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COLORTERM env variable
$COLORTERMThe
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.
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 | |
| Terminal.app | 2.15 | ? unknown | |
| Kitty | 0.46.2 | ? unknown | |
| VS Code | 1.113.0 | ? unknown | |
| Warp | 0.2026.03.18.08.24.03 | ? unknown | |
| Cursor | 2.6.21 | ? unknown |