SSL Certificate Checker API

About the SSL Certificate Checker API

An SSL checker API and certificate verification API for expiry monitoring, domain audits and CI checks: send a hostname, get its live SSL certificate back as JSON. SSL Checker opens a real TLS connection to the site, reads the certificate and the chain the server sends, and validates it the way a client does (trusted root, hostname match, expiry), returning the verifier's error code such as CERT_HAS_EXPIRED or UNABLE_TO_VERIFY_LEAF_SIGNATURE when it fails. Alongside issuer, subject, key type, key size and signature algorithm, it reports the TLS protocol and cipher negotiated, the Strict-Transport-Security policy, OCSP stapling and embedded Certificate Transparency SCTs, plus derived checks: days until expiry, an expiring-soon flag and self-signed detection. To see which TLS versions a server still accepts, pair it with TLS Checker.

What people use it for

SSL Monitoring and Expiry Alerts

DevOps teams check their domains daily from a cron job or uptime monitor, alerting on certificates close to expiry, failed chain validation or a hostname mismatch before browsers start showing warnings.

Customer Domain Audits

When clients point custom hostnames to a SaaS platform, automated onboarding scripts verify validity status and key strength before activating traffic.

Certificate Chain and Key Audits

Security teams sweep corporate web properties for setups that need fixing: certificates that fail validation, servers missing an intermediate, RSA keys under 2048 bits, SHA-1 signatures or no HSTS policy.

Partner Domain Verification

To prevent broken checkouts, e-commerce marketplaces inspect partner payment gateways to confirm validity windows before routing shopper transactions.

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON

Default REST response

XML

Markup format

YAML

Human-readable

CSV

Tabular export

Beta

GraphQL

Query language

New

MCP

For AI agents

How it compares

Side by side with the tools people weigh SSL Certificate Checker against — what each one is better at, in plain terms.

Request parameters — GET /v1/sslchecker

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

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curl "https://api.apiverve.com/v1/sslchecker?domain=ebay.com" \
  -H "x-api-key: YOUR_API_KEY"

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Response — GET /v1/sslchecker

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

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{
  "status": "ok",
  "error": null,
  "data": {
    "subject": {
      "C": "US",
      "ST": "California",
      "O": "eBay, Inc.",
      "CN": "ebay.com"
    },
    "issuer": {
      "C": "GB",
      "O": "Sectigo Limited",
      "CN": "Sectigo Public Server Authentication CA OV R40"
    },
    "subjectaltname": "DNS:ebay.com, DNS:befr.ebay.be, DNS:benl.ebay.be, DNS:cafr.ebay.ca, DNS:e-bay.com, DNS:e-bay.it, DNS:ebay.at, DNS:ebay.be, DNS:ebay.ca, DNS:ebay.ch, DNS:ebay.co.nz, DNS:ebay.co.uk, DNS:ebay.com.au, DNS:ebay.com.cn, DNS:ebay.com.hk, DNS:ebay.com.my, DNS:ebay.com.ph, DNS:ebay.com.sg, DNS:ebay.de, DNS:ebay.es, DNS:ebay.fr, DNS:ebay.ie, DNS:ebay.in, DNS:ebay.io, DNS:ebay.it, DNS:ebay.nl, DNS:ebay.ph, DNS:ebay.pl, DNS:ebay.us, DNS:ebay.vn, DNS:shorturiweb.ebay.com, DNS:wwww.ebay.co.uk, DNS:wwww.ebay.com, DNS:wwww.ebay.com.au, DNS:wwww.ebay.de, DNS:wwww.ebay.in, DNS:wwww.ebay.it",
    "infoAccess": {
      "CA Issuers - URI": [
        "http://crt.sectigo.com/SectigoPublicServerAuthenticationCAOVR40.crt"
      ],
      "OCSP - URI": [
        "http://ocsp.sectigo.com"
      ]
    },
    "ca": false,
    "bits": 2048,
    "valid_from": "Oct  6 00:00:00 2026 GMT",
    "valid_to": "Apr 22 23:59:59 2027 GMT",
    "serialNumber": "19FD41E42C169CF248511D2BEE660A83",
    "domain": "ebay.com",
    "isExpired": false,
    "isValid": true,
    "daysUntilExpiry": 182,
    "isExpiringSoon": false,
    "isSelfSigned": false,
    "protocol": "TLSv1.3",
    "cipher": "TLS_AES_128_GCM_SHA256",
    "isTrusted": true,
    "trustError": null,
    "hostnameMatches": true,
    "chain": [
      {
        "subject": "ebay.com",
        "issuer": "Sectigo Public Server Authentication CA OV R40",
        "validTo": "Apr 22 23:59:59 2027 GMT",
        "isCA": false
      },
      {
        "subject": "Sectigo Public Server Authentication CA OV R40",
        "issuer": "Sectigo Public Server Authentication Root R46",
        "validTo": "May 13 23:59:59 2040 GMT",
        "isCA": true
      },
      {
        "subject": "Sectigo Public Server Authentication Root R46",
        "issuer": "USERTrust RSA Certification Authority",
        "validTo": "Jan 18 23:59:59 2038 GMT",
        "isCA": true
      },
      {
        "subject": "USERTrust RSA Certification Authority",
        "issuer": "USERTrust RSA Certification Authority",
        "validTo": "Jan 18 23:59:59 2038 GMT",
        "isCA": true
      }
    ],
    "keyType": "RSA",
    "signatureAlgorithm": "sha256WithRSAEncryption",
    "hasEmbeddedSCTs": true,
    "ocspStapled": true,
    "hsts": {
      "present": true,
      "maxAge": 31536000,
      "includeSubDomains": false,
      "preload": false
    }
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 10 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Zero-code embed — one snippet, no backend

Drop an interactive SSL Certificate Checker form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.

Changelog — SSL Certificate Checker API

Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.

Currently v1Data refreshed realtime