Apps similar to EmEditor include Visual Studio Code, which is free. Other options are Sublime Text, VSCodium, Vim and Zed Editor. There's no shortage of Text Editors like EmEditor, with more than 100 alternatives for Windows, Linux, Mac, Chrome OS and the web.
csvfab is a free, open-source CSV editor for files too large for a spreadsheet. A 5-million-row file (770 MB) opens in under 3 seconds and sorts in about 2, where Excel and LibreOffice Calc stop at 1,048,576 rows.
Janus is a simple, native Linux text editor. Supports UTF-8 and binary data through it's binary editing mode. Spiritual successor to Leafpad.
