Baselines›Unicode

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Unicode Baseline

Unicode correctness — wide chars, combining, emoji

Correct handling of Unicode text: East Asian wide characters (CJK ideographs occupying two terminal columns), emoji with zero-width joiners (family emoji, skin tone modifiers), regional indicator flags, variation selectors (VS16 forcing emoji presentation), combining characters, and grapheme cluster cursor movement. These features determine whether a terminal can correctly display and navigate international text and modern emoji.

8 features in this baseline

Analysis2026-04-06

3 of 12 tested terminals achieve 100% Unicode compliance. Lagging: vt100.js (38%), Kitty (63%), Terminal.app (63%). Most commonly missing: Variation selector 16 (emoji presentation), Emoji ZWJ sequences (2 cols), Grapheme Cluster Cursor Movement.

Compliance Scorecard

Terminal Applications

iTerm2

100%8 / 8

Ghostty

100%8 / 8

VS Code

63%5 / 8

Warp

63%5 / 8

Cursor

63%5 / 8

Terminal.app

63%5 / 8

Headless Backends

vterm

100%8 / 8

xterm.js

63%5 / 8

Kitty

100%8 / 8

Alacritty

75%6 / 8

WezTerm

75%6 / 8

vt100.js

38%3 / 8

Guidance

For Developers

Unicode bugs cause cursor misalignment and broken layouts. If your app displays user-generated text, emoji, or CJK characters, test against the Unicode baseline. Use libraries that implement UAX #11 width calculation.

For Terminal Authors

Unicode correctness is the hardest baseline to achieve. The width of a character depends on Unicode version, grapheme cluster rules, variation selectors, and font metrics — and terminals must agree with each other for TUI layouts to work.

Features

Terminal Applications

Feature	iTerm2	Ghostty	VS Code	Warp	Cursor	Terminal.app
Emoji wide chars (2 cols)	✓	✓	✓	✓	✓	✓
Emoji ZWJ sequences (2 cols)	✓	✓	✗	✗	✗	✗
Regional indicator flags (2 cols)	✓	✓	✓	✓	✓	✓
Variation selector 16 (emoji presentation)	✓	✓	✗	✗	✗	✗
Combining characters (0 cols)	✓	✓	✓	✓	✓	✓
East Asian Ambiguous Width	✓	✓	✓	✓	✓	✓
Grapheme Cluster Cursor Movement	✓	✓	✗	✗	✗	✗
Wide Char at Line Wrap	✓	✓	✓	✓	✓	✓

Headless Backends

Parser correctness tested via Termless. A ✓ means the parser accepts the sequence, not that it renders correctly.

Feature	vterm	xterm.js	Kitty	Alacritty	WezTerm	vt100.js
Emoji wide chars (2 cols)	✓	✗	✓	✓	✓	✗
Emoji ZWJ sequences (2 cols)	✓	✓	✓	✓	✓	✓
Regional indicator flags (2 cols)	✓	✗	✓	✗	✓	✗
Variation selector 16 (emoji presentation)	✓	✗	✓	✗	✗	✗
Combining characters (0 cols)	✓	✓	✓	✓	✓	✗
East Asian Ambiguous Width	✓	✓	✓	✓	✓	✓
Grapheme Cluster Cursor Movement	✓	✓	✓	✓	✓	✓
Wide Char at Line Wrap	✓	✓	✓	✓	✗	✗

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