Contour

Contour is a GPU-accelerated terminal emulator written in C++23 for Linux, macOS, FreeBSD, OpenBSD and Windows 10 and later, licensed under Apache-2.0. It aims at power users who care about broad terminal protocol coverage, and it is modal, with vi-like input modes for selection and copy and paste, plus a vi-like scrolloff setting.

Rendering needs OpenGL 3.3, either hardware-accelerated or through a software rasterizer, and the CPU must be x86-64 with AES-NI or ARMv8 with crypto extensions. Text features include font ligatures such as those in Fira Code, bold and italic fonts, emoji (including ZWJ sequences and variation selectors), grapheme clusters and high-DPI support. Graphics include Sixel inline images and ReGIS vector graphics from the VT330/VT340. Contour also implements synchronized rendering (mode 2026), configurable text reflow (mode 2028), OSC 8 hyperlinks, OSC 52 clipboard writes, a VT320 host-programmable status line, and its own buffer capture extension for extracting screen contents.

Configuration is a YAML file, contour.yml, generated in ~/.config/contour on first run and reloaded at runtime. Profiles group a color scheme, login shell and related behavior, and key bindings are customizable. Shell integration scripts, generated from the CLI, exist for zsh, fish and tcsh. Other features include vertical line markers for jumping through history, a read-only mode that blocks accidental input such as Ctrl+C, blurred transparent backgrounds on Windows 10+, KDE and GNOME, and blurrable background images.

Contour has tabs and split panes. Daemon mode moves sessions into a background process so they survive closing the window or a dropped SSH link. contour client attaches to the daemon, starting it if needed, and sessions can be reattached from another machine over an encrypted connection. It speaks tmux's control-mode protocol in both directions: the stock tmux binary can attach to a Contour daemon, and contour client --tmux shows a running tmux server as Contour tabs and splits. The README marks daemon mode as experimental, with flags and wire protocol that may still change.