What is a WHOIS API?
A WHOIS API provides programmatic access to domain registration data including registrant information, nameservers, creation/expiration dates, and registrar details. Modern APIs use RDAP (Registration Data Access Protocol) for better structured data.
Why DomScan is #1
- Generous free tier: 10,000 credits/month with no credit card
- Widest TLD coverage: 1,500+ extensions supported
- Modern REST API with JSON responses and excellent docs
- Unique MCP integration for AI assistants like Claude
- All-in-one: availability, valuation, DNS, brand monitoring
Best WHOIS & RDAP APIs - Top 12
DomScan
Our Pick Free Tier- Generous free tier: 10,000 credits/month with no credit card
- Widest TLD coverage: 1,500+ extensions supported
- Modern REST API with JSON responses and excellent docs
WhoisXML API
Runner Up Free Tier- Very broad domain and infrastructure coverage
- Historical WHOIS, DNS, and threat data
- Enterprise packages for security workflows
Whoxy
- Strong historical WHOIS and reverse WHOIS coverage
- Pay-as-you-go entry point for batch research
- Good fit for WHOIS-heavy investigations and reseller tools
SecurityTrails
Free Tier- Massive passive DNS database
- Excellent subdomain enumeration
- Historical WHOIS and DNS data
WHOISJSON
Free Tier- Covers WHOIS, DNS, SSL, and availability in one API
- Simple entry pricing and low-friction onboarding
- Useful free tier for early testing and prototypes
WhoAPI
Free Tier- Established since 2011
- Comprehensive WHOIS parsing
- Good for bulk availability checks
DomainTools
- Decades of historical WHOIS data
- Advanced threat intelligence
- Iris, DNSDB, and monitoring products
WhoisFreaks
Free Tier- Historical WHOIS data
- Reverse WHOIS lookups
- Good free tier (100/day)
RDAP API
Free Tier- Focused RDAP experience for domains, IPs, and ASNs
- Cleaner fit for modern registration-data workflows
- Good option for teams that do not need a huge platform
ViewDNS
Free Tier- Free web-based tools
- Wide range of reverse lookup tools
- Fast to evaluate from the browser
JsonWhois
Free Tier- Simple, focused API
- Budget-friendly pricing
- Clean JSON responses
IP2WHOIS
Free Tier- Straightforward WHOIS lookup coverage
- Part of IP2Location ecosystem
- Useful alongside IP2Location data
Detailed Reviews
DomScan Review
DomScan is the most developer-friendly domain intelligence API available today. Built on modern standards with a focus on real-time RDAP data, it offers unmatched TLD coverage and innovative AI integration.
Pros
- Industry-leading 1,500+ TLD support
- Generous free tier (10K credits/month)
- Clean REST API with JSON responses
- Unique 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.
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.
Whoxy Review
Whoxy focuses on live WHOIS, historical WHOIS, reverse WHOIS, and batch lookup workflows for researchers, resellers, and brand-protection teams.
Pros
- Strong historical WHOIS and reverse WHOIS coverage
- Pay-as-you-go entry point for batch research
- Good fit for WHOIS-heavy investigations and reseller tools
Cons
- No domain valuation workflow
- Limited AI or modern workflow integrations
- Narrower feature set outside WHOIS and DNS research
Our Verdict
Whoxy focuses on live WHOIS, historical WHOIS, reverse WHOIS, and batch lookup workflows for researchers, resellers, and brand-protection teams.
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.
WHOISJSON Review
WHOISJSON packages WHOIS, DNS, SSL certificate, and availability lookups into a lightweight API for teams that need practical lookup coverage without enterprise overhead.
Pros
- Covers WHOIS, DNS, SSL, and availability in one API
- Simple entry pricing and low-friction onboarding
- Useful free tier for early testing and prototypes
Cons
- Less historical depth than larger intelligence platforms
- Smaller ecosystem and fewer enterprise references
- Limited threat-intel and monitoring depth
Our Verdict
WHOISJSON packages WHOIS, DNS, SSL certificate, and availability lookups into a lightweight API for teams that need practical lookup coverage without enterprise overhead.
WhoAPI Review
WhoAPI has been a reliable domain data provider since 2011, offering solid availability checking and WHOIS lookups. While it lacks some modern features, its proven reliability makes it a safe enterprise choice.
Pros
- 13+ years of operational history
- Reliable uptime and performance
- Good bulk checking capabilities
- Established enterprise reputation
Cons
- Higher pricing than alternatives
- Free trial limited to 30 days
- No AI/MCP integration
Our Verdict
WhoAPI is a solid choice for enterprises that prioritize proven reliability over cutting-edge features. The higher price point is justified for mission-critical applications where uptime is paramount.
DomainTools Review
Enterprise-grade domain intelligence and threat detection platform
Pros
- Decades of historical WHOIS data
- Advanced threat intelligence
- Iris, DNSDB, and monitoring products
- Enterprise security teams, SOC analysts, threat hunters, forensic investigators, brand protection at scale
Cons
- Enterprise-only pricing
- Overkill for simple availability checks
- Limited fit for developer-first or low-volume projects
Our Verdict
DomainTools is the undisputed leader in enterprise threat intelligence and historical domain data. If you need decades of WHOIS history or advanced threat analysis for a security operations center, it is unmatched. However, for developers building domain tools or startups, the pricing is prohibitive and the feature set is excessive.
WhoisFreaks Review
Comprehensive WHOIS and DNS intelligence with historical data
Pros
- Historical WHOIS data
- Reverse WHOIS lookups
- Good free tier (100/day)
- Cybersecurity analysts, brand protection teams, domain researchers, forensic investigators
Cons
- No domain availability API
- No AI/MCP integration
- Credit-based pricing complexity
Our Verdict
WhoisFreaks offers excellent value for historical WHOIS research and reverse lookups. The breadth of data (422M+ domains, 555M+ records) and coverage since 1986 makes it a strong choice for cybersecurity and brand protection. The credit-based pricing is fair, though the limited free tier makes evaluation challenging.
RDAP API Review
RDAP API centers on RDAP lookups for domains, IP ranges, and ASNs for teams that want structured registration data without buying a larger intelligence platform.
Pros
- Focused RDAP experience for domains, IPs, and ASNs
- Cleaner fit for modern registration-data workflows
- Good option for teams that do not need a huge platform
Cons
- No valuation, threat monitoring, or naming workflow
- Limited DNS and enrichment depth compared with broader platforms
- Smaller market footprint than established incumbents
Our Verdict
RDAP API centers on RDAP lookups for domains, IP ranges, and ASNs for teams that want structured registration data without buying a larger intelligence platform.
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.
JsonWhois Review
WHOIS API with social data and screenshot capture
Pros
- Simple, focused API
- Budget-friendly pricing
- Clean JSON responses
- Budget-conscious developers, projects needing WHOIS + screenshots, social media monitoring
Cons
- Limited to WHOIS only
- No DNS or availability features
- No bulk operations
Our Verdict
JsonWhois is a decent budget option for developers who need simple WHOIS lookups combined with screenshot capture and social data. The unique combination of features is appealing, but the lack of transparency around TLD coverage and the limited documentation may be concerns for production use.
IP2WHOIS Review
WHOIS lookup API integrated with IP2Location ecosystem
Pros
- Straightforward WHOIS lookup coverage
- Part of IP2Location ecosystem
- Useful alongside IP2Location data
- Developers needing simple WHOIS lookups, IP2Location ecosystem users, fraud prevention teams
Cons
- No DNS lookup features
- Limited bulk and historical workflows
- Limited to WHOIS data
Our Verdict
IP2WHOIS offers a solid WHOIS lookup API with excellent TLD coverage and a reasonable free tier. The integration with IP2Location products is valuable for teams already in that ecosystem. For simple WHOIS lookups, it delivers, but the lack of historical data and bulk operations limits its appeal for advanced use cases.
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: July 2026