What is a DNS Lookup API?
A DNS lookup API lets you query Domain Name System records including A, AAAA, MX, TXT, NS, SOA, and CNAME records. These APIs are essential for email validation, security analysis, and network diagnostics.
Why DomScan is #1
- Generous free tier: 10,000 credits/month with no credit card
- Broad TLD coverage: 1,100+ extensions supported
- Modern REST API with JSON responses and excellent docs
- Remote MCP integration for AI assistants
- All-in-one: availability, valuation, DNS, brand monitoring
Best DNS Lookup APIs - Top 10
DomScan
Our Pick Free Tier- Generous free tier: 10,000 credits/month with no credit card
- Broad TLD coverage: 1,100+ extensions supported
- Modern REST API with JSON responses and excellent docs
SecurityTrails
Runner Up- Massive passive DNS database
- Excellent subdomain enumeration
- Historical WHOIS and DNS data
Netlas
Free Tier- Very broad internet-scan, DNS, SSL, and WHOIS coverage
- Structured datasets are strong for security research
- Useful alternative to scan-first tools like Shodan or Censys
WhoisXML API
Free Tier- Very broad domain and infrastructure coverage
- Historical WHOIS, DNS, and threat data
- Enterprise packages for security workflows
MxToolBox
Free Tier- Best-in-class email diagnostics
- Blacklist monitoring
- SPF/DKIM/DMARC validation
Robtex
Free Tier- Strong passive DNS and reverse passive DNS workflows
- Domain reputation and shared infrastructure views are useful
- Longstanding operator with practical internet tooling
DNSimple
Free Tier- Full registrar with API
- Excellent documentation
- SSL certificate automation
Cloudflare Registrar
- Zero markup on domains
- Beta API can check up to 20 domains at once
- Free DNSSEC, CDN, and SSL
DNSlytics
Free Tier- Generous 2,500-request daily free tier
- Tracking code discovery
- Comprehensive reverse lookups
ViewDNS
Free Tier- Free web-based tools
- Wide range of reverse lookup tools
- Fast to evaluate from the browser
Detailed Reviews
DomScan Review
DomScan is a developer-focused domain intelligence API built around real-time RDAP, broad TLD coverage, and agent integration through MCP.
Pros
- Broad 1,100+ TLD support
- Generous free tier (10K credits/month)
- Clean REST API with JSON responses
- Remote MCP server for AI assistants
Cons
- Newer service (less track record than older providers)
- No historical WHOIS data yet
Our Verdict
DomScan is our top pick for developers building domain-related applications in 2026. The combination of wide TLD coverage, generous free tier, and modern API design makes it the clear choice for most use cases.
SecurityTrails Review
SecurityTrails provides comprehensive DNS intelligence, passive DNS data, subdomain enumeration, and WHOIS history for security researchers and threat intelligence teams.
Pros
- Massive passive DNS database
- Excellent subdomain enumeration
- Historical WHOIS and DNS data
Cons
- Enterprise pricing not transparent
- Limited free tier
- Security-focused, not for domain registration
Our Verdict
SecurityTrails provides comprehensive DNS intelligence, passive DNS data, subdomain enumeration, and WHOIS history for security researchers and threat intelligence teams.
Netlas Review
Netlas combines search, internet-wide scan data, DNS records, SSL certificates, IP WHOIS, and domain WHOIS through structured APIs and bulk datasets.
Pros
- Very broad internet-scan, DNS, SSL, and WHOIS coverage
- Structured datasets are strong for security research
- Useful alternative to scan-first tools like Shodan or Censys
Cons
- Not built around valuation or registrar actions
- Coverage breadth can be overkill for simple product use cases
- Self-serve developer messaging is less streamlined than lightweight APIs
Our Verdict
Netlas combines search, internet-wide scan data, DNS records, SSL certificates, IP WHOIS, and domain WHOIS through structured APIs and bulk datasets.
WhoisXML API Review
WhoisXML API is the go-to solution for enterprise security teams and researchers needing comprehensive threat intelligence and historical domain data. It is powerful but complex.
Pros
- Comprehensive threat intelligence
- Historical WHOIS data access
- Strong security research focus
- Extensive API coverage for security use cases
Cons
- Complex pricing structure
- Overkill for simple availability checks
- Steeper learning curve
Our Verdict
WhoisXML API excels at enterprise security use cases. If you need historical WHOIS data or threat intelligence, it is excellent. For simpler availability checking, it is unnecessarily complex and expensive.
MxToolBox Review
MxToolBox specializes in email deliverability tools including MX lookups, blacklist monitoring, SPF/DKIM/DMARC validation, and DNS diagnostics.
Pros
- Best-in-class email diagnostics
- Blacklist monitoring
- SPF/DKIM/DMARC validation
Cons
- Email-focused, not general domain
- No WHOIS lookup
- Higher pricing for API access
Our Verdict
MxToolBox specializes in email deliverability tools including MX lookups, blacklist monitoring, SPF/DKIM/DMARC validation, and DNS diagnostics.
Robtex Review
Robtex is an established passive DNS and infrastructure intelligence tool focused on DNS history, reverse lookups, and domain reputation signals.
Pros
- Strong passive DNS and reverse passive DNS workflows
- Domain reputation and shared infrastructure views are useful
- Longstanding operator with practical internet tooling
Cons
- Less polished for product-led buyer journeys
- Not focused on valuation or registrar workflows
- Broader threat and monitoring stack is lighter than newer platforms
Our Verdict
Robtex is an established passive DNS and infrastructure intelligence tool focused on DNS history, reverse lookups, and domain reputation signals.
DNSimple Review
DNSimple is a premium domain registrar with a beautifully designed API. If you need domain management alongside availability checking, it is an excellent choice - but it is pricier than API-only alternatives.
Pros
- Excellent API design and documentation
- Full registrar capabilities
- SSL certificate automation
- Great developer experience and support
Cons
- Requires subscription ($29+/mo)
- Fewer TLDs than dedicated APIs
- No free tier for API access
Our Verdict
DNSimple is ideal if you need both domain registration and API access in one package. The excellent documentation and API design justify the premium, but it is overkill for availability-only needs.
Cloudflare Registrar Review
At-cost registration with a beta API for supported domains
Pros
- Zero markup on domains
- Beta API can check up to 20 domains at once
- Free DNSSEC, CDN, and SSL
- Cloudflare users, cost-conscious developers, supported-TLD registration automation
Cons
- Registrar API is still in beta
- Requires Cloudflare account, token, and registrant setup
- No renewal, transfer, or contact-update endpoints in the beta
Our Verdict
Cloudflare Registrar combines registry-price domains with a beta API for search, authoritative availability checks, and standard registration on supported extensions. Checks can show premium pricing, but the beta does not currently support premium registration. The beta also does not yet automate renewals or transfers, and registered domains must use Cloudflare's authoritative DNS.
Sources
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DNSlytics Review
DNSlytics emphasizes reverse lookups, tracking-code pivots, and DNS research, with a newer API v2 beta focused on datasets.
Pros
- Generous 2,500-request daily free tier
- Tracking code discovery
- Comprehensive reverse lookups
Cons
- API v2 coverage is still narrow in beta
- No domain availability API
- WHOIS data is not its core strength
Our Verdict
DNSlytics emphasizes reverse lookups, tracking-code pivots, and DNS research, with a newer API v2 beta focused on datasets.
ViewDNS Review
ViewDNS.info offers a broad toolbox of DNS, reverse IP, reverse MX, WHOIS, and IP history lookups for investigators and operators.
Pros
- Free web-based tools
- Wide range of reverse lookup tools
- Fast to evaluate from the browser
Cons
- Basic API compared to competitors
- No domain availability checking
- API is lighter than dedicated intelligence platforms
Our Verdict
ViewDNS.info offers a broad toolbox of DNS, reverse IP, reverse MX, WHOIS, and IP history lookups for investigators and operators.
How We Rank
Our rankings combine hands-on product testing with public pricing pages, official API documentation, TLD or dataset coverage, documentation quality, and overall developer experience.
Last updated: August 2026