Equivalent shell command
On Linux or macOS this is sort -u file.txt (or sort -uf for case-insensitive). This tool does the same in the browser — handy on Windows, on a phone, or when the list is sitting in your clipboard rather than a file.
Typical uses
Cleaning email or keyword lists, deduplicating log entries, merging exports from multiple sources, and preparing wordlists where duplicates skew results.