SSL Certificate Check API

Monitor certificate expiry, detect TLS versions, and inspect certificate chains for any domain with a single API call. Catch expiring certs before they cause downtime.

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What It Returns

Expiry Date & Days Remaining

The certificate's not_after timestamp and a computed days_until_expiry field so you can set up automated alerts before certificates lapse.

Issuer & Subject

Full issuer details (organization, common name) and the certificate subject. Identify whether a site uses Let's Encrypt, DigiCert, Sectigo, or another CA.

TLS Version

The negotiated TLS protocol version (TLS 1.0, 1.1, 1.2, or 1.3). Flag servers still running deprecated TLS versions that violate PCI DSS or SOC 2 requirements.

Certificate Chain

The full certificate chain from leaf to root CA. Detect missing intermediates, self-signed certificates, and chain configuration errors.

Valid From

The not_before timestamp showing when the certificate was issued. Track renewal frequency and identify recently rotated certificates.

Domain Validation

The certificate's subject alternative names (SANs) and common name. Verify that the certificate actually covers the domain you're checking.

Use Cases

DevOps Certificate Monitoring

Run daily checks across all your domains and get alerted when any certificate is within 30 days of expiry. Prevent outages caused by expired SSL certificates before they happen.

Compliance Audits

Verify TLS versions and certificate configurations across your infrastructure for PCI DSS, SOC 2, and ISO 27001 compliance. Generate machine-readable evidence for auditors.

Vendor Security Assessment

Check third-party vendors' SSL configurations before integration. Identify partners using expired certificates, deprecated TLS versions, or misconfigured certificate chains.

Automated Alerting

Build alerting pipelines that check certificates on a schedule and send Slack, PagerDuty, or email notifications when expiry dates approach or TLS configurations degrade.

How It Works

One GET request returns the complete SSL certificate details as structured JSON.

cURL

curl "https://detectzestack.p.rapidapi.com/v1/certificate/check?url=example.com" \
  -H "X-RapidAPI-Key: YOUR_KEY" \
  -H "X-RapidAPI-Host: detectzestack.p.rapidapi.com"

Example Response

{
  "domain": "example.com",
  "certificate": {
    "subject": "CN=example.com",
    "issuer": "CN=R3, O=Let's Encrypt, C=US",
    "not_before": "2026-03-01T00:00:00Z",
    "not_after": "2026-05-30T23:59:59Z",
    "days_until_expiry": 45,
    "serial_number": "03:a1:b2:c3:d4:e5:f6..."
  },
  "tls_version": "TLS 1.3",
  "chain_length": 3,
  "response_ms": 342
}

Why Use an API vs Manual Checking

Aspect	Manual Checking	DetectZeStack API
Scale	One domain at a time in a browser	Hundreds of domains via script or CI/CD
Automation	Manual browser clicks	Cron jobs, CI pipelines, monitoring tools
Alerting	Calendar reminders (if you remember)	Automated alerts on expiry threshold
TLS version detection	Requires openssl CLI knowledge	Included in every response
CI/CD integration	Not possible	Add as a deployment gate or post-deploy check
Output format	Browser UI / raw openssl text	Structured JSON for any language

Included in All Plans

Certificate checks count against your existing API quota. No separate pricing, no add-ons.

Plan	Requests/month	Price
Basic	100	$0/mo
Pro	1,000	$9/mo
Ultra	10,000	$29/mo
Mega	50,000	$79/mo

Frequently Asked Questions

Can I check SSL certificates programmatically?

Yes. The DetectZeStack SSL Certificate Check API lets you check any domain's SSL certificate with a simple GET request. The API returns the certificate's expiry date, issuer, subject, TLS version, and full certificate chain as structured JSON. No browser or manual inspection needed.

What TLS versions does the API detect?

The API detects TLS 1.0, TLS 1.1, TLS 1.2, and TLS 1.3. Each response includes the negotiated TLS version, so you can identify servers still running deprecated versions that pose security risks and may violate compliance requirements like PCI DSS.

How do I monitor SSL certificate expiry?

Call the certificate check endpoint on a schedule (daily or weekly) and check the days_until_expiry field in the response. Set up alerts when the value drops below your threshold (e.g., 30 days). For a step-by-step guide, read SSL Certificate Check API for DevOps.

Is there a free SSL certificate check API?

Yes. DetectZeStack offers a free tier with 100 API requests per month, which includes the SSL certificate check endpoint. No credit card required. Sign up on RapidAPI to get your free API key in under a minute.

Start checking SSL certificates today

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