Instructions Lexi follows in a project
Write your project’s conventions once, such as spelling or citation style, under Instructions for this project in Lexi’s settings. Lexi follows them in every reply, and everyone on the project shares them.
What’s new in LetX
The changes you would notice, newest first, each dated the day it went live. We list what you can use today, never what is planned.
October 2026
SyncTeX buttons between the code and the PDF
On a computer, the two jump buttons now sit on the divider between the code and the PDF, so going from a line to its place in the PDF, and back, is one click from either side.
Your department’s template on LetX
Faculty and staff can send us their university’s thesis, report or slide template, and we publish it in the gallery, credited to the department. Read more
Open in LetX badge for GitHub
Add the badge to a README and one click opens a public GitHub repository, or one folder of it, as a LetX project, ready to compile. Read more
Import several projects at once
Upload one zip of many Overleaf or Prism projects and each becomes its own LetX project, with its files, folders and main document worked out for you. Read more
Quick project
A second button on the projects page opens a blank project straight away, with no template to pick first.
Better main document detection
An imported project now opens on the file that really builds the document, not on a chapter that happens to contain \documentclass in a comment or an example.
Moving from OpenAI Prism
OpenAI closes Prism on January 1, 2027. The guide shows how to export every project and bring them all into LetX in one upload. Read more
New tags from the sidebar
The Tags list in the projects sidebar ends with New tag: name it, tick the projects it goes on, done.
Public pages load faster on phones
The homepage and other public pages download far less before their buttons respond, which matters most on a mid-range phone on a slow connection.
Lexi shows only the lines it changes
Reviewing an edit from Lexi now previews, and accepts, only the lines it changed, instead of marking larger blocks around them.
Faster builds after typing
A build starts on what you just typed without waiting on a pause first. A PDF you uploaded with the same name as your document is never shown in place of the build.
Connect Codex
Codex now signs in to LetX with one command, codex mcp add, alongside Claude and ChatGPT. Read more
Spanish, Arabic, Japanese, Korean and Simplified Chinese
The website and the app are now available in five more languages, with Arabic laid out right to left. Pick yours from the language menu.
Vim keys
Turn on Vim keybindings from the editor’s Appearance menu or Settings. Undo follows the shared document, so it never takes back a collaborator’s edit.
Undo in shared documents
Cmd-Z or Ctrl-Z in a document several people are editing undoes your own last edit, never someone else’s.
Go to code from the bibliography and title
Clicking a reference in the PDF opens your .bib file at that entry, and clicking the title block goes to where it is written.
Beamer theme gallery
Every common Beamer theme side by side, each one ready to open in LetX. Read more
Small caps, and a comment button that comments everything
Cmd or Ctrl+Shift+C sets small caps. The comment button now comments every selected line, indented ones too, exactly like Cmd or Ctrl+/.
Formatting shortcuts in the editor
Bold, italic and the other formatting commands each have a keyboard shortcut, listed in the toolbar’s tooltips.
Claude connector: a free week to try it
Free accounts can use the LetX connector in Claude for 7 days from their first connection. Read more
WebP images that pretend to be PNG or JPEG
An image saved as .png or .jpg that is really WebP is converted so it builds, and an image LaTeX cannot read is named in the error.
XeLaTeX and LuaLaTeX fixes
XeLaTeX builds are quick again, LuaLaTeX finds system fonts by name, and a stale cached PDF is no longer shown after a change.
A security fix to the build servers
Builds now ignore configuration files inside a project that could change how the build server runs. Projects that use nomencl build again.
Video lessons in the LaTeX courses
Both Learn courses now have video lessons, with chapters you can jump to. Read more
Selections show in every editor theme
A selection made with the mouse is visible on the line you are editing too, in light, dark and every editor theme.
Dark mode
Dark mode for the whole app and site, plus editor themes, fonts, sizes and line height, all from the Appearance menu. Your choice follows you to other devices.
The Team plan
Labs, groups and classes of 2 to 50 people can buy Pro seats on one bill, give and take seats any time, and see an activity log. Read more
Paid builds never wait behind free ones
Builds on Pro, Team and Institution plans run in their own lane on the build servers.
German
The website and the app are available in German.
Ctrl+Enter to build, and spell check on by default
Ctrl+Enter or Cmd+Enter builds the document. Lexi can move below the PDF and be dragged to any height, and LetX’s own spell check is on from the start.
Public numbers that count themselves
The figures on the stats page and the homepage come straight from the live count every time the site is built, never typed by hand. Read more
Older iPads and Macs
Projects open on older versions of Safari on iPad and Mac, which could not show the PDF before.
SyncTeX lands on the word you clicked
Clicking in the PDF puts the cursor on the word you clicked, also in multi-file and A4 projects, with jump buttons and a highlight that fades.
Saves on slow connections
One save at a time per document, and a save that stalls now times out instead of hanging.
September 2026
Two-way GitHub sync
Pull changes from GitHub and push your edits back, on Pro. Files with Windows line endings edit correctly.
A failed Lexi run is not charged
When Lexi fails without changing anything in your project, the run does not count against your allowance.
Pick your university from a list
Choose your university or lab from a list when you set up your profile, instead of typing it.
French, and GitHub pushes back to its own repository
The website and the app are available in French. A project imported from GitHub pushes back to the repository it came from.
No more duplicate files
A project can no longer hold two files at the same path, which could make one author’s work vanish from the PDF without an error.
Choosing LetX for a group or a department?
The security page says where your data is stored, who processes it and what we do not have yet. Plans for groups are on the pricing page.