tldx

Product Introduction

1. Definition: tldx is a high-performance, open-source command-line interface (CLI) tool and Model Context Protocol (MCP) server written in Go, designed for bulk domain name generation and real-time availability checking.
2. Core Value Proposition: tldx exists to solve the slow, rate-limited, and cumbersome process of finding available domain names by providing a blazing-fast, concurrent engine that uses modern RDAP lookups instead of legacy WHOIS parsing, enabling developers, entrepreneurs, and AI agents to brainstorm and verify domains at scale.

Main Features

1. Smart Domain Permutation Engine: tldx generates domain combinations by mixing user-provided keywords with customizable prefixes (e.g., get, my), suffixes (e.g., ly, hub), and top-level domains (TLDs). It supports brace expansion (e.g., {get,use}{app,site}) for shell-native workflows. The engine performs these permutations locally before any network check, ensuring high efficiency.
2. Regex-Based Domain Generation: For advanced use cases, tldx can interpret keywords as regular expressions to algorithmically generate domain lists. For example, [a-z]{3} generates all possible three-letter combinations. This feature includes a safety limit, automatically skipping patterns that would generate over 500,000 combinations to prevent resource exhaustion.
3. Concurrent RDAP Availability Checking: The core of tldx's speed is its concurrent checking system using the Registration Data Access Protocol (RDAP). It makes parallel network requests to appropriate domain registries, bypassing the slower, text-based WHOIS protocol and typical rate limits. Results are streamed to stdout in real-time as they are resolved.
4. Flexible Output Formats & MCP Server: Results can be output in multiple structured formats including plain text, JSON array, streaming JSON, CSV, and grouped views (by keyword or TLD). Crucially, tldx includes an integrated MCP server (tldx mcp), allowing AI agents like Claude or integrated development environments to directly call its domain checking and generation tools as programmable resources.

Problems Solved

1. Pain Point: Eliminates the manual, time-consuming process of checking domain availability one-by-one through web registrars or using slow, rate-limited WHOIS scripts. It specifically addresses the inefficiency of legacy WHOIS parsing.
2. Target Audience: The primary users are software developers, DevOps engineers, startup founders, digital marketers, and branding professionals who need to find available domains for projects, products, or companies. A secondary audience is AI agent developers and prompt engineers who integrate the tldx MCP server into automated workflows.
3. Use Cases: Essential for rapidly brainstorming brandable domain names during product naming sessions, bulk-checking expired domain lists, generating and verifying domain hacks (e.g., io TLDs for tech companies), and providing domain availability as a service within AI-powered coding or business planning assistants.

Unique Advantages

1. Differentiation: Unlike web-based domain search tools that are rate-limited and ad-heavy, tldx is a free, open-source CLI tool with no usage restrictions. Compared to simple WHOIS scripts, it offers concurrent checking, intelligent permutation, regex generation, and multiple machine-readable output formats.
2. Key Innovation: The integration of a full-featured MCP server directly into the tool is a significant innovation. It transforms tldx from a standalone CLI utility into a composable AI agent tool, enabling automated domain research within AI-driven development and planning environments. Its use of RDAP over WHOIS is a modern technical foundation for speed and reliability.

Frequently Asked Questions (FAQ)

1. How does tldx check domain availability so fast? tldx uses concurrent RDAP (Registration Data Access Protocol) queries, a modern replacement for WHOIS. It makes many parallel network requests and streams results, avoiding the sequential delays and parsing overhead of traditional WHOIS lookups.
2. Can I use tldx to find short or premium domain names? Yes, by using the regex feature (e.g., [a-z]{2} for two-letter domains) combined with specific TLDs like io or ai, you can systematically generate and check the availability of short, potentially valuable domain names in bulk.
3. What is the tldx MCP server and how do I use it? The tldx MCP server allows AI agents (like Claude Desktop) to call tldx's functions directly. You configure your AI client to run tldx mcp as an MCP server, granting the AI access to tools for checking domains, generating ideas, and listing TLD presets within your conversation.
4. Is tldx completely free to use for commercial purposes? Yes, tldx is 100% free and open-source software released under the Apache 2.0 license. There are no hidden fees, rate limits, or usage tiers, making it suitable for both personal and commercial domain research projects.