Best Domain Security APIs
for Developers (2026)
Security teams, MSPs, and developers increasingly need programmatic access to domain risk data. Whether you're building a client dashboard, automating compliance checks, or integrating security scoring into your CI/CD pipeline — here's an objective breakdown of the top domain security APIs available in 2026.
Top 5 Domain Security APIs Compared
1. ComplianceLayer —
ComplianceLayer is purpose-built for automated domain risk assessment via API. Submit a domain, receive a complete JSON report covering SSL/TLS, DNS email security (SPF, DMARC, DKIM), HTTP security headers, and open port detection. Each category gets an A-F letter grade plus specific remediation steps.
Pros: Full coverage in one API call, remediation steps included, simple REST API, free tier, MSP-friendly pricing ($0–$599/mo), structured JSON response, no SDK required.
Cons: Newer platform (2024), smaller brand recognition than enterprise tools, supply chain risk monitoring not included.
2. Qualys SSL Labs API — Best Free SSL Scanner
The gold standard for SSL/TLS analysis. Qualys SSL Labs grades SSL configuration on a A+/A/B/C/D/F scale, checking certificate validity, cipher suites, protocol versions, and known vulnerabilities (BEAST, POODLE, Heartbleed, etc.).
Pros: Free, highly respected in the industry, extremely detailed SSL analysis, no API key required.
Cons: SSL-only (no DNS, headers, or ports), rate-limited to one scan per host per 24 hours on the free API, scans can take 60–90 seconds, no remediation steps, public results by default.
3. HaveIBeenPwned API — Best for Breach Detection
Troy Hunt's breach database API checks whether email addresses or domains have appeared in known data breaches. Useful for assessing credential exposure risk at the domain level.
Pros: Comprehensive breach database, well-documented API, affordable ($3.50/mo for hobbyist access), fast response times.
Cons: Breach data only — no SSL, DNS, headers, or live scanning. Domain search requires paid tier. Not a replacement for infrastructure scanning.
4. Shodan API — Best for Port & Service Exposure
Shodan continuously crawls the internet and indexes open ports, service banners, and device information. The API lets you query exposed services for any IP or domain, making it useful for attack surface mapping.
Pros: Massive indexed dataset, real-time data, powerful filtering, identifies exposed services and devices beyond web ports.
Cons: No SSL or DNS/email analysis, API credits can deplete quickly at scale ($49+/mo for meaningful access), complex query syntax for non-technical users, no remediation guidance.
5. SecurityTrails API — Best for DNS History & Recon
SecurityTrails provides historical DNS data, subdomain enumeration, and WHOIS history via API. Valuable for threat intelligence, domain reconnaissance, and identifying infrastructure changes over time.
Pros: Unique historical DNS data, extensive subdomain discovery, WHOIS history, free tier available (50 queries/mo).
Cons: No SSL analysis, no security grading, not focused on remediation — primarily a recon/OSINT tool. Paid plans start at $50/mo.
ComplianceLayer API: 60-Second Integration
One POST request returns a complete domain security report. Replace YOUR_API_KEY with your key from the dashboard.
curl -X POST https://compliancelayer.net/v1/scan/ \
-H "X-API-Key: YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"domain": "example.com"}'Example response (abbreviated):
{
"domain": "example.com",
"overall_grade": "B",
"overall_score": 74,
"categories": {
"ssl": {
"grade": "A",
"score": 95,
"checks": {
"certificate_valid": true,
"days_until_expiry": 287,
"tls_1_2_enabled": true,
"tls_1_3_enabled": true,
"weak_ciphers": false
}
},
"dns_email": {
"grade": "C",
"score": 55,
"checks": {
"spf_present": true,
"dmarc_present": false,
"dkim_present": true
},
"remediation": [
{
"check": "dmarc_present",
"severity": "high",
"fix": "Add TXT record: _dmarc.example.com \"v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com\""
}
]
},
"http_headers": { "grade": "B", "score": 72 },
"open_ports": { "grade": "A", "score": 100 }
}
}Domain Security API Comparison
| API | SSL | DNS/Email | Headers | Ports | Remediation | Free Tier | Paid from |
|---|---|---|---|---|---|---|---|
| ComplianceLayer | 10 scans/mo | $99/mo | |||||
| Qualys SSL Labs | Yes (rate-limited) | Free | |||||
| HaveIBeenPwned | Limited | $3.50/mo | |||||
| Shodan | Limited | $49/mo | |||||
| SecurityTrails | History only | 50 queries/mo | $50/mo |
Common questions
What is the best domain security API for developers?
ComplianceLayer is the most comprehensive domain security API for developers and MSPs in 2026. A single POST request returns SSL/TLS grades, DNS email authentication status (SPF, DMARC, DKIM), HTTP security header analysis, and open port findings — all in structured JSON with A-F grades and remediation steps. It requires no complex SDK setup and supports automation via a simple REST API key.
Is there a free domain security API?
Yes. ComplianceLayer offers a free tier with 10 domain scans per month — no credit card required. Qualys SSL Labs also has a free API but is rate-limited to one scan per host per day and only covers SSL/TLS. For full-coverage free scanning (SSL + DNS + headers + ports), ComplianceLayer's free tier is the best option available.
What is a security scoring API?
A security scoring API accepts a domain name and returns a quantified risk assessment of that domain's external security posture. ComplianceLayer returns per-category letter grades (A-F) for SSL/TLS, DNS/email security, HTTP headers, and open ports, plus an overall score. This allows developers and MSPs to programmatically assess and compare the security of any domain without manual inspection.
How do I integrate a domain security API into my RMM or PSA?
ComplianceLayer's REST API accepts a POST request with a domain name and your API key. The JSON response includes grades, individual check results, and remediation steps that can be parsed and inserted directly into PSA tickets, RMM alerts, or custom dashboards. Most integrations can be built in under an hour using standard HTTP libraries in Python, Node.js, PowerShell, or any language that can make HTTP requests.