Compare›Alacritty vs xterm.js

Alacritty vs xterm.js

Side-by-side terminal feature comparison

Summary

Alacritty

61%

142/233 passed

34 partial

vs

xterm.js

66%

154/233 passed

15 partial

55 features differ between these terminals

Feature Comparison

Character Sets

Feature	Alacritty	xterm.js
DEC line drawing character set	✓	✓
DEC Special Graphics	✓	✓
G0/G1 character set switching	✓	✓
UTF-8 mode	✓	✓

Cursor

Feature	Alacritty	xterm.js
ANSI restore cursor (CSI u)	✓	✓
ANSI save cursor (CSI s)	✓	✓
CPL cursor preceding line (CSI F)	✓	✓
CUD stops at bottom	✓	✓
CUP at screen boundaries	✓	✓
CUP with DECOM	✓	✓
CUU stops at top	✓	✓
Hide cursor (DECTCEM)	✓	~
Cursor horizontal absolute (CHA)	✓	✓
HPA horizontal position absolute (CSI `)	✓	✓
Cursor position (CUP)	✓	✓
Cursor back (CUB)	✓	✓
Cursor down (CUD)	✓	✓
Cursor forward (CUF)	✓	✓
Cursor home	✓	✓
Cursor up (CUU)	✓	✓
Cursor next line (CNL)	✓	✓
Cursor position report (DSR 6)	~	~
Reverse Wrap (Mode 45)	✗	✓
Save/restore cursor (DECSC)	✓	✓
Cursor shape (DECSCUSR)	✓	~
VPA vertical position absolute (CSI d)	✓	✓

Device Status

Feature	Alacritty	xterm.js
Mode Report (DECRPM)	~	✓
Request Setting (DECRQSS)	~	✓
DSR ?996 — color scheme query	?	?
COLORTERM env variable	?	?
KITTY_* env variables	?	?
LC_TERMINAL env variable	?	?
NO_COLOR env variable	?	?
TERM env variable	?	?
TERM_PROGRAM env variable	?	?
VTE_VERSION env variable	?	?
WEZTERM_* env variables	?	?
WT_SESSION env variable	?	?
Primary device attributes (DA1)	~	~
Secondary Device Attributes (DA2)	~	✓
Device status report (DSR 5)	~	~
Feature Reporting (TERM_FEATURES)	?	?
Tertiary Device Attributes (DA3)	~	✗
Query Terminfo (XTGETTCAP)	~	✗
XTGETXRES — query resource value (DCS + Q)	✗	✓
XTREPORTCOLORS — report color capabilities (CSI # R)	✗	✓
Terminal Version (XTVERSION)	~	✗
Report window size in pixels (CSI 14 t)	~	~
Report cell size in pixels (CSI 16 t)	~	~
Report text area size in chars (CSI 18 t)	~	~
Report icon label (CSI 20 t)	✗	~
Report window title (CSI 21 t)	✗	~
Push title/icon stack (CSI 22 ; 0 t)	✓	✓
Pop title/icon stack (CSI 23 ; 0 t)	✗	✓

Editing

Feature	Alacritty	xterm.js
DECCARA — change attrs in rectangle	✗	✗
DECCRA — copy rectangular area	✗	✗
DECDC — delete columns (CSI Ps ' ~)	✗	✗
DECERA — erase rectangular area	✗	✗
DECFRA — fill rectangular area	✗	✗
DECIC — insert columns (CSI Ps ' })	✗	✗
DECRARA — reverse attrs in rectangle	✗	✗
DECRQCRA — checksum rectangular area	✗	✗
DECSACE — select attribute-change extent	✓	✓
DECSERA — selective erase rectangular area	✗	✗
Delete characters (DCH)	✓	✓
Delete lines (DL)	✓	✓
Insert characters (ICH)	✓	✓
Insert lines (IL)	✓	✓
Repeat character (REP)	✓	✓
SL — shift left (CSI Ps SP @)	✗	✗
SR — shift right (CSI Ps SP A)	✗	✗

Erase

Feature	Alacritty	xterm.js
Erase character (ECH)	✓	✓
ED at scroll region boundary	✓	✓
EL erases with bg color	✓	✓
Erase line (EL 2)	✓	✓
Erase to BOL (EL 1)	✓	✓
Erase to EOL (EL 0)	✓	✓
Erase above (ED 1)	✓	✓
Erase screen (ED 2)	✗	✓
Erase below (ED 0)	✓	✓
Erase scrollback (ED 3)	✓	✓
Selective Erase (DECSED)	✗	✓

Extensions

Feature	Alacritty	xterm.js
System clipboard paste	?	?
Font ligatures	?	?
iTerm2 Inline Images (OSC 1337)	✗	✗
Kitty graphics protocol	✗	✗
Kitty graphics: animation	✗	✗
Kitty graphics: display	✗	✗
Kitty graphics: transmit	✗	✗
Kitty graphics: Unicode placeholders	✗	✗
Kitty keyboard protocol	✓	✗
Kitty keyboard: DISAMBIGUATE (flag 1)	✓	✗
Kitty keyboard: REPORT_ALL_KEYS (flag 8)	✓	✗
Kitty keyboard: REPORT_ALTERNATE (flag 4)	✓	✗
Kitty keyboard: REPORT_EVENTS (flag 2)	✓	✗
Kitty keyboard: REPORT_TEXT (flag 16)	✓	✗
Desktop Notifications (OSC 9/777)	~	✗
VS Code Shell Integration (OSC 633)	✗	✗
Icon and title (OSC 0)	✓	✓
Icon name (OSC 1)	✓	✓
Foreground color query (OSC 10)	~	✗
Reset color palette (OSC 104)	✗	✗
Background color query (OSC 11)	~	✗
Reset foreground color (OSC 110)	✗	✗
Reset background color (OSC 111)	✗	✗
Reset cursor color (OSC 112)	✗	✗
Reset pointer fg color (OSC 113)	?	?
Reset pointer bg color (OSC 114)	?	?
Reset highlight background (OSC 117)	✓	✓
Reset highlight foreground (OSC 119)	✓	✓
Cursor color (OSC 12)	✗	✗
OSC 133;A prompt start (FTCS_PROMPT)	✓	✓
OSC 133;B command start (FTCS_COMMAND_START)	✓	✓
OSC 133;C command executed (FTCS_COMMAND_EXECUTED)	✓	✓
OSC 133;D command finished (FTCS_COMMAND_FINISHED)	✓	✓
OSC 133;P properties	✓	✓
iTerm2 Capability Reporting (OSC 1337)	✗	✗
iTerm2 Cell Size Reporting (OSC 1337)	✗	✗
Highlight background (OSC 17)	✗	✗
Set Wayland app-id (OSC 176)	?	?
Highlight foreground (OSC 19)	✗	✗
Window title (OSC 2)	✓	✓
Kitty color protocol (OSC 21)	✗	✗
Pointer shape (OSC 22)	?	?
Kitty color stack push (OSC 30001)	?	?
Systemd context (OSC 3008)	?	?
Kitty color stack pop (OSC 30101)	?	?
Color palette (OSC 4)	✗	✗
Audio sound (OSC 440)	?	?
Special color (OSC 5)	✗	✗
Clipboard access (OSC 52)	~	✗
OSC 52 clipboard read	~	✗
OSC 52 clipboard write	✓	✓
OSC 5522 advanced clipboard	✗	✗
Screen flash (OSC 555)	?	?
OSC 633;A prompt start	✓	✓
OSC 633;B prompt end	✓	✓
OSC 633;C pre-execution	✓	✓
OSC 633;D command finished	✓	✓
OSC 633;E set commandline	✓	✓
OSC 633;P properties	✓	✓
OSC 66 text sizing	✗	✗
VTE termprop (OSC 666)	?	?
Current directory (OSC 7)	~	✗
Locale query/set (OSC 701)	?	?
Version query (OSC 702)	?	?
Set normal font (OSC 710)	?	?
Scroll view up (OSC 720)	?	?
Cell size report (OSC 776)	?	?
Notifications (OSC 777)	?	?
Font size query/set (OSC 7770)	?	?
Font + window size (OSC 7777)	?	?
Hyperlinks (OSC 8)	✓	✓
OSC 9;4 progress bar	?	?
Desktop notifications (OSC 99)	?	?
Text reflow on resize	✓	✓
Semantic prompts (OSC 133)	✗	✗
Sixel graphics	✗	✗
Sixel support in DA1	✗	✗
Sixel geometry report (CSI ? Pi;Pa;Pv S)	✗	✓
24-bit truecolor	✓	✓

Input Protocols

Feature	Alacritty	xterm.js
Button-Event Mouse (1002)	✓	✓
CSI u Key Encoding	✓	✗
Kitty click events	?	?
modifyOtherKeys	~	✗
modifyOtherKeys mode 3	~	✗
Pixel Mouse Reporting (1016)	~	✗
urxvt Mouse Reporting (1015)	✗	✗
X10 Mouse Tracking (9)	✗	✓

Modes

Feature	Alacritty	xterm.js
Enter alt screen (DECSET 1049)	✓	✓
Exit alt screen (DECRST 1049)	✓	✓
Alt-scroll mouse wheel (?1007)	✓	✗
Alt screen clear-on-enter (?1047)	~	✓
Save/restore cursor (?1048)	~	✓
Alt screen legacy (?47)	✗	✓
App cursor keys (DECCKM)	✓	✓
Application keypad (DECKPAM)	✓	✓
Auto-wrap (DECAWM)	✓	✓
Bracketed paste (DECSET 2004)	✓	✓
Mode 2031 color scheme reporting	✗	✗
DECCOLM 80/132 column switch (?3)	✓	✗
DECSCLM — smooth scroll mode	?	?
DECSSCLS — set scroll speed	?	?
Focus tracking (DECSET 1004)	✓	✓
Insert/replace mode (IRM)	✓	✓
Left/Right Margins (DECLRMM, Mode 69)	~	✗
All motion mouse (DECSET 1003)	✓	✓
SGR mouse mode (DECSET 1006)	~	~
Mouse tracking (DECSET 1000)	✓	✓
Origin mode (DECOM)	✓	✓
Reverse video (DECSCNM)	~	~
Synchronized output (DECSET 2026)	✓	✓
UTF-8 mouse mode (?1005)	✓	✗
Pop color palette (CSI # Q)	✗	✓
XTPOPSGR — pop SGR stack (CSI # })	✗	✓
Push color palette (CSI # P)	✗	✓
XTPUSHSGR — push SGR stack (CSI # {)	✗	✓
XTRESTORE — restore DEC private modes (CSI ? Pm r)	✗	✓
XTSAVE — save DEC private modes (CSI ? Pm s)	✗	✓

Reset

Feature	Alacritty	xterm.js
DECALN screen alignment (ESC # 8)	✓	✓
Backend reset() method	✓	✓
Full reset (RIS)	✓	✓
SGR reset clears attributes	✓	✓
Soft reset (DECSTR)	~	✓

Scrollback

Feature	Alacritty	xterm.js
Scrollback accumulates	✓	✓
Alt screen separate scrollback	✓	✓
DECSTBM constrains scrolling	✓	✓
DECSTBM reset to full screen	✓	✓
Reverse index (RI)	✓	✓
Scroll down (SD)	✓	✓
Scroll up (SU)	✓	~
Scroll region (DECSTBM)	✓	✓
Total line count	✓	✓

SGR (Text Styling)

Feature	Alacritty	xterm.js
256-color bg (SGR 48;5)	✓	✓
Bright bg colors (SGR 100-107)	✓	✓
Default bg color (SGR 49)	✓	✓
Standard bg colors (SGR 40-47)	✓	✓
24-bit bg (SGR 48;2)	✓	✓
Blink (SGR 5)	~	~
Bold (SGR 1)	✓	✓
Faint/dim (SGR 2)	✓	✓
256-color fg (SGR 38;5)	✓	✓
Bright fg colors (SGR 90-97)	✓	✓
Default fg color (SGR 39)	✓	✓
Standard fg colors (SGR 30-37)	~	✓
24-bit fg (SGR 38;2)	✓	✓
Hidden/invisible (SGR 8)	~	~
Inverse video (SGR 7)	✓	✓
Italic (SGR 3)	✓	✓
Overline (SGR 53)	✓	✓
Reset all (SGR 0)	✓	✓
Reset bold/dim (SGR 22)	✓	✓
Reset inverse (SGR 27)	✓	✓
Reset italic (SGR 23)	✓	✓
Reset underline (SGR 24)	✓	✓
Strikethrough (SGR 9)	✓	✓
Underline color, indexed (SGR 58;5)	~	✓
Reset underline color (SGR 59)	✓	✓
Underline color, truecolor (SGR 58;2)	~	✓
Underline color (SGR 58)	~	✓
Curly underline (SGR 4:3)	✓	✓
Dashed underline (SGR 4:5)	✓	✓
Dotted underline (SGR 4:4)	✓	✓
Double underline (SGR 21)	~	✓
Underline (SGR 4)	✓	✓

Text

Feature	Alacritty	xterm.js
Backspace (BS)	✓	✓
Basic text rendering	✓	✓
CBT backward tab (CSI Z)	✓	✓
CHT forward tab (CSI I)	✓	✓
Combining characters (0 cols)	✓	✓
Carriage return	✓	✓
HTS set tab stop (ESC H)	✓	✓
Index (IND)	✓	✓
Line feed	✓	✓
Next line (NEL)	✓	✓
Overwrite at cursor	✓	✓
Reverse Index at Scroll Top	✓	✓
Tab stops	✓	✓
TBC clear tab stop (CSI g)	✗	✗
CJK wide chars (2 cols)	✓	✓
Emoji wide chars (2 cols)	✓	✗
Regional indicator flags (2 cols)	✗	✗
Variation selector 16 (emoji presentation)	✗	✗
Emoji ZWJ sequences (2 cols)	✓	✓
Text wraps at width	✓	✓

Unicode

Feature	Alacritty	xterm.js
East Asian Ambiguous Width	✓	✓
Grapheme Cluster Cursor Movement	✓	✓
Tab Stops (HT)	✓	✓
Wide Char at Line Wrap	✓	✓

Only in Alacritty

24 features supported by Alacritty but not xterm.js:

• Tertiary Device Attributes (DA3)Device Status
• Query Terminfo (XTGETTCAP)Device Status
• Terminal Version (XTVERSION)Device Status
• Kitty keyboard protocolExtensions
• Kitty keyboard: DISAMBIGUATE (flag 1)Extensions
• Kitty keyboard: REPORT_ALL_KEYS (flag 8)Extensions
• Kitty keyboard: REPORT_ALTERNATE (flag 4)Extensions
• Kitty keyboard: REPORT_EVENTS (flag 2)Extensions
• Kitty keyboard: REPORT_TEXT (flag 16)Extensions
• Desktop Notifications (OSC 9/777)Extensions
• Foreground color query (OSC 10)Extensions
• Background color query (OSC 11)Extensions
• Clipboard access (OSC 52)Extensions
• OSC 52 clipboard readExtensions
• Current directory (OSC 7)Extensions
• CSI u Key EncodingInput Protocols
• modifyOtherKeysInput Protocols
• modifyOtherKeys mode 3Input Protocols
• Pixel Mouse Reporting (1016)Input Protocols
• Alt-scroll mouse wheel (?1007)Modes
• DECCOLM 80/132 column switch (?3)Modes
• Left/Right Margins (DECLRMM, Mode 69)Modes
• UTF-8 mouse mode (?1005)Modes
• Emoji wide chars (2 cols)Text

Only in xterm.js

17 features supported by xterm.js but not Alacritty:

• Reverse Wrap (Mode 45)Cursor
• XTGETXRES — query resource value (DCS + Q)Device Status
• XTREPORTCOLORS — report color capabilities (CSI # R)Device Status
• Report icon label (CSI 20 t)Device Status
• Report window title (CSI 21 t)Device Status
• Pop title/icon stack (CSI 23 ; 0 t)Device Status
• Erase screen (ED 2)Erase
• Selective Erase (DECSED)Erase
• Sixel geometry report (CSI ? Pi;Pa;Pv S)Extensions
• X10 Mouse Tracking (9)Input Protocols
• Alt screen legacy (?47)Modes
• Pop color palette (CSI # Q)Modes
• XTPOPSGR — pop SGR stack (CSI # })Modes
• Push color palette (CSI # P)Modes
• XTPUSHSGR — push SGR stack (CSI # {)Modes
• XTRESTORE — restore DEC private modes (CSI ? Pm r)Modes
• XTSAVE — save DEC private modes (CSI ? Pm s)Modes

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