Website Security Certificate Checker API

API ID 13152

Inspect the security certificate of any host: issuer, subject, validity window, days remaining, expiry flags, alternative names, serial number, fingerprint, negotiated protocol and the full chain. Built for expiry monitoring and renewal alerts.

179 ms avg response

API Documentation

Endpoints

Request

Inspects the security certificate of the given host and returns issuer, subject, validity window, days remaining, expiry flags, alternative names, serial number, fingerprint, negotiated protocol and the certificate chain, as one structured response.

Endpoint ID: 26698
GET https://zylalabs.com/api/13152/website+security+certificate+checker+api/26698/check+certificate+of+a+host
INPUT PARAMETERS

Free test requests remaining: 3 of 3.


INPUT PARAMETERS

This endpoint does not require any input parameters.

API EXAMPLE RESPONSE
JSON
{"host":"google.com","port":443,"authorized":true,"authorization_error":null,"protocol":"TLSv1.3","alpn":"h2","subject_cn":"*.google.com","issuer":"Google Trust Services","valid_from":"Jun 22 08:35:23 2026 GMT","valid_to":"Sep 14 08:35:22 2026 GMT","days_remaining":65,"expired":false,"not_yet_valid":false,"serial_number":"AE068DC8BDF3E7570A0C6AFB39C2E9C5","fingerprint_sha256":"DC:53:B5:AD:68:0E:E4:41:6D:AC:DF:1A:CD:1F:59:2A:FA:78:43:B8:DC:D8:CB:63:98:E7:A9:7C:F9:DB:34:94","subject_alt_names":["*.google.com","*.appengine.google.com","*.bdn.dev","*.origin-test.bdn.dev","*.cloud.google.com","*.crowdsource.google.com","*.datacompute.google.com","*.google.ca","*.google.cl","*.google.co.in","*.google.co.jp","*.google.co.uk","*.google.com.ar","*.google.com.au","*.google.com.br","*.google.com.co","*.google.com.mx","*.google.com.tr","*.google.com.vn","*.google.de","*.google.es","*.google.fr","*.google.hu","*.google.it","*.google.nl","*.google.pl","*.google.pt","*.gemini.cloud.google.com","*.gstatic.com","*.metric.gstatic.com","*.gvt1.com","*.gcpcdn.gvt1.com","*.gvt2.com","*.gcp.gvt2.com","*.url.google.com","*.youtube-nocookie.com","*.ytimg.com","ai.android","android.com","*.android.com","*.flash.android.com","g.co","*.g.co","goo.gl","www.goo.gl","google-analytics.com","*.google-analytics.com","google.com","googlecommerce.com","*.googlecommerce.com","urchin.com","*.urchin.com","youtu.be","youtube.com","*.youtube.com","music.youtube.com","*.music.youtube.com","youtubeeducation.com","*.youtubeeducation.com","youtubekids.com","*.youtubekids.com","yt.be","*.yt.be","android.clients.google.com","*.aistudio.google.com"],"chain":[{"subject":"*.google.com","issuer":"WR2"},{"subject":"WR2","issuer":"GTS Root R1"},{"subject":"GTS Root R1","issuer":"GlobalSign Root CA"}]}
Check Certificate of a Host — CODE SNIPPETS

curl --location --request GET 'https://zylalabs.com/api/13152/website+security+certificate+checker+api/26698/check+certificate+of+a+host' --header 'Authorization: Bearer YOUR_API_KEY' 


    

API Access Key & Authentication

After signing up, every developer is assigned a personal API access key, a unique combination of letters and digits provided to access to our API endpoint. To authenticate with the Website Security Certificate Checker API simply include your bearer token in the Authorization header.

Headers
Header Description
Authorization Required Should be Bearer access_key. See "Your API Access Key" above when you are subscribed.

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Overview

Never let a certificate expire in production again. One call inspects the security certificate of any host and returns everything a monitoring pipeline needs.

  • Expiry at a glance: valid from, valid to, days remaining, plus expired and not-yet-valid flags
  • Trust verdict: whether the chain validates, with the exact error when it does not
  • Deep detail: subject, issuer, serial number, fingerprint, alternative names and the full chain
  • Handshake facts: the negotiated protocol version

Ideal for certificate expiry monitoring and renewal alerts, post-deploy checks in delivery pipelines, and auditing issuers across a domain portfolio. Expired or invalid certificates are still returned in full so you can diagnose them.

Website Security Certificate Checker API FAQs

The endpoint returns detailed information about a host's security certificate, including the issuer, subject, validity window, days remaining, expiry flags, alternative names, serial number, fingerprint, negotiated protocol, and the full certificate chain.

Key fields in the response include "host," "authorized," "valid_from," "valid_to," "days_remaining," "expired," "not_yet_valid," "serial_number," "fingerprint_sha256," and "subject_alt_names," providing comprehensive certificate details.

The response data is structured in JSON format, with key-value pairs representing various attributes of the security certificate. This allows for easy parsing and integration into monitoring systems.

The endpoint provides information on certificate validity, trust verification, detailed certificate attributes, and handshake protocol details, making it suitable for monitoring and auditing purposes.

Typical use cases include monitoring certificate expiry, setting up renewal alerts, conducting post-deployment checks in CI/CD pipelines, and auditing certificates across multiple domains for compliance.

Users can customize requests by specifying the host they want to inspect in the endpoint URL. This allows for targeted checks on specific domains or services.

Data accuracy is maintained through regular updates and checks against trusted certificate authorities, ensuring that the information returned reflects the current status of the security certificates.

Users can expect consistent data patterns, such as valid and expiry dates formatted in GMT, boolean flags for certificate status, and structured lists for alternative names, facilitating straightforward analysis and monitoring.

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