A live LaTeX preview for VS Code that keeps up with your typing. It is built on
realtime-tex (rtex), which keeps LuaTeX running and
re-typesets only the paragraph you are editing, in about a millisecond. Page breaks,
references and bibliographies follow from a full compile in the background.
Quick start
Open a folder with a LaTeX project. Linux, macOS and Windows are supported.
Open a .tex file and click the preview icon in the editor title bar, or press Ctrl+Alt+V (Cmd+Alt+V on Mac).
Start typing.
On first use, the preview walks you through anything that is missing:
rtex is not installed. Click Install rtex. It downloads the prebuilt engine of the latest realtime-tex release for your platform (a few MB) and checks its SHA-256. Prefer to build it yourself? Build from Source clones realtime-tex main and builds it with Rust's cargo (a few minutes; on Windows it also needs Git for Windows and the Visual Studio C++ Build Tools that rustup asks for). The realtimeTex.installFrom setting picks which one Install rtex does.
LuaLaTeX was not found. Choose your TeX Live bin folder, or let the extension install a minimal TeX Live 2026.
Realtime TeX: Check Setup in the command palette checks everything and offers a fix for each problem.
The extension keeps the rtex it installed up to date, the way it was installed: a downloaded rtex updates to the latest release, one built from source pulls realtime-tex main and rebuilds it. It checks once a day and offers Update Now; Realtime TeX: Update rtex Engine updates on demand and restarts the engine. The realtimeTex.updateCheck setting controls this.
Using the preview
Toolbar
Status pill · zoom − / + · Fit width · Follow cursor · Recompile · Export PDF
Status pill
Live · 0.8 ms means the paragraph was re-typeset that fast. Updating layout… means a full compile is placing pages, references and floats. Up to date means everything matches. N errors opens the Problems panel.
Live markers
A bar next to the line numbers shows how each part of your source updates: solid green updates live as you type, dotted amber waits for the full compile (the preamble, TikZ, …). Hover over a part that went to the full compile to see why.
Follow cursor
The preview scrolls to the paragraph you are editing. Ctrl+Alt+J jumps there on demand.
Jump to source
Double-click (or Ctrl/Cmd+click) a paragraph in the preview.
Zoom
Ctrl + mouse wheel, Ctrl + = / − / 0
Export PDF
Ctrl+Alt+E. Writes main.pdf next to the main file. The result matches a clean LuaLaTeX build.
Errors
LaTeX errors and warnings appear in the Problems panel and as squiggles.
The main file is found automatically. The extension looks for, in order:
a % !TEX root = main.tex comment;
the file with \documentclass;
the file that \inputs or \includes the one you are editing.
If it is ambiguous, the preview asks you to choose. The choice is saved in realtimeTex.mainFile.
To look at one part of a project on its own, run Preview This File Only (editor or explorer
context menu). A file with its own \documentclass is previewed as it is. A file without one (a
chapter, a section) is wrapped in realtimeTex.previewTemplate, by default a plain article;
add the packages and macros your parts need there. Its paths resolve from the main file's folder,
as in the whole document. While that preview runs, the wrapper is a hidden .rtex-preview.tex in
that folder.
What updates instantly
Body text, inline and display math, \ref/\eqref/\cite (with the numbers from the last
full compile), lists, theorems, figures and tables (content), and headings all update with each
keystroke. Everything else updates with the next full compile, typically a second or two later:
preamble changes;
TikZ;
moved floats;
footnote text at the bottom of the page;
new page breaks.
The pill says when this is happening. See rtex's
live editing guide for details.
For the fastest updates, use TFM fonts (the default, lmodern, …) or OpenType fonts loaded with
Renderer=Basic. fontspec's default node mode works, but each keystroke takes longer.
How pages are drawn
The preview draws rtex's display lists itself, so a keystroke repaints a single paragraph without a
PDF round trip. It supports:
OpenType/TrueType fonts, by glyph index;
Type1 fonts, such as Computer Modern math and lmodern, found through TeX's pdftex.map;
colors, rules, PNG/JPEG/PDF images and graphicx scaling.
Some pages cannot be drawn this way, for example TikZ drawings or \specials. Those are shown
from the background PDF, marked with a small from PDF badge, and edits on them still appear
live on top.
Settings
Setting
Default
realtimeTex.serverPath
(auto)
rtex binary. Empty means the one installed by Install rtex, then rtex on PATH.
realtimeTex.texliveBin
(PATH)
Folder containing lualatex.
realtimeTex.texDir
(auto)
rtex's tex/ support files. Only needed if you moved the binary away from them.
realtimeTex.installFrom
release
What Install rtex does: release downloads the prebuilt engine, source builds realtime-tex main with cargo.
realtimeTex.updateCheck
notify
Once a day, check for a newer engine (a new release, or new commits on main for a source build): notify offers the update, auto updates by itself, off never checks. The setting has an Update rtex now link.
realtimeTex.engine.eligibility
probe
How rtex picks the parts that update live: probe (compare a live result with the last full compile) or allowlist (only known-safe commands).
realtimeTex.engine.fastBudgetMs
50
Time budget for re-typesetting one part live; a part that takes longer three times in a row waits for the full compile.
realtimeTex.engine.pictureCache
true
Reuse unchanged TikZ pictures from the previous full compile.
realtimeTex.debug.enabled
false
rtex saves a debug bundle (source, context, trace, TeX log) whenever the live engine hangs or crashes, and lists every live compile in requests.log. Open Debug Folder shows them.
realtimeTex.debug.directory
(storage)
Where debug bundles go.
realtimeTex.mainFile
(auto)
Main file, relative to the workspace folder.
realtimeTex.previewTemplate
(article)
The document Preview This File Only wraps around a file without \documentclass; ${file} is the file's path.
realtimeTex.buildDir
(storage)
Where rtex keeps build files. Empty keeps them out of your project.
realtimeTex.exportPath
${mainDir}/${mainName}.pdf
Where Export PDF writes.
realtimeTex.syncCursor
true
Preview follows the cursor.
realtimeTex.editor.liveMarkers
true
Live/full-compile bars next to the line numbers.
realtimeTex.autoStart
false
Start the engine when a LaTeX file opens, without waiting for the preview.
realtimeTex.stopWhenPreviewCloses
true
Stop the engine when the preview closes.
realtimeTex.preview.zoom
fitWidth
Initial zoom.
realtimeTex.preview.invertInDarkTheme
false
Dark pages in dark themes.
Commands
All commands are under Realtime TeX: in the command palette:
Open Live Preview to the Side
Preview This File Only
Export PDF
Recompile Whole Document
Show Cursor Position in Preview
Restart Engine
Stop Engine
Show Log
Open Debug Folder
Check Setup
Install rtex
Install rtex (Build from Source)
Update rtex Engine
Locate rtex Binary…
Choose Main File…
Get Started
Development
npm install
npm run build # dist/extension.js, dist/webview.js
npm test # unit tests (node:test)
npm run typecheck
npm run package # .vsix
Press F5 in VS Code to start an Extension Development Host.
The integration suite drives a real VS Code with the real engine. It needs a built rtex and
TeX Live:
RTEX_E2E_SERVER=/path/to/realtime-tex/target/release/rtex \
RTEX_E2E_TEXLIVE_BIN=/path/to/texlive/2026/bin/x86_64-linux \
xvfb-run -a npm run test:e2e
On macOS and Windows, run npm run test:e2e without xvfb-run. The E2E workflow runs the suite on
Linux, macOS and Windows against the latest realtime-tex.
Releasing
Set version in package.json and add a ## <version> section to CHANGELOG.md, then push a
matching tag:
git tag v0.0.1 && git push origin v0.0.1
The Release workflow builds the .vsix, checks that the tag matches package.json, and
creates the GitHub release with the changelog section as notes and the .vsix (plus its
SHA-256) attached. Publishing a release in the GitHub UI, or running the workflow by hand with a
tag, attaches the .vsix to an existing release.
