TLD List Repository

Overview

A simple tool to download and maintain up-to-date Top-Level Domain (TLD) lists from the official IANA registry.

This repository contains scripts and data files for fetching and processing the official list of Top-Level Domains (TLDs) from the Internet Assigned Numbers Authority (IANA). The tool automatically downloads the latest TLD list and provides both original case and lowercase versions.

Files

refresh

Main bash script that downloads and processes TLD data

tlds.txt

Lowercase version of the TLD list (processed)

tlds_original.txt

Original case TLD list (as downloaded from IANA)

tlds_original.txt.bak

Backup of the previous original TLD list

Usage

Refreshing TLD Data

To update the TLD lists with the latest data from IANA:

./refresh

The script will:

1. Download the latest TLD list from https://data.iana.org/TLD/tlds-alpha-by-domain.txt
2. Create a backup of the existing original file
3. Save the new data as tlds_original.txt
4. Generate a lowercase version as tlds.txt

Data Format

Both TLD files contain:

• A header comment with version and last updated timestamp
• One TLD per line
• All officially registered top-level domains

Example content:

# Version 2025091800, Last Updated Thu Sep 18 07:07:01 2025 UTC
AAA
AARP
ABB
ABBOTT
...

The lowercase version (tlds.txt) contains the same data but with all domains converted to lowercase for easier programmatic processing.

Features

• Automatic updates from the official IANA source
• Error handling with proper exit codes and cleanup
• Backup mechanism to preserve previous versions
• Dual format output (original case + lowercase)
• Safe operations with temporary files and proper cleanup

Requirements

• Bash shell
• curl for downloading data
• tr for case conversion
• Standard Unix utilities (mv, rm, mktemp)

Data Source

The TLD data is sourced directly from IANA (Internet Assigned Numbers Authority):

Property	Value
Source URL	https://data.iana.org/TLD/tlds-alpha-by-domain.txt
Authority	Official registry for internet domain names
Update frequency	IANA updates this list as new TLDs are approved

Use Cases

Might be useful for:

• Domain validation in web applications
• Email address validation
• DNS monitoring and analysis
• Research and data analysis projects
• Maintaining local TLD databases

Version Information

Attribute	Value
Data Version	2025091800
Last Updated	Thu Sep 18 07:07:01 2025 UTC
Total TLDs	1440 (excluding header comment)