# dcs4.com

> dcs4.com (Domain Check Service for 4-letter domains) tracks every 4-character .com name — all 36⁴ = 1,679,616 combinations of a-z and 0-9 — and re-checks availability daily against the Verisign .com registry. Right now 582,876 are unregistered (last scan: 2026-10-14). Registration costs $15 USD for 1 year, WHOIS privacy included.

This file tells AI agents how to search, browse and use dcs4.com. Everything below is read-only and needs no API key or sign-in.

## Quick start

- **MCP server** (recommended): `https://dcs4.com/mcp` — Streamable HTTP transport, stateless, no auth. Add it as a remote MCP server / custom connector.
- **JSON API**: `https://dcs4.com/api/v1/...` — plain GET endpoints, CORS enabled, JSON responses.
- **Website**: every name has a canonical page at `https://dcs4.com/domain/{name}.com` (e.g. https://dcs4.com/domain/quiz.com).

Rate limit: 120 requests per minute per IP across the API and MCP server (HTTP 429 with `Retry-After` when exceeded).

## MCP tools

| Tool | Use it to |
|---|---|
| `search_available_domains` | List names that are available to register now. Args: `query`, `pattern`, `sort`, `previously_registered`, `page`, `limit` |
| `check_domains` | Check up to 50 specific names at once (e.g. a brainstormed shortlist). Args: `names` |
| `get_domain` | Full record for one name: status, brand score, price + buy URL, WHOIS, estimated drop date, WHOIS history. Args: `name` |
| `list_expiring_domains` | Registered names nearing expiry or about to drop, soonest first. Args: `query`, `pattern`, `within_days`, `page`, `limit` |
| `get_market_stats` | Totals, 24h/7d movement and the registration price |

Example client config:

```json
{ "mcpServers": { "dcs4": { "type": "http", "url": "https://dcs4.com/mcp" } } }
```

## JSON API

| Endpoint | Returns |
|---|---|
| `GET /api/v1/domains?query=&pattern=&sort=&previously_registered=&page=&limit=` | Available names |
| `GET /api/v1/domains/{name}` | Full record for one name (`quiz` or `quiz.com`) |
| `GET /api/v1/check?names=quiz,zest,abcd` | Status of up to 50 names |
| `GET /api/v1/expiring?query=&pattern=&within_days=&page=&limit=` | Names nearing expiry/drop, with estimated drop dates |
| `GET /api/v1/stats` | Totals, market movement, price |

Paged responses look like `{ "page": 1, "limit": 25, "total": 1234, "has_more": true, "results": [...] }`. Errors are `{ "error": "..." }` with HTTP 400.

## Parameters

- `query` — name filter. `*` matches any run of characters, `?` exactly one. `qu??` = starts with "qu"; `*ai` = ends with "ai"; `?oo?` = double o in the middle; `???8` = ends in 8. Fewer than 4 characters with no wildcard is a prefix match (`ab` = starts with "ab").
- `pattern` — character shape: `llll` (4 letters, the most valuable), `nlll` (digit + 3 letters), `llln` (3 letters + digit).
- `sort` — `recent` (newest available first, default), `brand` (letters-only and consonant-vowel shapes first, then A–Z), `name` (A–Z), `checked` (most recently re-checked).
- `previously_registered` — `true` for names that were registered before and dropped (aged names).
- `within_days` — expiring window, 0–90 (default 30).
- `page` / `limit` — pagination; `limit` defaults to 25, max 100.

## Fields

- `brand_score` — 0–100 pronounceability heuristic (letters-only and consonant-vowel shapes like CVCV score highest). Labels: 85+ Excellent, 70+ Strong, 55+ Good, 40+ Fair.
- `status` — `available`, `taken` or `unchecked`. Availability is from the last daily registry scan; `last_checked` says when.
- `phase` (taken names) — `active`, `grace`, `redemption`, `pendingDelete`. `estimated_drop` is an estimate: expiry + ~75 days, or ~5 days after pending delete begins. Names drop around 18:00 UTC.
- `buy_url` — where a human completes registration.

## Recommended workflows

- **"Find me a 4-letter .com"** → pure 4-letter (`llll`) .com names are almost all registered. Try `search_available_domains` with `pattern: "llll"` first; if it comes back empty, offer (a) letter + digit names (`pattern: "nlll"` or `"llln"`, narrowed with `query` such as `"???1"` or `"z*"`) and (b) `list_expiring_domains` with `pattern: "llll"` for 4-letter names about to drop. Present names with brand scores and links.
- **"Is X available?" / brainstormed names** → `check_domains` with the whole shortlist, then `get_domain` on the ones the user likes.
- **"What's dropping soon?"** → `list_expiring_domains` (`pattern: "llll"` for letters only); `phase: "pendingDelete"` means it drops within ~5 days.
- **Buying** → give the user the `buy_url`. Checkout needs a signed-in human; agents cannot register on a user's behalf.

## Limits

- Only 4-character .com names are tracked (a-z, 0-9; no hyphens, no other TLDs).
- Lists hide names that became available in the last 24 hours with a brand score of 55+; those are a Pro early-access feature on the website. Exact lookups (`get_domain`, `check_domains`) always work.
- Bulk downloads, brand-score filtering, alerts and drop-catching (sniping) are website features for signed-in users: https://dcs4.com/pricing.

## Browse the site

- [Available domains](https://dcs4.com/): searchable list of every available 4-character .com
- [Expiring domains](https://dcs4.com/expiring): names nearing expiry, in grace, redemption or pending delete
- [Previously registered](https://dcs4.com/previously-registered): available names with registration history
- [Domain search](https://dcs4.com/search?q=quiz): jump to a name's page, or filter by pattern
- [Pricing](https://dcs4.com/pricing): Pro plan and drop-catching prices

## Guides

- [4-letter domain search](https://dcs4.com/4-letter-domain-search): Search 4-letter and 4-character .com domains. Check if a name is available, see WHOIS and expiry for taken names, and find open names with wildcard patterns.
- [Available 4-letter domains](https://dcs4.com/available-4-letter-domains): Are any 4-letter .com domains left? We check all 456,976 letter-only names against the registry and show what's free now, what's about to drop, and the closest alternatives.
- [4-character domains](https://dcs4.com/4-character-domains): Browse every available 4-character .com domain. We track all 1,679,616 letter and number combinations and show which ones you can register today.
- [4-letter domain list](https://dcs4.com/4-letter-domain-list): A list of every unregistered 4-character .com domain, sorted A–Z and refreshed daily. Browse it free online, or download it as a plain text file.
- [Pronounceable domains](https://dcs4.com/pronounceable-domains): Find available pronounceable 4-letter .com domains in consonant-vowel patterns like CVCV (e.g. nuvo.com). Short, sayable names for brands and startups.
- [Startup domain names](https://dcs4.com/short-domains-for-startups): Short, brandable 4-character .com names for startups and side projects. Every name is unregistered and scored for brandability.
- [Domains with numbers](https://dcs4.com/4-letter-domains-with-numbers): Find available short .com domains with two letters and two numbers, like ab12.com, 12ab.com or a1b2.com. Patterns include LLNN, NNLL and LNLN.
- [Expired domains](https://dcs4.com/expired-4-letter-domains): Short .com domains that were registered before and have now expired and dropped. Find aged 4-character names with history you can register today.

## Blog

- [What Is a 4-Letter Domain? LLLL.com Explained](https://dcs4.com/blog/what-is-a-4-letter-domain)
- [How Many 4-Letter .com Domains Exist? The 456,976 Math](https://dcs4.com/blog/how-many-4-letter-com-domains-exist)
- [Why 4-Letter Domains Are Valuable: Scarcity, Branding, and Resale](https://dcs4.com/blog/why-4-letter-domains-are-valuable)
- [CVCV and Pronounceable 4-Letter Domains: The Most Brandable Pattern](https://dcs4.com/blog/cvcv-pronounceable-4-letter-domains)
- [4-Letter Domains as Startup Names: Why Founders Pay a Premium](https://dcs4.com/blog/4-letter-domains-as-startup-names)
- [Chinese Premium Letters: How the Chinese Market Values LLLL.com](https://dcs4.com/blog/chinese-premium-letters-llll)
- [How to Find Available 4-Letter .com Domains in 2026](https://dcs4.com/blog/how-to-find-available-4-letter-domains)
- [Expired 4-Letter Domains: How Drop Catching Works](https://dcs4.com/blog/expired-4-letter-domains-drop-catching)
- [4-Letter Domain Pricing Guide: What LLLL.com Names Sell For](https://dcs4.com/blog/4-letter-domain-pricing-guide)
- [4-Letter vs 4-Character Domains: Letters, Digits, and Hyphens](https://dcs4.com/blog/4-letter-vs-4-character-domains)

## Optional

- [Sitemap](https://dcs4.com/sitemap.xml) and [domain sitemap](https://dcs4.com/sitemap-domains.xml)
- [Terms](https://dcs4.com/terms) · [Privacy](https://dcs4.com/privacy)
- Contact: hello@dcs4.com