Domainr / Fastly Alternative for Domain Availability Checks

Introduction

Domainr has long been known for fast domain search and availability status. Today, Domainr is part of Fastly, and the product appears as the Fastly Domain Research API. That matters because Fastly is not just an availability API vendor: it is a broad edge cloud platform with CDN, compute, security, observability, domain management, TLS, and many other products.

This article is not a "Fastly is bad" comparison. Fastly does a lot more than WhoisJSON, and the Domain Research API has capabilities WhoisJSON does not try to replicate: instant search, suggestions, premium domain signals, aftermarket status, registry-level detail, and autocomplete-style experiences.

The narrower question is this: if you mainly need to check whether domains are available for registration, which API is more economical? For that specific workload, WhoisJSON is cheaper at common production volumes. For implementation details, see the Domain Availability API product page and the developer guide. For broader provider comparisons, see our best domain availability API guide.

Domainr / Fastly Alternative: Best Choice by Use Case

The right answer depends on the product you are building. A domain registrar search box and a backend availability audit do not need the same API.

What Fastly Domain Research API Does Well

Fastly documents the Domain Research API as a way to retrieve algorithmic domain search results and check domains for detailed availability. The public Domainr page also positions the API around real-time availability, premium-priced names, aftermarket signals, and instant suggestion experiences. In practical terms, Fastly is strongest when availability is part of a product search flow.

Fastly is a strong choice when you need:

• Search and suggestion UX: autocomplete-style domain discovery, extension suggestions, and naming flows.
• Detailed status semantics: values such as inactive, active, reserved, premium, marketed, transferable, expiring, deleting, and unknown.
• Premium and aftermarket context: useful when your product shows whether a domain may be available through a marketplace, not only through new registration.
• Fastly platform fit: useful for teams already using Fastly for edge delivery, compute, TLS, security, or observability.

Where WhoisJSON Is Not a Fastly Replacement

WhoisJSON is not trying to replace Fastly's domain search experience. If your product needs autocomplete, domain suggestions, premium availability semantics, or aftermarket purchase paths, Fastly / Domainr is the stronger fit.

WhoisJSON is designed for a narrower workflow: check whether a domain is available, then enrich that domain with WHOIS/RDAP, DNS, SSL certificate, subdomain, or monitoring data when needed.

Pricing Comparison: Availability Checks

Fastly's public pricing page lists Domain Research API Status-Precise with 10,000 free requests, then $0.001 per request from 10,000 to 1 million requests per month, $0.0008 from 1 million to 5 million, $0.0006 from 5 million to 25 million, and $0.0005 beyond 25 million.

WhoisJSON uses fixed monthly plans. The Basic plan includes 1,000 requests/month. Pro is $10/month for 30,000 requests, Ultra is $30/month for 150,000 requests, and Scale is $50/month for 1,000,000 requests. Those requests can be used across the included API endpoints, not only domain availability.

Calculation note: examples use the public Fastly Status-Precise pricing shown for June 1, 2026 and subtract the 10,000 free monthly requests before applying the $0.001/request tier up to 1 million requests. Always re-check current vendor pricing before making a procurement decision.

API Shape: Detailed Status vs Simple Boolean

The API shape is different because the products optimize for different jobs.

Fastly status responses can express multiple states and tags. That is useful when you need to distinguish a name that is available for new registration from a name that is parked, premium-priced, reserved, marketed, transferable through an aftermarket, or temporarily unknown.

WhoisJSON's domain availability endpoint is deliberately simpler. It answers the question most backend workflows ask first: can this domain currently be registered?

curl "https://whoisjson.com/api/v1/domain-availability?domain=example.com" \
  -H "Authorization: TOKEN=YOUR_API_KEY"

{
  "domain": "example.com",
  "available": true
}

The endpoint is documented in WhoisJSON's API documentation and in the OpenAPI spec as GET /api/v1/domain-availability. Every response also includes a Remaining-Requests header so production systems can track quota. For production retry and quota handling patterns, see the WHOIS API rate limits and retries guide.

Bulk Domain Availability Checks

The price gap becomes more visible when availability checks move from an interactive search box to bulk processing. A naming tool might generate thousands of candidates. A brand protection workflow might check typo variants across many TLDs every day. A portfolio audit might scan owned, expired, and defensive domains on a schedule.

WhoisJSON does not require a special batch endpoint for this. The reliable pattern is controlled client-side batching: send one request per domain to /domain-availability, keep concurrency within your plan's rate limit, retry individual failures, and store each result separately. The same pattern applies when you enrich unavailable domains with WHOIS, DNS, or SSL data.

When to Choose Each API

Choose Fastly / Domainr when:

• You are building an instant domain search UI.
• You need suggestions, alternate TLDs, IDNA/Unicode search behavior, or registrar-oriented discovery.
• You need premium, aftermarket, or detailed domain status semantics.
• You already use Fastly and want domain research inside the same vendor platform.

Choose WhoisJSON when:

• You run recurring domain availability checks in the background.
• You need predictable fixed monthly pricing for 30,000 to 1,000,000 checks.
• You want availability plus WHOIS/RDAP, DNS records, SSL certificate checks, subdomain discovery, and monitoring.
• Your application wants a simple boolean response, not a search/suggestion product.

Example Workflow: Availability Then Enrichment

A common WhoisJSON pattern is to start with availability, then enrich only the domains that need more context. That keeps request usage easy to reason about. The same approach also fits domain portfolio audits; see the domain portfolio management API guide for a complete operations workflow.

Read the domain portfolio management API guide for an example that combines availability, WHOIS, DNS, SSL, and monitoring across many domains.

const API_KEY = process.env.WHOISJSON_API_KEY;
const BASE_URL = 'https://whoisjson.com/api/v1';

async function getJson(path, domain) {
  const url = `${BASE_URL}${path}?domain=${encodeURIComponent(domain)}`;
  const response = await fetch(url, {
    headers: { Authorization: `TOKEN=${API_KEY}` }
  });

  if (!response.ok) {
    throw new Error(`WhoisJSON returned ${response.status}`);
  }

  return response.json();
}

async function inspectCandidate(domain) {
  const availability = await getJson('/domain-availability', domain);

  if (availability.available) {
    return { domain, available: true };
  }

  const [whois, dns, ssl] = await Promise.all([
    getJson('/whois', domain),
    getJson('/nslookup', domain),
    getJson('/ssl-cert-check', domain)
  ]);

  return { domain, available: false, whois, dns, ssl };
}

For naming tools, this can support bulk checks against generated candidates. For security teams, the same pattern helps detect when a watched brand variant becomes registered and then immediately enrich it with WHOIS, DNS, and SSL signals.

Conclusion

Fastly Domain Research API is the better fit for rich domain search, suggestions, premium status, aftermarket signals, and teams already invested in the Fastly platform. It is a broader product, and that breadth is real.

WhoisJSON is the better fit when the job is narrower: check domain availability at predictable monthly volume, then optionally enrich the result with WHOIS, DNS, SSL, subdomains, and monitoring. For that specific availability-check workload, WhoisJSON is significantly cheaper at 30,000, 150,000, and 1,000,000 monthly requests.