WhoisJSON API review
A focused domain-intelligence API with a free tier and plans from $10/month.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
WhoisJSON API is a hosted REST API for developers and businesses that need structured domain intelligence. Its endpoints cover WHOIS and RDAP registration lookups, DNS record resolution, SSL/TLS certificate validation, real-time domain availability, subdomain discovery, email-domain intelligence, and domain monitoring with change alerts. The product fits cybersecurity, hosting, fraud-prevention, brand-protection, SaaS, and domain-management workflows, especially when applications need machine-readable responses rather than a graphical lookup interface.
Pricing is organized around a free Basic plan and seven paid tiers. Basic costs $0 per month and includes the WHOIS, DNS, SSL, domain availability, email intelligence, subdomain discovery, and monitoring endpoints with JSON output. Pro is $10 per month and adds all seven API endpoints, while Ultra, Scale, and Mega cost $30, $50, and $80 per month respectively; Mega also lists unlimited requests. Giga, Tera, and Titan cost $120, $200, and $399 per month, and each lists unlimited requests with all seven API endpoints. The published plans show monthly billing, while yearly billing costs the price of 10 months.
Its main strength is breadth within domain intelligence: one API can support registration data, infrastructure records, certificate checks, availability, discovery, monitoring, and email-domain risk scoring. A single authentication token is used across the endpoints, and integrations are listed for PHP, Python, Node.js, Claude, Cursor, and Windsurf. JSON is standard, with XML support on qualifying plans. Choose WhoisJSON API when an application needs several domain-data functions behind an API and a free starting point. It is less suitable for buyers seeking a conventional API client or a standalone interface for manual lookups.
WhoisJSON API pros and cons
- Where it wins
- Combines WHOIS, DNS, SSL, availability, and monitoring endpoints
- Adds subdomain discovery and email-domain signup risk scoring
- Supports JSON output with integrations for PHP, Python, and Node.js
- Where it doesn't
- It is an API service rather than a conventional API client
- XML support is limited to qualifying plans
- Higher-volume access requires moving through multiple paid tiers
WhoisJSON API fact sheet, pricing and score →
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