Writing LaTeX in Japanese usually costs you the first half hour in engine selection and font configuration. Cloud LaTeX is a free online LaTeX environment, run by the Japanese company Acaric, whose design starts from the premise that that half hour should not exist. Register, create a project, type jsarticle and some Japanese, press the compile button, and a PDF appears. This page is about using Cloud LaTeX itself: who runs it and why, why Japanese typesets untouched, the library of more than a hundred templates (科研費 LaTeX, the KAKENHI grant-application forms, among them), the limits the server imposes, and the three routes back out — Dropbox sync, the VS Code extension, and public view-only links. Whether to work in the cloud at all belongs to another page.
Who runs Cloud LaTeX, and why it is free
It is operated by the Cloud LaTeX Team at Acaric Co., Ltd. Why it is free is stated plainly in the service’s own FAQ: Acaric’s actual business is the recruitment site “Acaric”, a career-support service for graduate students and researchers, and since 22 September 2022 the Cloud LaTeX sign-up form has offered the option of registering with that recruitment site at the same time. If you take it, the username there is generated at random, and the two sets of account information are managed separately. The people who use LaTeX daily and the people enrolled in master’s and doctoral programmes are very nearly the same population. Running a free LaTeX environment and keeping a relationship with that population for several years is a coherent investment — and it is why the service has never needed a paid tier.
One account-level landmine catches long-standing users. According to the FAQ, from 27 April 2023 a change to the Twitter API means you can no longer register or sign in with an X (formerly Twitter) account. Anyone who signed up that way can still get in through “password reset” provided the registered email address is still alive; if the address is dead too, the only route left is contacting support. This is exactly the wall people hit when they want to retrieve a project they created years ago and have not touched since — so if that describes you, confirm you can still sign in before you actually need to.
Why Japanese typesets with no configuration
Because the default compile engine on the server is platex. Cloud LaTeX’s own “how to use” page describes the project settings, reached from the hamburger icon on the preview pane, as the place where you can change the compile engine from platex to something else. The starting point, in other words, is already a Japanese one, and the usual barrier — a blank or garbled PDF the first time you type Japanese under pdflatex — simply is not there. Where the international services of the same era were built for English, Cloud LaTeX describes itself as “the first service to natively support Japanese LaTeX”. As for the build environment, the FAQ states it plainly: compilation runs the latexmk command in a frozen (final) TeX Live environment, and at the time of writing that value is TeX Live 2023 frozen. The year is chosen by the operator, not by you, so if a submission guideline demands a particular TeX Live vintage, check the current value in the FAQ before you start writing.
% Paste this into a fresh Cloud LaTeX project and press Compile.
% No engine directive, no font setup, no latexmkrc.
\documentclass{jsarticle}
\begin{document}
\section{はじめに}
日本語がそのまま組めます。数式も同じです:
\[ \int_0^1 x^2 \, dx = \frac{1}{3} \]
\end{document}The platex default also decides how much Japanese actually gets through. pTeX, the engine underneath platex, assumes the JIS X 0208 range and cannot handle characters outside it. Passing platex a line containing 髙 (U+9AD9, the “ladder” variant of 高) on a local TeX Live 2024 stopped with ! LaTeX Error: Unicode character ^^e9^^ab^^99 (U+9AD9) not set up for use with LaTeX. The same line through uplatex did not even raise a warning. So on Cloud LaTeX too, if compilation fails only where a variant character in a personal name or an unusual symbol appears, it is an engine problem and not a font problem. Switch the engine to uplatex in the project settings; because the setting is per project, nothing you have already written elsewhere is affected. Knowing to make that one call changes how often a Japanese manuscript stalls.
Using Cloud LaTeX: the first project, step by step
The screen is in three panes: the file selector on the left, the text editor in the middle, the preview on the right. Create a project from My Page, write in the middle pane, press the compile button at the top right, and the PDF fills the right-hand side. Files are added from the + beside the project name — “new file”, “new folder”, “upload” — or simply by dragging and dropping them in. Once a project has several files, you have to say which one is the document: choose “set target” from the vertical ellipsis (⋮) next to a filename and that file becomes the compile target. This is usually the reason behind “I keep editing but the PDF never changes” after a manuscript has been split into chapters.
Project settings open from the hamburger icon above the preview pane. Besides the compile engine covered in the previous section, that panel carries auto-compile on/off and the editor theme. Auto-compile rebuilds as you type, which is pleasant in a short document but adds waiting to a figure-heavy one. The practical split is to turn it off for a long manuscript and press the button yourself at natural stopping points. The routine below suits the character of this environment: nothing stalls on local setup, but the round trip to the server is now your smallest unit of work, so the more incrementally you build, the better it treats you.
- Start from a blank project or the closest template and compile once before adding anything, to prove the base works.
- Add sections, figures, tables and references one at a time, compiling after each; if it breaks, the cause can only be the last thing you added.
- Drop figures in by drag-and-drop, and keep filenames such as
fig-method.pdfto ASCII letters, digits and hyphens. - Once there are several files, check with “set target” under ⋮ that the compile target is still the main document.
- Download the ZIP of the sources at each milestone so a copy also exists on your own disk.
Templates, and the KAKENHI grant forms
Templates are picked from “create from template” on the project list screen. The site advertises more than 100 of them, and the ones it puts first are the 科研費 LaTeX templates — the application forms for Japan’s Grants-in-Aid for Scientific Research. Alongside them sit academic journal styles, conference poster layouts, technical documents, novels, and even HuiFont, a handwriting-style Japanese font. This is Cloud LaTeX’s most practical strength, and the reason lies in the form itself. A KAKENHI application is a ruled document with fixed box dimensions and a fixed number of lines; add one line in a word processor and the whole layout shifts. It is exactly the class of document that most rewards a typesetting system — and because the official form is revised every year, everything hinges on whether a template tracking this year’s form is available.
What the server limits, and how to get a file back
Compilation runs entirely on the server, so the ceilings are the server’s to set. A single compile has a time limit, and release v2.135.0 (23 Nov 2025) added a warning shown once a build comes within 30 seconds of that limit — which is to say, once you see the warning, the next heavy thing you add is what will break it. Relatedly, v2.133.4 (31 Oct 2025) capped error and warning output at 100 items, fixing a case where projects producing floods of warnings timed out after compiling. On the file side, since v2.65.0 (6 Jun 2022) bulk addition is refused once a project passes 500 files and folders. If you are recompiling heavy tikz drawings on every run, baking them to PDF once and pulling them back with \includegraphics pays off more here than it does locally.
There is also machinery for recovering a file you deleted or a passage you overwrote and regret. Choosing “restore” from the ⋮ beside a filename lists past versions by timestamp; tick one and it comes back. The point worth internalising is that versions are cut when you save, so the habit of saving often is what gives you fine-grained recovery. The retention rule was fixed in v2.104.2 (14 May 2024) as 90 days and the latest 100 versions, which means a version from six months ago is simply gone. On top of that, closing your account deletes the account information and every project (per the FAQ). Downloading the sources as a ZIP became available from the project screen in v2.101.0 (5 Mar 2024), and pulling one at each chapter boundary is the single most effective insurance when working in the cloud.
Dropbox sync, the VS Code extension, and public links
Three routes lead out of the browser. The first is Dropbox sync: as the site puts it, your sources can be synchronised to Dropbox while keeping their folder hierarchy, and the Dropbox integration itself was rebuilt in v2.17.0 (10 May 2019). The second is the VS Code extension, and it is the exit that changes the character of the tool most. Release v2.33.0 (9 Dec 2020) published the official extension as an open-source beta, licensed Apache 2.0. It keeps your local VS Code and the server-side project automatically synchronised in both directions, and compilation runs on the server, so you write in a familiar editor without installing TeX Live locally. It also supports offline editing, syncing automatically once you are back online. Configuration needs only your email address, a client and a token, and the project ID taken from the project URL (123 for /projects/123/edit). Whichever route you use, get into the habit of checking which side holds the newer files, cloud or local, before you start a session: a sync can be a one-way overwrite.
The third route is the public link, and it is surprisingly recent: v2.102.0 (18 Mar 2024) introduced publishing a project. The “Share” button at the top of a project issues a view-only URL, and anyone — including people with no Cloud LaTeX account — can open the project screen through that link with read-only permission. Which is to say that for the several years before this feature landed, Cloud LaTeX was a place to write alone. That is precisely where its character diverges from Overleaf, which was designed around co-editing from the start. It did, though, connect source to PDF early on: v2.14.0 (25 Jan 2019) made it so that after a compile, double-clicking anywhere in the editor jumps the PDF view to the corresponding page — which earns its keep when you are re-reading a long manuscript.
In short, what Cloud LaTeX delivers by the shortest path is two things — Japanese that works from the first keystroke and nothing to set up — with Dropbox and the VS Code extension letting it coexist with local tools on top of that. If the core of your work is several people moving cursors over one manuscript at once, Overleaf suits it better; and once you need to pick the TeX Live year yourself, or you are rebuilding enormous drawings on every run, it is time to install locally. The decision of where to make your home, cloud or machine, is laid out on a separate page.