The short version
Scissor LaTeX never receives your work. When you open a tool, your browser downloads the website and its engines. What you type, paste or open stays in the memory of your tab; the tool works on it there, on your own processor, and the result is yours to copy, download or save to your Google Drive. Closing a tool's tab erases what you did not save. The editor keeps your projects in this browser until you delete them.
What runs where
The core engine converts LaTeX to MathML, HTML and Markdown, formats and converts BibTeX, makes citation keys and builds tables. It is written in Rust and compiled to WebAssembly, so it runs inside your browser at close to native speed.
The typesetter turns equations into PNG, SVG and PDF. It translates LaTeX math with mitex and lays it out with the Typst compiler, using the New Computer Modern fonts, the modern version of the fonts LaTeX itself uses. It is about 9 MB. On your first visit your browser downloads it in the background and keeps it for offline use, and after the site is updated it downloads the new version once. Fonts for other writing systems, such as Greek, Arabic or Chinese, are downloaded the first time a document uses them.
The server hosts the site's files and has no endpoint for your documents. A small customer care service on the same domain automatically receives page counts and short error reports, plus anything you choose to send it, such as feedback, a bug report or a screenshot.
The AI models are optional. If you download one in the editor's AI panel, your browser fetches it once from this site (about 0.5 to 1.1 GB, depending on the model) and keeps it in this browser. It runs on your device's graphics chip with WebGPU; your documents and what you ask it are not sent anywhere.
Google Drive
Open from Drive and Save to Drive use Google's own sign-in and file picker. Google asks you to allow access to files you open or create with Scissor LaTeX (the drive.file permission), not to the rest of your Drive. The access token stays in your tab's memory and is forgotten when you close it. Files travel directly between your browser and Google.
Verify it yourself
Open your browser's developer tools, switch to the Network tab and use any tool. You will see the page's own files load, small page-count requests to /_care/, and no request carrying your work. On your first visit you will also see your browser store the engines and fonts for offline use. If you use Google Drive, you will also see requests to Google, and only to Google. You can also disconnect from the internet after your first visit: every tool and the editor keep working. Google Drive, and fonts for other writing systems and some layouts that you have not used yet, need a connection.
The site sends a strict Content Security Policy that tells your browser to block the page from contacting any server other than this site and Google's sign-in, picker and Drive services.
Open-source components
The engines are built on open-source software that allows use in closed products: Typst, mitex, math-core, hayagriva and biblatex (MIT or Apache 2.0), the Latin Modern and New Computer Modern fonts (GUST Font License) and the Citation Style Language styles (CC BY-SA 3.0). Their notices are on the licenses page.
The optional AI panel uses WebLLM (Apache 2.0) to run the Qwen3.5 models (Apache 2.0) in your browser. Their notices are on the licenses page too.