How do I install the Domain Checker skill?

Run npx skillmds@latest add davidondrej/domain-checker in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Domain Checker safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Domain Checker?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Domain Checker free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Domain Checker?

David Ondrej (@davidondrej) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Domain Checker by davidondrej — Agent Skill

Name: Domain Checker
Author: David Ondrej

Domain Checker

Check domain registration in batches through public registry RDAP APIs, without API keys or login. Use for domain availability checks, checking candidate domains, or keyless domain lookup from a CLI. Screens registration status, not brand conflicts, trademark clearance, or guaranteed purchase availability.

David Ondrej Updated Sep 21, 2026

File contents

Domain checker

Run the bundled Python 3 checker. No packages, credentials or browser needed. Resolve scripts/check_domains.py relative to this SKILL.md, regardless of the current working directory.

python3 <skill-dir>/scripts/check_domains.py example.com example.dev example.ai --json

Pass complete domains, not bare brand names or URLs. For a name across several extensions, expand them into explicit domains. The helper supports domains directly under a TLD, including .com, .dev, .ai and .cloud; multi-label suffixes such as .co.uk are outside its scope.

The script discovers registry endpoints from IANA and runs up to 4 requests concurrently. Use small batches. It sends domain queries to public registries, not registrar shopping carts.

Read the results

JSON output is an array of {domain, status, detail} objects. Without --json, output is a short list and elapsed time.

REGISTERED: matching registration record found.
NOT_FOUND: registry reports no record. Do not call this confirmed available. Reserved names, registration rules and premium pricing may still prevent purchase.
UNAVAILABLE: registry explicitly reports a reservation or registration restriction.
UNKNOWN: unsupported registry, malformed response, timeout or HTTP error. Never convert this to available.
INVALID: malformed name or input outside the helper’s supported scope.

Report results briefly, noting they are a live snapshot. Keep exact domains with their statuses. For UNKNOWN, explain the returned reason; on rate limits, wait before retrying rather than increasing concurrency. Bootstrap failure exits nonzero and means no checks completed.

Read registry error bodies. A 404 can contain an explicit reservation; Verisign may return an empty RDAP 404. The helper handles both. It detects some explicit reservation messages, not every registry’s wording. DNS absence and RDAP redirect-service errors are not evidence of availability.

For final purchase availability or a premium quote, use a registrar check. Domain registration status does not establish whether another company uses the name.

Sources: IANA registry discovery, RDAP HTTP semantics, RDAP.org status and rate-limit distinctions.

---name: domain-checkerdescription: Check domain registration in batches through public registry RDAP APIs, without API keys or login. Use for domain availability checks, checking candidate domains, or keyless domain lookup from a CLI. Screens registration status, not brand conflicts, trademark clearance, or guaranteed purchase availability.---# Domain checkerRun the bundled Python 3 checker. No packages, credentials or browser needed.Resolve `scripts/check_domains.py` relative to this SKILL.md, regardless of the current working directory.```shpython3 <skill-dir>/scripts/check_domains.py example.com example.dev example.ai --json```Pass complete domains, not bare brand names or URLs. For a name across several extensions, expand them into explicit domains. The helper supports domains directly under a TLD, including `.com`, `.dev`, `.ai` and `.cloud`; multi-label suffixes such as `.co.uk` are outside its scope.The script discovers registry endpoints from IANA and runs up to 4 requests concurrently. Use small batches. It sends domain queries to public registries, not registrar shopping carts.## Read the resultsJSON output is an array of `{domain, status, detail}` objects. Without `--json`, output is a short list and elapsed time.- `REGISTERED`: matching registration record found.- `NOT_FOUND`: registry reports no record. **Do not call this confirmed available.** Reserved names, registration rules and premium pricing may still prevent purchase.- `UNAVAILABLE`: registry explicitly reports a reservation or registration restriction.- `UNKNOWN`: unsupported registry, malformed response, timeout or HTTP error. Never convert this to available.- `INVALID`: malformed name or input outside the helper’s supported scope.Report results briefly, noting they are a live snapshot. Keep exact domains with their statuses. For `UNKNOWN`, explain the returned reason; on rate limits, wait before retrying rather than increasing concurrency. Bootstrap failure exits nonzero and means no checks completed.Read registry error bodies. A 404 can contain an explicit reservation; Verisign may return an empty RDAP 404. The helper handles both. It detects some explicit reservation messages, not every registry’s wording. DNS absence and RDAP redirect-service errors are not evidence of availability.For final purchase availability or a premium quote, use a registrar check. Domain registration status does not establish whether another company uses the name.Sources: [IANA registry discovery](https://data.iana.org/rdap/dns.json), [RDAP HTTP semantics](https://www.rfc-editor.org/rfc/rfc7480.html), [RDAP.org status and rate-limit distinctions](https://about.rdap.org/).

Frequently asked questions