Features›Device Status›COLORTERM env variable

COLORTERM env variable

Category: device · Baseline: modern

$COLORTERM

The COLORTERM environment variable indicates that the terminal supports truecolor (24-bit) output beyond what TERM implies. The de facto standard values are truecolor and 24bit; either signals that applications can safely emit SGR 38;2;R;G;B and SGR 48;2;R;G;B sequences. Because TERM values rarely encode truecolor capability accurately and terminfo's RGB capability is unevenly populated, COLORTERM has become the most reliable runtime hint for truecolor support. Most modern terminals — kitty, WezTerm, Ghostty, foot, iTerm2, Alacritty, Windows Terminal — set it automatically.

How this is testedmanual
Manual verification required — no automated probe available.

The same probe runs against headless backends (via Termless) and real terminal apps (via a daemon launched in each terminal). This lets us distinguish parser correctness from rendering correctness.

Supported by 0 of 14 backends (0%)

Terminal Applications

Terminal	Version	Support	Notes
iTerm2	3.6.9	? unknown
Ghostty	1.3.1	? unknown
VS Code		? unknown
Warp		? unknown
Cursor		? unknown
Terminal.app		? unknown

Headless Backends

Parser correctness only — a ✓ means the parser accepts the sequence.

Backend	Version	Support	Notes
Alacritty	0.26.0	? unknown
Kitty	0.40.0	? unknown
vt100.js	0.2.1	? unknown
vterm	0.2.0	? unknown
WezTerm	0.1.0-fork.5	? unknown
xterm.js	5.5.0	? unknown

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