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Domain Availability API · v1

The domain availability API built for engineers who care about latency.

One endpoint, 350+ TLDs, sub-2-second responses. No marketing wrapper, no upsell on every call — just the data your stack needs to check, monitor, and reserve names at production scale.

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  • 99.98% uptime · 36 months incident-free
  • 4.2M lookups processed yesterday
One call, one response

What GET /v1/availability actually returns.

You send a name, an optional TLD list, and a Bearer token. We return availability, brandability, registrar hints, and a normalized WHOIS summary — the four fields most stacks actually persist.

Latency is reported in the X-AD-Response-Time-Ms response header on every call, so you can graph it against your own stack without instrumenting us separately.

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response.json 
// Request: GET /v1/availability?name=stripe.consulting&tlds=consulting,io,dev
// Header:  Authorization: Bearer ad_live_••••••••••••3f9c

{
  "query": {
    "name": "stripe",
    "tlds_checked": 3,
    "checked_at": "2024-11-08T14:22:07Z"
  },
  "results": [
    {
      "domain": "stripe.consulting",
      "available": true,
      "brandability": 87,
      "premium_price_usd": null,
      "registrar_hints": ["namecheap", "porkbun"]
    },
    {
      "domain": "stripe.io",
      "available": false,
      "brandability": 94,
      "registered_at": "2010-04-18"
    },
    {
      "domain": "stripe.dev",
      "available": false,
      "registered_at": "2019-11-04"
    }
  ],
  "meta": {
    "response_time_ms": 187,
    "cache_hit": false,
    "rate_limit_remaining": 9983
  }
}
By the numbers

What the production surface actually looks like.

Four numbers that answer the only four questions a platform engineer asks before adding a new dependency.

  • 4.2M
    Lookups processed daily
    Across 38,000+ accounts
  • 99.98%
    Uptime since launch
    36 months incident-free
  • 350+
    TLDs per request
    Including nTLDs & IDNs
  • 1.8s
    Average response
    4× faster than the 7.2s industry avg
Endpoints

Four surfaces your stack integrates with.

Every endpoint ships with idempotent semantics, structured errors, and the same X-AD-* response headers — no special-casing per route.

GET /v1/availability

Availability check

Pass a name and an optional TLD list. Returns availability, brandability (0–100), registrar hints, and premium pricing where applicable. Cached at the edge for 6 minutes against our 2.1M-domain proprietary database.

POST /v1/drops

Drop monitoring webhook

Subscribe a name and we POST a signed payload to your endpoint the moment it transitions from registered to available — sub-second delivery on the 50,000+ daily expiring drops we track. Retries with exponential backoff for 24h.

GET /v1/whois/:domain

WHOIS history

Eighteen years of parsed WHOIS records, free to all users. Returns registrant history, nameserver changes, and registrar transfers in a single normalized JSON shape — no scraping, no CAPTCHA, no scraping-rate ceilings.

GET /v1/brandability

Brandability score

The same 0–100 score our search UI uses: phonetics, memorability, trademark risk heuristics, and SEO headroom combined. Add it as a filter on bulk availability checks to rank a candidate list programmatically.

Pricing

Three tiers. One decision.

Free forever for the first 25 monitored names. Paid tiers unlock higher throughput, webhooks, and SLA-backed uptime.

Tier Monthly requests Drop webhooks Uptime SLA  
Free $0 · forever 10,000 — Best-effort Start free
Builder Most popular $49 / month 500,000 Included 99.9% Get API Key
Scale From $399 / month 5,000,000+ Included + custom filters 99.98% Talk to us

All tiers include the full 350+ TLD coverage, WHOIS history, and the brandability score. Rate limits reset on the 1st of each month UTC. Overage is $0.00009 per request on Builder; Scale is flat-rate with volume commits.

Before you integrate

The four questions that gate a production rollout.

Skim these before opening the dashboard — they're the answers most teams only find after the first incident post.

How does authentication work, and where do I rotate keys?

Bearer-token auth via the Authorization header. You can issue up to 10 keys per account from the dashboard, and rotate any one of them without redeploying clients by swapping the X-AD-Active-Key header. Old keys remain valid for a 24-hour grace window after rotation so background workers can drain.

What rate-limit headers does each response carry?

Every 200 returns X-AD-RateLimit-Limit, X-AD-RateLimit-Remaining, and X-AD-RateLimit-Reset (Unix seconds). 429s include the same three plus a Retry-After in seconds. Standard behavior, no special SDK required.

What's the SLA credit structure when uptime drops below the contract?

Builder: 99.9% — credits are 10% of the monthly fee per 0.1% below target, capped at 100% of the month. Scale: 99.98% — same formula, plus a dedicated incident channel and a 30-minute initial-response target. Credits are applied automatically; no claim form required. Status history is public at status.availabledomain.net.

Can I resell the API or embed it inside a client product?

Internal use and embedding in your own product is permitted on every tier. White-label resale of the raw API output to a third party requires the Scale tier and a reseller addendum. The brandability score is the only field with a separate display-attribution requirement when surfaced to end-users — see the API docs §4.2.

Didn't see your question? The full reference covers webhooks, pagination, error envelopes, and idempotency keys.

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