A text editor that looks like a printed page, not a terminal application.
curl -sSL https://raw.githubusercontent.com/davidemerson/issy/main/install.sh | shOne line. Drops issy at ~/.local/bin/issy, verifies an Ed25519 signature over the release manifest, seeds ~/.issyrc with commented defaults if you don't already have one, and wires up the opt-in auto-update path. Works on Linux (amd64/arm64) and OpenBSD amd64 with a prebuilt binary; macOS falls through to a zig build from source. Full install options →
Built in Zig with zero external dependencies. Single binary, around 700KB in ReleaseSafe. Gap-buffer text storage with an O(1) line index, syntax highlighting for 20 languages (including TeX/LaTeX), PDF export with real TTF/OTF font embedding and per-token print colors, multi-cursors, undo/redo, incremental search with smart case and live match highlighting, keyboard and mouse selection.
| Default | Paper |
|---|---|
 |
 |
Both follow the same rule: keywords and strings carry the strongest chromatic contrast, a few token types get lighter accents, and the rest sit at body-text luminance, so the eye parses structure through gentle shifts instead of a rainbow. See DESIGN.md for the full visual design notes.
Ctrl+P renders the current buffer to a real PDF 1.4 file with TTF/OTF font embedding, per-token syntax colors from a separate ink-on-paper print theme, a filename + page-number header on every page, and automatic page breaks. Text copied out of the PDF extracts as real characters (a proper ToUnicode CMap, not an identity map). No external dependencies, no temporary PostScript — the PDF writer is hand-rolled in Zig.
Ctrl+D selects the word under the cursor and adds a cursor at the next occurrence. Press it again to keep adding. Every edit — typing, backspace, delete, paste — applies to all cursors simultaneously, and Ctrl+Z undoes the whole multi-cursor tick as a single step.
Ctrl+F enters search mode and each keystroke re-runs the search from where you started, jumping the cursor to the first match at or after that origin. Every visible match is highlighted while the prompt is open, and a dim 3/17-style counter sits after the pattern. All-lowercase patterns match case-insensitively (smart case); any uppercase letter makes the search exact. Down/Ctrl+G walk to the next match, Up walks to the previous one, Enter confirms, and Escape cancels and returns the cursor to where it started.
Shift + arrow extends a selection one character at a time; Ctrl+Shift+Left/Ctrl+Shift+Right grow it a word at a time. Click, double-click (select word), and triple-click (select line) also work, as does shift+click to extend from the existing anchor. Drag past the viewport edge and the view autoscrolls.
Ctrl+O opens the file prompt seeded with the current directory. Type a partial directory or filename and press Tab to complete against what's on disk.
curl -sSL https://raw.githubusercontent.com/davidemerson/issy/main/install.sh | shFlags:
| Flag | Default | Purpose |
|---|---|---|
--prefix DIR |
$HOME/.local/bin |
Target install directory |
--version VER |
latest |
Pin to a specific release |
--no-rc |
off | Skip seeding ~/.issyrc |
--help, -h |
— | Show usage |
Prefer to inspect the script first?
curl -sSL https://raw.githubusercontent.com/davidemerson/issy/main/install.sh -o install.sh
less install.sh
sh install.shHow it decides what to do. On Linux amd64/arm64 and OpenBSD amd64 the installer downloads a prebuilt binary, verifies an Ed25519 signature over sha256sums.txt against a public key baked into the script, then verifies the binary's SHA-256 against that manifest, and finally installs with install -m 0755. On macOS (and any platform without a prebuilt) it falls through to a source build: clones the repo, runs zig build -Doptimize=ReleaseSafe, and installs the resulting binary. Source builds require Zig 0.15.x or 0.16.x on PATH (src/fsx.zig bridges the two series' std APIs; anything else is rejected at compile time with an actionable error).
brew tap davidemerson/issy https://github.com/davidemerson/issy
brew install issyUpgrade: brew upgrade issy. The formula tracks tagged releases (vX.Y.Z), so this is the same one-liner you'd use for any Homebrew package — no --fetch-HEAD, no uninstall+reinstall dance. CI maintains the formula's url + sha256 automatically on every tag push (see .github/workflows/ci.yml → release-tag job).
Want the bleeding edge between releases?
brew install --HEAD issy # build from main
brew upgrade --fetch-HEAD issyThe curl installer also works on macOS — use whichever you prefer.
The curl installer downloads a prebuilt amd64 binary. Builds are verified on every push by a real OpenBSD 7.9 amd64 VM in CI (openbsd-test job, see .github/workflows/ci.yml) — full unit + integration suite must pass on OpenBSD before main accepts a merge. An editors/issy ports submission is in flight; when it lands, pkg_add issy will be the preferred path.
Building from source on OpenBSD: pkg_add zig then zig build -Doptimize=ReleaseSafe. bash and expect (also via pkg_add) are needed if you want to run the integration test suite.
Requires Zig 0.15.x or 0.16.x (CI exercises 0.15.2 and 0.16.0).
git clone https://github.com/davidemerson/issy
cd issy
zig build -Doptimize=ReleaseSafe
install -m 0755 zig-out/bin/issy ~/.local/bin/issyOther build.zig entry points:
zig build # debug build
zig build test # run all tests
zig build cross # build all cross-compile targetsCross-compile targets: x86_64-linux-gnu, aarch64-linux-gnu, x86_64-macos, aarch64-macos, x86_64-openbsd.
issy [options] [file[:line]]
issy main.zig
issy src/editor.zig:42 # open at line 42 (works for new files too: issy draft.md:5 creates draft.md)
issy newdoc.md # start a new file at that path
issy # empty buffer| Flag | Description |
|---|---|
--version, -v |
Print version and exit |
--help, -h |
Print usage and exit |
--config FILE |
Use a specific config file |
--theme NAME |
Override theme (default, paper) |
--font PATH |
TTF/OTF font for PDF output |
--no-config |
Skip loading config file |
--print FILE |
Export to PDF and exit (no TUI) |
--rollback |
Swap in the previous binary (if auto-update has run) and exit |
issy --font /path/to/font.ttf --print output.pdf source.c| Key | Action |
|---|---|
| Ctrl+S | Save — works from every mode: search/replace/help save and return to normal, the unsaved-changes prompt saves and stays, and the Save-As prompt submits |
| Ctrl+Q | Quit (on unsaved changes: Enter or Ctrl+Q again discards, Ctrl+S saves and stays, Escape cancels) |
| Ctrl+Z | Undo (typing runs coalesce within 500ms — one step per word) |
| Ctrl+Y | Redo |
| Ctrl+C | Copy selection (also pushes to OS clipboard via OSC 52) |
| Ctrl+X | Cut selection (also pushes to OS clipboard via OSC 52) |
| Ctrl+V | Paste the system clipboard via OSC 52 (falls back to issy's internal clipboard if the terminal blocks OSC 52 read) |
| Ctrl+A | Select all |
| Tab | Insert tab or spaces (per config) |
| Enter | Newline with auto-indent |
Typing, Tab, or Enter while a selection is active replaces the selection.
Pasting. Ctrl+V reads the system clipboard over OSC 52, so text copied in any other application pastes straight in; if the terminal has OSC 52 read disabled (common over SSH), it falls back to issy's own internal clipboard. Middle-click pastes the primary selection the same way. Your terminal's native paste keys always work too — Ctrl+Shift+V (clipboard) and Shift+Insert (primary selection) — arriving as a bracketed paste (DECSET 2004). However it arrives, pasted text is inserted verbatim as a single undo step: auto-indent is not applied and embedded newlines or tabs never trigger editor commands, so already-formatted content comes in exactly as copied. Set system_clipboard = false in ~/.issyrc to keep Ctrl+V bound to the internal clipboard only.
| Key | Action |
|---|---|
| Arrow keys | Move cursor |
| Ctrl+Left / Ctrl+Right | Jump by word |
| Home / End | Start / end of line |
| Page Up / Down | Scroll by page |
| Ctrl+L | Go to line (prompt for a line number) |
| Mouse scroll | Scroll viewport (cursor stays) |
| Mouse click | Position cursor |
| Double-click | Select word |
| Triple-click | Select line |
| Key | Action |
|---|---|
| Shift + Arrow | Extend selection by character |
| Ctrl+Shift + Left/Right | Extend selection by word |
| Shift + Home / End | Extend to line start / end |
| Shift + Click | Extend selection to click position |
| Click + drag | Extend selection (drag past edge to autoscroll) |
| Escape | Clear selection and extra cursors |
| Key | Action |
|---|---|
| Ctrl+F | Incremental search (Escape cancels, Enter confirms) |
| Up / Down (in search) | Previous / next match |
| Ctrl+G | Find next match |
| Ctrl+H | Search and replace (Tab switches fields, Enter replaces next, Ctrl+A replaces all — one undo step) |
Search is smart-case: all-lowercase patterns match case-insensitively, any uppercase letter makes the match exact. While the search prompt is open, every visible match is highlighted (the one at the cursor is underlined) and a current/total counter is shown after the pattern; Tab toggles whole-word matching (shown as [w]). Each keystroke re-runs the search from the position where you pressed Ctrl+F.
| Key | Action |
|---|---|
| Ctrl+O | Open file (on unsaved changes, prompts for confirmation) |
| Ctrl+N | New empty buffer (on unsaved changes, prompts for confirmation) |
| Ctrl+P | Export to PDF (requires font_file in config or --font) |
| Ctrl+R | Reload file from disk (on unsaved changes, prompts for confirmation) |
| Ctrl+W | Same as Ctrl+Q |
If the open file changes on disk (a git pull, another editor), the status bar shows File changed on disk. Ctrl+R to reload. — even while issy is idle. Opening, reloading, or starting a new buffer clears the undo history, since it refers to the previous content.
While a buffer has unsaved changes, issy periodically writes them to a sibling .<name>.swp file (removed on save or clean exit); if you reopen a file and a leftover swap from a crashed session is found, the status bar points you to it. Turn this off with swap_files = false. Optional editing aids off by default: auto_close_brackets (type ( to get () with the cursor between, wrap a selection, step over closers, delete empty pairs) and wrap_indent (soft-wrap continuation rows hang under the line's own indentation).
| Key | Action |
|---|---|
| Ctrl+D | Select word under cursor; press again to add cursor at next occurrence |
| Escape | Clear all extra cursors and selection |
All editing operations apply to every cursor simultaneously, and Ctrl+Z undoes the whole tick.
| Key | Action |
|---|---|
| Ctrl+/ | Show keybindings overlay |
| F1 | Same as Ctrl+/ |
The installer seeds ~/.issyrc on first run with every setting commented out, so you can see what's available and uncomment what you want. Unknown keys are ignored; missing keys fall back to compiled-in defaults.
See CONFIGURATION.md for the full reference, or copy examples/issyrc as a starting point. Quick taste:
tab_width = 4
expand_tabs = true
line_numbers = true
right_margin = 100
cursor_style = bar
font_file = "/path/to/font.ttf"
[theme.paper]
Quit a file and issy remembers the cursor position at ~/.cache/issy/positions.txt; reopening the same file restores the caret automatically. Positions are keyed by absolute path, capped at 300 entries with an LRU-ish "newest on top" layout, and lose gracefully (corrupt file or missing HOME is a silent no-op). Explicit file:line on the command line always wins over the saved position.
C, C++, Zig, Python, JavaScript, TypeScript, Rust, Go, Ruby, Java, Shell, HTML, CSS, JSON, YAML, TOML, Makefile, Dockerfile, Markdown, TeX/LaTeX. Language is detected by file extension or well-known filename (Makefile, Dockerfile, Gemfile, shell dotfiles like .bashrc). Multi-line constructs carry across lines — C block comments, Python triple-quoted strings, JS/TS template literals, and Zig \\ line strings all highlight correctly, including when their opening delimiter is scrolled off-screen.
Files whose lines all end in CRLF are normalized to LF in memory and written back with CRLF on save, so Windows-authored files round-trip byte-for-byte without showing stray carriage returns. Files with mixed endings are left untouched.
Ctrl+P exports the current buffer to a PDF 1.4 file alongside it (same directory, .pdf suffix). --print output.pdf source.c does the same headlessly without opening the TUI. Both require a TTF or OTF font file via font_file in config or --font on the command line. PDF output uses a print theme with per-token syntax colors tuned for ink on white paper — it never inherits the TUI theme — and each page carries a filename + page-number header when the top margin has room for one.
Recommended fonts: Berkeley Mono, Iosevka, JetBrains Mono, Commit Mono.
Release builds check the latest GitHub release on startup via a detached background worker, so the editor itself never blocks on the network. If the release's commit SHA differs from the one the running binary was built from, the footer shows update available: <sha>.
Opt into automatic download and in-session re-exec by setting autoupdate = true in ~/.issyrc. With auto-apply on, the worker downloads the signed manifest, verifies the Ed25519 signature against src/update_key.zig, checks the manifest's embedded commit and monotonic epoch (so a replayed older release — authentic but stale — is rejected as a downgrade), hashes the platform binary against the manifest, and stages it at ~/.cache/issy/issy.staged. The next time the buffer is clean and the editor has been idle for 60 seconds, the staged binary is re-verified against the cached signed manifest, atomically swapped over the running binary, and execve()d with a one-shot --resume record that restores the cursor position. Rollback any time with issy --rollback (the snapshot's recorded checksum is verified first).
Dev builds skip the check entirely; only ReleaseSafe builds produced by CI participate. Root-owned installs silently fall back to notify-only (the worker refuses to overwrite root-owned binaries).
See ARCHITECTURE.md for the full flow, the cache layout, and the signing-key bootstrap procedure for forks.
- ARCHITECTURE.md — tour of the source code and the major subsystems
zig build test— 258-test unit suite (gap buffer, Unicode, tokenizer, editor operations, mouse/selection, search, auto-close, swap files, update verification, hostile-input hardening, etc.); each source file compiles and runs as its own test unit, so imported modules' tests re-run per unitbash tests/run_tests.sh— end-to-end integration suite viaexpect, launches the real binary in a PTYman ./issy.1— man page
BSD 3-Clause