Dotter — Domain Availability Checker with MCP Mode

When naming a project, the first thing I do is check if the domain is available. Opening a browser, typing the domain, waiting for WHOIS — too slow. I wanted something I could run from the terminal or ask my agent to check in one second. So I built Dotter.

Dotter is a domain availability checker built in Go. Give it a name, and it tells you which TLDs are free in parallel.

$ dotter myproject
✗ myproject.com is TAKEN

  Alternative TLDs for "myproject":
  TLD         Status
  ─────────── ───────
  .dev        ✓ FREE
  .io         ✓ FREE
  .tech       ✓ FREE
  .app        ✓ FREE
  .ai         ✓ FREE
  .net        ✓ FREE

  → 6 TLDs available! Try: myproject.dev

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Key Features

Fast Parallel Checks

Go goroutines check multiple TLDs simultaneously. Default 10 concurrent queries, configurable:

dotter myproject       # Check .com + curated TLDs
dotter myproject --all # Scan ~70 extended TLDs
dotter myproject --tlds .io,.dev,.tech  # Custom list

Two-Stage Detection

1. DNS check (fast) — resolves NS records. NS exists → domain is taken.
2. WHOIS fallback (accurate) — if DNS is inconclusive, queries WHOIS servers.

This combo is both fast and reliable.

MCP Server Mode

Dotter doubles as an MCP server, making it callable by any agent:

dotter mcp   # Start MCP stdio server

Agent tools exposed:

Tool	Description
check_domain	Check domain availability + suggest alternative TLDs

Configure in Hermes Agent:

# ~/.hermes/config.yaml
mcp_servers:
  dotter:
    command: dotter
    args: ["mcp"]

Then just tell your agent: “check if myproject.dev is available.”

Output Formats

Flag	Format	Use Case
--json	JSON	Pipe to other tools
Default	Pretty table	Human readability
Exit code 0	At least one TLD free	Script conditions
Exit code 1	No TLDs free	Blocking logic

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Tech Stack

Component	Choice	Why
Language	Go	Single binary, goroutines for parallel checks
DNS resolution	net.LookupNS	Standard library, no deps
WHOIS	Raw TCP to WHOIS servers	No external library needed
MCP SDK	Custom stdio protocol	Lightweight, no framework
Concurrency	Goroutines + semaphore	Parallel TLD scanning
Size	~8 MB static binary	Instant download
Tests	Go test suite	Core checking logic tested

Quick Start

go install github.com/fxckcode/dotter@latest

# Check a domain
dotter example.com

# Check with alternatives
dotter myproject --tlds .io,.dev,.tech

# JSON output
dotter myproject --json

Or download a pre-built binary from the releases page.

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The project is MIT licensed and open on GitHub.