ICANN publishes new guidance for evaluating similar top-level domain names

The Internet Corporation for Assigned Names and Numbers (ICANN) has released new String Similarity Evaluation (SSE) Data and String Similarity Evaluation Guidelines to support the work of the independent String Similarity Evaluation Panel responsible for assessing applications for new top-level domains (TLDs).

The new resources will be used during the New Generic Top-Level Domain (gTLD) Program: 2026 Round, in accordance with the procedures set out in the Applicant Guidebook (AGB). Their purpose is to help determine whether proposed top-level domain strings are too similar to existing or newly applied-for domain extensions, potentially causing confusion for internet users.

The String Similarity Evaluation Data contains technical information covering the full set of characters defined in the Root Zone Label Generation Rules, which govern how domain names can be represented across different writing systems. The dataset identifies character pairs that script experts have determined to be visually similar and assigns a similarity level to each pair.

This information will be processed by an automated String Similarity Evaluation tool, which compares newly applied-for domain strings against existing top-level domains and other relevant categories of strings identified in the Applicant Guidebook. The tool generates a prescreening report highlighting potential similarities that require further examination.

The String Similarity Evaluation Guidelines explain how members of the independent evaluation panel should conduct manual assessments of proposed domain names and interpret the automated prescreening reports when making their determinations.

According to ICANN, the combination of automated analysis and expert review is intended to provide a consistent methodology for identifying domain names that could be visually confusing before they are delegated into the global Domain Name System.