Overleaf

Overleaf is the most widely used online LaTeX editor today. We leave the “what is it and where did it come from” introduction to the “Try it online” page and focus here on actually using it well — how to create projects, choose the compiler and TeX Live version, set things up for Japanese, and collaborate with others, down to which buttons to press.

Creating a project

Everything happens inside a project. The New Project button at the top left of your dashboard (the project list) opens the ways to start one: Blank Project from scratch, From Template to begin from a gallery starting point, Upload Project to bring in a local .zip, and Import from GitHub. Whichever you pick, you land in the editor afterwards — a file list on the left, the source in the middle, and the compiled PDF on the right.

If you already have a draft on disk, Upload Project is the quick path. Drag a .zip in and Overleaf unpacks it, recreating your folder structure as a project. The catch: the archive may contain only files a LaTeX compiler can process — plain text and images in .eps, .pdf, .svg, or .png — and there is a 7 MB ceiling on the editable material. A Word .docx or a huge dataset will not go in.

If your manuscript lives in Git, Import from GitHub is handy. First link your GitHub account in Account Settings; then you can pick a visible repository from New Project and turn it into a project, after which you can push and pull changes between Overleaf and the repository. Two caveats: Overleaf does not support Git submodules or Git LFS, and a repository that is too large can hit the size limit and fail to import. GitHub synchronization is a paid-plan feature.

Choosing the compiler

Which TeX engine Overleaf uses is a per-project choice. Open the Menu at the top left and, under Settings, you will find Compiler — a dropdown with four options. The default is pdfLaTeX. The choice applies to that project only and does not affect any other project.

The LaTeX entry in the dropdown does not mean raw latex; it means the route that goes through DVI to PDF (calling dvipdfmx internally). That is why its figures are limited to .eps/.ps and you cannot drop in a .png or .jpg directly. Conversely, the Japanese pLaTeX workflow below starts by choosing this “LaTeX.” If you need pstricks, choose LaTeX or XeLaTeX too (LuaLaTeX does not support pstricks).

Right beside it is the TeX Live version setting (also per-project). New projects default to the newest installed release — currently TeX Live 2025. Because Overleaf adopts each new TeX Live a few months after it ships, even after TeX Live 2026 appears in March the default may remain 2025 for a while. Older releases stay selectable as Legacy versions for reproducing a past environment (the oldest may eventually be retired). Which file is the body’s entry point is the Main document setting, changed from the three-dot icon in the file list.

Typesetting Japanese

Overleaf’s default pdfLaTeX cannot set Japanese. Type Japanese with no setup and you get an error or vanished characters. There are two main routes: (1) switch to LuaLaTeX, or **(2) drive pLaTeX/upLaTeX through a latexmkrc**. For a fresh start, LuaLaTeX is the gentler choice — its setup is essentially one line.

The simplest path is to switch the Compiler to LuaLaTeX in the Menu and use a luatexja class. Naming ltjsarticle (a horizontally-set article) or ltjarticle in \documentclass pulls in luatexja for Japanese typesetting. Without an explicit font you get a sensible embedded default, but luatexja-preset lets you embed the IPAex fonts.

% Overleaf: メニュー → Compiler → LuaLaTeX に設定 / set Compiler to LuaLaTeX
\documentclass{ltjsarticle}
\usepackage[ipaex]{luatexja-preset}
\begin{document}
\section{はじめに}
こんにちは、\LaTeX！ 数式も書けます: $e^{i\pi}+1=0$
\end{document}

To write in the pLaTeX workflow common in Japanese journals, set the Compiler to “LaTeX” and add a file named latexmkrc at the project root. Overleaf builds with latexmk, so this is where you tell it to “process with platex, then make the PDF with dvipdfmx.” For upLaTeX, replace platex with uplatex and pbibtex with upbibtex. A newer option is the **jlreq** class, usable with LuaLaTeX, pLaTeX, or upLaTeX.

$latex = 'platex';
$bibtex = 'pbibtex';
$dvipdf = 'dvipdfmx %O -o %D %S';
$makeindex = 'mendex %O -o %D %S';

If you would rather skip this setup, the Japan-made Cloud LaTeX typesets Japanese with no configuration at all — worth considering for a manuscript that is mostly Japanese.

Collaborating

Overleaf’s biggest draw is genuine real-time collaboration. Invite people from the Share button at the top right and you can open the same manuscript together, each other’s cursors and edits appearing live. There are two ways to invite: by email address (choosing Editor or Viewer), or via Link Sharing.

Link Sharing issues two kinds of URL: anyone with the View link can read, and anyone with the Edit link can edit (editing requires creating an account). This is where the limit bites: Viewers never count toward the limit, but Editors consume the project owner’s plan allowance. Past the limit, anyone joining via the edit link drops to view-only automatically.

On the free plan you get one collaborator — you and one other person can co-edit for free. Paid plans raise it: 10 on Standard/Student and unlimited on Pro. In-document comments work on the free plan, but track changes (accept or reject each edit individually) and the full version history (rewind to earlier states) are paid features. For serious multi-author revision, that is usually what tips you toward a subscription.

Using templates

You need not build from a blank page: Overleaf’s gallery holds a vast set of starting points — journals, conference proceedings, CVs, theses, slides, and more. Choose a type from New Project → Templates, or open overleaf.com/gallery directly and click Open as Template on one you like, and a new project springs up in that style.

When you know where you are submitting, journal templates earn their keep. “Official” templates from publishers and societies carry that journal’s rules — its class file and layout — built in, and some let you submit straight from Overleaf once the manuscript is ready. Starting in the right template beats fighting the submission rules later. You can also submit your own template to the gallery.

One practical free-tier note to close on: the compile timeout is 10 seconds, so a long thesis or a heavy TikZ figure can exceed it and time out (240 seconds on paid plans). The fuller free-vs-paid picture, and how Overleaf compares with other services, is gathered on the “Try it online” page.