Output

One dataset item per run:

Field	Type	Description
inputUrl	string	URL as provided in the input.
normalizedInputUrl	string or null	URL after scheme normalization and validation.
host	string	Hostname that was audited.
port	integer or null	TLS port used (443 or the URL port).
ok	boolean	Whether the audit completed without a connection or validation error.
checkedAt	string	ISO 8601 timestamp of the check.
connected	boolean	Whether the TLS connection was established.
authorized	boolean	Whether the served chain is trusted by standard root stores.
authorizationError	string or null	Node trust validation error, when the chain is not authorized.
subjectCommonName	string or null	Leaf certificate subject common name.
issuerCommonName	string or null	Leaf certificate issuer common name.
issuerOrganization	string or null	Leaf certificate issuer organization.
subjectAltNames	array	DNS Subject Alternative Names on the leaf certificate.
hostnameMatch	boolean	Whether the audited hostname matches the certificate SAN list or CN.
matchedCertificateName	string or null	The SAN or CN entry that matched.
validFrom	string or null	Certificate validity start, ISO 8601.
validTo	string or null	Certificate expiry, ISO 8601.
daysUntilExpiry	integer or null	Whole days from now until expiry (negative when expired).
expiryStatus	string	One of: valid, expiring-soon, expired, not-yet-valid, unknown.
expired	boolean	Whether the certificate is currently expired.
expiringSoon	boolean	Whether the certificate expires within the configured warning window.
fingerprint256	string or null	SHA-256 fingerprint of the leaf certificate.
serialNumber	string or null	Leaf certificate serial number.
keyType	string or null	Public key type (RSA or EC).
keyBits	integer or null	Public key size in bits.
weakKey	boolean	Whether the public key is below the recommended strength for its type.
protocol	string or null	Negotiated TLS protocol version (for example TLSv1.3).
cipherName	string or null	Negotiated cipher suite.
cipherVersion	string or null	Cipher version reported by the TLS stack.
weakCipher	boolean	Whether the negotiated cipher is a legacy or weak suite (NULL, RC4, 3DES, CBC-only).
chainDepth	integer	Number of certificates in the served chain.
chainSubjects	array	CN or organization of each certificate in the chain.
hasSelfSignedRoot	boolean	Whether the served chain ends in a self-signed root certificate.
selfSignedLeaf	boolean	Whether the leaf certificate itself is self-signed.
chainLikelyIncomplete	boolean	Whether the chain appears to be missing intermediate certificates.
score	integer	Certificate posture score from 0 to 100.
grade	string	Letter grade from A+ to F.
issues	array	Concrete problems found.
recommendations	array	Actionable fixes.
error	string or null	Error message when the audit could not complete.

Example input

{
    "startUrl": "https://www.wikipedia.org/",
    "timeoutSeconds": 10,
    "expiryWarningDays": 30
}

Example output

{
    "host": "www.wikipedia.org",
    "port": 443,
    "ok": true,
    "authorized": true,
    "subjectCommonName": "*.wikipedia.org",
    "issuerCommonName": "Sectigo RSA Domain Validation Secure Server CA",
    "subjectAltNames": ["*.wikipedia.org", "wikipedia.org"],
    "hostnameMatch": true,
    "matchedCertificateName": "*.wikipedia.org",
    "daysUntilExpiry": 200,
    "expiryStatus": "valid",
    "protocol": "TLSv1.3",
    "cipherName": "TLS_AES_256_GCM_SHA384",
    "keyType": "RSA",
    "keyBits": 2048,
    "weakKey": false,
    "weakCipher": false,
    "chainDepth": 3,
    "score": 100,
    "grade": "A+",
    "issues": [],
    "recommendations": [
        "Certificate posture looks good. Re-run daily or weekly to catch renewals that silently fail."
    ],
    "error": null
}

Security

• Connects to public hosts only; URLs with credentials are rejected.
• Private IPv4, private IPv6, and loopback targets are blocked, hostnames are DNS-resolved, and resolutions to private ranges are rejected (SSRF defense).
• One TLS connection per run to the validated host; no HTTP page content is fetched, no cookies are stored, no JavaScript is executed.
• Trust validation is performed and reported (authorized flag and trust error); deliberately broken certificates remain inspectable so the audit can explain exactly what is wrong.

Pricing

Event	Price
Actor start	$0.005 per run
Host audited	$0.01 per result

A typical single-host audit costs $0.015.

FAQ

Why would a certificate that browsers trust still fail the trust check? The actor validates the served chain against standard root stores the way a strict client does. If the server omits an intermediate certificate, some browsers can fill the gap from cached intermediates or built-in knowledge while strict clients cannot. The audit reports the incomplete chain so it can be fixed at the origin.

Does the actor fetch the website content? No. It opens a TLS connection and inspects the handshake and served certificate chain only, then closes the connection.

What counts as a weak key? RSA keys below 2048 bits and EC keys below 256 bits. Anything below the browser baseline (RSA 2048 or EC P-256) is flagged.

How should I use the expiry warning window? Set expiryWarningDays to match how long a renewal takes in your workflow (issuance, validation, CDN propagation). The default of 30 days fits ACME-automated setups; manual workflows may want 60 or more.