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 our breakdown of the top domain security APIs available in 2026.
This guide is published by ComplianceLayer. ComplianceLayer is one of the products compared below.
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–$499/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: Scoped to SSL/TLS, so DNS, headers, and ports are out of scope. Rate-limited to one scan per host per 24 hours on the free API, and results are public 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, low-cost subscription tiers, fast response times.
Cons: Scoped to breach data rather than live infrastructure scanning. Domain search sits on a paid tier.
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: Scoped to exposure data rather than SSL or DNS/email analysis. API credits can deplete quickly at scale, the query syntax has a learning curve for non-technical users, and remediation guidance is not part of the product.
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: Scoped to DNS/WHOIS history rather than SSL analysis, security grading, or remediation — primarily a recon/OSINT tool.
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 | See vendor | |||||
| Shodan | Limited | See vendor | |||||
| SecurityTrails | History only | 50 queries/mo | See vendor |
Common questions
What is the best domain security API for developers?
ComplianceLayer is a 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; it is rate-limited to one scan per host per day and focuses on SSL/TLS. For full-coverage free scanning (SSL + DNS + headers + ports), ComplianceLayer's free tier is a strong option.
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.
All product names, logos, and brands are the property of their respective owners. ComplianceLayer is not affiliated with, sponsored by, or endorsed by any company mentioned on this page. Competitor information is based on publicly available sources as of mid-2026, may be incomplete or outdated, and should be verified with the vendor.