Kate

Kate is KDE's programmer-oriented text editor. It keeps many documents open at once, lists them in a side panel, and splits the window into any arrangement of views so two files, or two places in one file, sit next to each other. Sessions remember which documents and which layout you had last time.

The editing component underneath is shared with other KDE applications and brings syntax highlighting for a wide range of languages, code folding, rectangular block selection, multiple cursors, bracket matching and a vi input mode for those who prefer modal keys. Search and replace runs over a selection, a document or an entire directory tree, with regular expressions.

Much of the rest arrives through bundled plugins: a terminal panel backed by Konsole, a project view that takes its file list from Git and other version-control systems, a Language Server Protocol client that supplies completion and go-to-definition once a server is installed for the language, a build plugin and a diff viewer. Kate runs on Linux and other Unix-like systems, and KDE also publishes Windows builds.