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Alacritty
App Terminal + Parser Backend
alacritty_terminal Rust crate via napi-rs.
Alacritty was the first terminal emulator to use GPU-accelerated rendering, announced by Joe Wilm in January 2017. Written in Rust, it proved that GPU rendering could dramatically improve terminal performance — achieving smooth scrolling and low latency that traditional CPU-rendered terminals couldn't match.
Alacritty is deliberately minimal: no tabs, no splits, no built-in multiplexer. It's designed to do one thing well — render text fast — and delegates everything else to tools like tmux. Configuration is via a YAML file. This minimalism is polarizing: some developers love the simplicity, others want integrated features.
The alacritty_terminal Rust crate (the parser/emulator core) is reusable outside Alacritty itself. Termless uses it as a headless backend via napi-rs bindings, testing parser correctness without any rendering.
Backend: alacritty_terminal Rust crate via napi-rs. (native) · v0.26.0
71%
107 passed · 26 partial · 18 failed of 151 features
Tested: March 26, 2026
Analysis2026-03-26
Alacritty scores 88% (133/151) on the terminfo.dev feature matrix, with gaps in the Core TUI, Modern TUI, Rich TUI, Unicode baselines. Ranks #11 of 13 tested terminals. Uniquely missing (all other terminals pass): Reverse Wrap (Mode 45), Erase screen (ED 2). Missing 18 features.
Character Sets
| Feature | Support | Notes |
|---|---|---|
| DEC line drawing character set | ✓ yes | |
| DEC Special Graphics | ✓ yes | |
| G0/G1 character set switching | ✓ yes | |
| UTF-8 mode | ✓ yes |
Cursor
| Feature | Support | Notes |
|---|---|---|
| CUD stops at bottom | ✓ yes | |
| CUP at screen boundaries | ✓ yes | |
| CUP with DECOM | ✓ yes | |
| CUU stops at top | ✓ yes | |
| Hide cursor (DECTCEM) | ✓ yes | |
| Cursor horizontal absolute (CHA) | ✓ yes | |
| Cursor position (CUP) | ✓ yes | |
| Cursor back (CUB) | ✓ yes | |
| Cursor down (CUD) | ✓ yes | |
| Cursor forward (CUF) | ✓ yes | |
| Cursor home | ✓ yes | |
| Cursor up (CUU) | ✓ yes | |
| Cursor next line (CNL) | ✓ yes | |
| Cursor position report (DSR 6) | ~ partial | Headless mode has no output stream for DSR responses |
| Reverse Wrap (Mode 45) | ✗ no | Reverse wrap not supported in alacritty headless mode |
| Save/restore cursor (DECSC) | ✓ yes | |
| Cursor shape (DECSCUSR) | ✓ yes |
Device Status
| Feature | Support | Notes |
|---|---|---|
| Mode Report (DECRPM) | ~ partial | Headless mode has no output stream for DECRPM responses |
| Request Setting (DECRQSS) | ~ partial | Headless mode has no output stream for DECRQSS responses |
| Primary device attributes (DA1) | ~ partial | Headless mode has no output stream for DA1 responses |
| Secondary Device Attributes (DA2) | ~ partial | Headless mode has no output stream for DA2 responses |
| Device status report (DSR 5) | ~ partial | Headless mode has no output stream for DSR responses |
| Feature Reporting (TERM_FEATURES) | ? unknown | |
| Tertiary Device Attributes (DA3) | ~ partial | Headless mode has no output stream for DA3 responses |
| Query Terminfo (XTGETTCAP) | ~ partial | Headless mode has no output stream for XTGETTCAP responses |
| Terminal Version (XTVERSION) | ~ partial | Headless mode has no output stream for XTVERSION responses |
Editing
| Feature | Support | Notes |
|---|---|---|
| Delete characters (DCH) | ✓ yes | |
| Delete lines (DL) | ✓ yes | |
| Insert characters (ICH) | ✓ yes | |
| Insert lines (IL) | ✓ yes | |
| Repeat character (REP) | ✓ yes |
Erase
| Feature | Support | Notes |
|---|---|---|
| Erase character (ECH) | ✓ yes | |
| ED at scroll region boundary | ✓ yes | |
| EL erases with bg color | ✓ yes | |
| Erase line (EL 2) | ✓ yes | |
| Erase to BOL (EL 1) | ✓ yes | |
| Erase to EOL (EL 0) | ✓ yes | |
| Erase above (ED 1) | ✓ yes | |
| Erase screen (ED 2) | ✗ no | Alacritty's ED 2 doesn't clear scrollback content from buffer |
| Erase below (ED 0) | ✓ yes | |
| Erase scrollback (ED 3) | ✓ yes | |
| Selective Erase (DECSED) | ✗ no | DECSED (selective erase) not supported in alacritty |
Extensions
| Feature | Support | Notes |
|---|---|---|
| iTerm2 Inline Images (OSC 1337) | ✗ no | iTerm2 inline images not supported by alacritty |
| Kitty graphics protocol | ✗ no | Not implemented in alacritty |
| Kitty keyboard protocol | ✓ yes | |
| Desktop Notifications (OSC 9/777) | ~ partial | OSC 9 notifications not exposed via alacritty_terminal API |
| VS Code Shell Integration (OSC 633) | ✗ no | VS Code shell integration (OSC 633) not supported |
| Icon and title (OSC 0) | ✓ yes | |
| Foreground color query (OSC 10) | ~ partial | OSC 10 color query not exposed in headless mode |
| Background color query (OSC 11) | ~ partial | OSC 11 color query not exposed in headless mode |
| iTerm2 Capability Reporting (OSC 1337) | ✗ no | iTerm2-specific protocol not supported |
| iTerm2 Cell Size Reporting (OSC 1337) | ✗ no | iTerm2-specific protocol not supported |
| Window title (OSC 2) | ✓ yes | |
| Clipboard access (OSC 52) | ~ partial | OSC 52 clipboard not exposed in headless mode |
| OSC 5522 advanced clipboard | ✗ no | OSC 5522 not implemented in alacritty |
| OSC 66 text sizing | ✗ no | OSC 66 text sizing not implemented in alacritty |
| Current directory (OSC 7) | ~ partial | OSC 7 CWD reporting not exposed via alacritty_terminal API |
| Hyperlinks (OSC 8) | ✓ yes | |
| OSC 9;4 progress bar | ? unknown | |
| Text reflow on resize | ✓ yes | |
| Semantic prompts (OSC 133) | ✗ no | Not implemented in alacritty |
| Sixel graphics | ✗ no | Not implemented in alacritty |
| Sixel support in DA1 | ✗ no | Sixel not implemented in alacritty |
| 24-bit truecolor | ✓ yes |
Input Protocols
| Feature | Support | Notes |
|---|---|---|
| Button-Event Mouse (1002) | ✓ yes | |
| CSI u Key Encoding | ✓ yes | |
| modifyOtherKeys | ~ partial | modifyOtherKeys not exposed via alacritty_terminal API |
| modifyOtherKeys mode 3 | ~ partial | modifyOtherKeys mode 3 not exposed in headless mode |
| Pixel Mouse Reporting (1016) | ~ partial | SGR pixel mouse mode not exposed via alacritty_terminal API |
| urxvt Mouse Reporting (1015) | ✗ no | urxvt mouse mode (?1015) not implemented |
| X10 Mouse Tracking (9) | ✗ no | X10 mouse mode (?9) not implemented |
Modes
| Feature | Support | Notes |
|---|---|---|
| Enter alt screen (DECSET 1049) | ✓ yes | |
| Exit alt screen (DECRST 1049) | ✓ yes | |
| App cursor keys (DECCKM) | ✓ yes | |
| Application keypad (DECKPAM) | ✓ yes | |
| Auto-wrap (DECAWM) | ✓ yes | |
| Bracketed paste (DECSET 2004) | ✓ yes | |
| Mode 2031 color scheme reporting | ✗ no | Mode 2031 not implemented in alacritty |
| Focus tracking (DECSET 1004) | ✓ yes | |
| Insert/replace mode (IRM) | ✓ yes | |
| Left/Right Margins (DECLRMM, Mode 69) | ~ partial | DECLRMM not exposed via alacritty_terminal API |
| All motion mouse (DECSET 1003) | ✓ yes | |
| SGR mouse mode (DECSET 1006) | ~ partial | SGR mouse encoding not exposed via alacritty_terminal API |
| Mouse tracking (DECSET 1000) | ✓ yes | |
| Origin mode (DECOM) | ✓ yes | |
| Reverse video (DECSCNM) | ~ partial | Not exposed via alacritty_terminal API |
| Synchronized output (DECSET 2026) | ✓ yes |
Reset
| Feature | Support | Notes |
|---|---|---|
| Backend reset() method | ✓ yes | |
| Full reset (RIS) | ✓ yes | |
| SGR reset clears attributes | ✓ yes | |
| Soft reset (DECSTR) | ~ partial | DECSTR resets modes but headless probe reads stale state |
Scrollback
| Feature | Support | Notes |
|---|---|---|
| Scrollback accumulates | ✓ yes | |
| Alt screen separate scrollback | ✓ yes | |
| DECSTBM constrains scrolling | ✓ yes | |
| DECSTBM reset to full screen | ✓ yes | |
| Reverse index (RI) | ✓ yes | |
| Scroll down (SD) | ✓ yes | |
| Scroll up (SU) | ✓ yes | |
| Scroll region (DECSTBM) | ✓ yes | |
| Total line count | ✓ yes |
SGR (Text Styling)
Text
| Feature | Support | Notes |
|---|---|---|
| Backspace (BS) | ✓ yes | |
| Basic text rendering | ✓ yes | |
| Combining characters (0 cols) | ✓ yes | |
| Carriage return | ✓ yes | |
| Index (IND) | ✓ yes | |
| Line feed | ✓ yes | |
| Next line (NEL) | ✓ yes | |
| Overwrite at cursor | ✓ yes | |
| Reverse Index at Scroll Top | ✓ yes | |
| Tab stops | ✓ yes | |
| CJK wide chars (2 cols) | ✓ yes | |
| Emoji wide chars (2 cols) | ✓ yes | |
| Regional indicator flags (2 cols) | ✗ no | Emoji flag sequences not rendered as wide characters |
| Variation selector 16 (emoji presentation) | ✗ no | VS16 emoji variation selectors not handled |
| Emoji ZWJ sequences (2 cols) | ✓ yes | |
| Text wraps at width | ✓ yes |
Unicode
| Feature | Support | Notes |
|---|---|---|
| East Asian Ambiguous Width | ✓ yes | |
| Grapheme Cluster Cursor Movement | ✓ yes | |
| Tab Stops (HT) | ✓ yes | |
| Wide Char at Line Wrap | ✓ yes |