# WhoisJSON

> WhoisJSON is a domain intelligence REST API offering WHOIS lookups, DNS records, SSL certificate validation, domain availability checks, subdomain discovery, and domain monitoring — all under a single API key. It covers 1,500+ TLDs with RDAP support, returns normalized JSON or XML, and is priced 10–30× cheaper than comparable services. Free tier: 1,000 requests/month, no credit card required. Paid plans start at $10/month.

WhoisJSON consolidates six domain intelligence endpoints behind one authentication token and one base URL. There are no per-feature upsells, no separate keys per endpoint, and no credit system — every plan grants full access to the entire API surface. RDAP is used automatically for supported registries, with transparent fallback to legacy WHOIS. All responses share the same normalized schema regardless of TLD or protocol source.

Pricing is straightforward: fixed-quota plans (Basic free → Pro $10 → Ultra $30 → Scale $50/month) and unlimited-throughput plans (Mega $80 → Giga $120 → Tera $200 → Atlas $600/month). Compared to WhoisXML API, WhoisJSON is 10–30× cheaper at equivalent volumes — the free tier alone covers what competitors charge $30/month for. Monthly billing, cancel anytime, 99.9% uptime SLA on all plans.

Key technical details for integration:
- Base URL: `https://whoisjson.com/api/v1/`
- Auth: `Authorization: TOKEN=YOUR_API_KEY` header on every request
- Default output: JSON; append `format=xml` for XML
- Cache TTL: 3 hours; bypass with `_forceRefresh=1` (costs 2× credits)
- Rate limits: 20 req/min (free) → 40/60/100 req/min (Pro/Ultra/Scale) → up to 900 req/min (Atlas)
- Usage tracking: `Remaining-Requests` header on every response

## Endpoints

- [WHOIS API](https://whoisjson.com/whois-api): Full registration data — registrar, creation/expiry dates, nameservers, status codes, registrant (when available). RDAP + legacy WHOIS, 1,500+ TLDs.
- [Bulk WHOIS API](https://whoisjson.com/bulk-whois-api): High-volume domain lookups with rate-limit pacing, normalized JSON, and plans up to 900 req/min. Designed for pipeline integration at scale — processes thousands to millions of domains with consistent schema across all TLDs.
- [DNS Lookup API](https://whoisjson.com/nslookup-api): Resolve any record type (A, AAAA, MX, TXT, CNAME, NS, SOA) for any domain in a single call.
- [SSL Certificate API](https://whoisjson.com/ssl-certificates-api): Validate SSL/TLS certificates — issuer, validity period, encryption standard, chain of trust.
- [Domain Availability API](https://whoisjson.com/domain-availability-api): Real-time registration status checks powered by live WHOIS data.
- [Subdomain Discovery API](https://whoisjson.com/subdomain-api): Fast parallel DNS brute-force across 800+ patterns with wildcard detection; returns A and CNAME records.
- [Domain Monitoring](https://whoisjson.com/domain-monitoring): Track changes to WHOIS records, DNS configurations, SSL certificates, and expiry dates. Email alerts on detection.
- [Email Domain Intelligence API](https://whoisjson.com/email-domain-intelligence-api): Score the domain behind a signup email in one call. Disposable and freemail detection, WHOIS/DNS risk signals, and routing actions for B2B onboarding.
- [MCP Server](https://whoisjson.com/mcp): Native Model Context Protocol integration for AI agents and coding assistants.

## Documentation & Reference

- [Full API Documentation](https://whoisjson.com/documentation): Complete endpoint reference, request parameters, response schemas, error codes, SDK examples (curl, Python, Node.js, PHP).
- [OpenAPI Specification](https://whoisjson.com/openapi.json): Machine-readable OpenAPI 3.0 JSON specification.
- [Pricing](https://whoisjson.com/pricing): All plans with quota, rate limit, and monitoring slot details. USD and EUR available.
- [Free API](https://whoisjson.com/free-domain-api): Details on the permanent free tier — 1,000 req/month, all six endpoints, no time limit.
- [FAQ](https://whoisjson.com/faq): Rate limits, caching behavior, RDAP fallback, monitoring alert types, commercial use policy.
- [API Status](https://whoisjson.com/api-status): Live uptime and incident history.

## Blog — Key Articles

- [WhoisJSON vs WhoisXML API vs Whoxy (2026)](https://whoisjson.com/blog/whoisjson-vs-whoisxml-vs-whoxy): Side-by-side pricing, TLD coverage, RDAP support, and decision matrix.
- [Blog](https://whoisjson.com/blog): Domain intelligence, cybersecurity, DNS, WHOIS, and API integration guides.

## Use Cases

WhoisJSON is used by developers and security teams building: cybersecurity scanners and threat intelligence pipelines, bulk domain processing workflows at scale, domain registrar and reseller platforms, brand protection and typosquatting detection tools, SaaS dashboards requiring domain enrichment, infrastructure monitoring and SSL expiry alerting, and AI agents needing structured domain data via MCP.