2026-10-15 02:07 UTCSource content · Analysis pending2 min readUpdated: 2026-10-24 00:45 UTC

LaTeX renderer

Summary

Tool: LaTeX renderer Inspired by Paul Ford and Aboard Foundary's new web app Tiny Little Office, which provides a suite of web app content editors (a Word Processor, Outliner, Presentation Builder, Spreadsheet, Calculator, Drawing Tool, Diagram Maker, Animator, Calendar, and Trip Planner). Tiny Little Office's signature trick is to store all of the document data in the #fragment section of the URL, so every document created using it becomes a bookmarkable and shareable link. It also has an llms.txt file telling agents how to construct URLs that will render as documents. Claude used that file to generate this link to a deck that explains how the URL format works: Tiny Little Office inspired me to have Claude Code (Opus 5.5 Extra) build a similar tool that works with LaTeX. Here's the seque…

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Tool: LaTeX renderer

Simon Willison’s Weblog

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15th October 2026

Tool

LaTeX renderer — LaTeX renderer turns LaTeX source into a rendered view, either a single display equation typeset by MathJax or a full document or prose fragment typeset by faster-latex, with a live preview beside the editor and a toolbar switch between Edit and Rendered views. Source can be typed, loaded from a URL or GitHub Gist, or picked from built-in examples, and the page keeps the LaTeX in the URL fragment so it can be shared as a readable or compressed link.

Inspired by Paul Ford and Aboard Foundary's new web app Tiny Little Office, which provides a suite of web app content editors (a Word Processor, Outliner, Presentation Builder, Spreadsheet, Calculator, Drawing Tool, Diagram Maker, Animator, Calendar, and Trip Planner).

Tiny Little Office's signature trick is to store all of the document data in the #fragment section of the URL, so every document created using it becomes a bookmarkable and shareable link.

It also has an llms.txt file telling agents how to construct URLs that will render as documents. Claude used that file to generate this link to a deck that explains how the URL format works:

Tiny Little Office inspired me to have Claude Code (Opus 5.5 Extra) build a similar tool that works with LaTeX. Here's the sequence of prompts I used:

I want a tool where you can link to it with a fragment hash #code-here and it treats that code as LaTeX and renders it really effectively. It should also support a prefix which means the latex is compressed with a custom compression dictionary optimized for latex. Use the best available latex render library from a CDN (consider WebAssembly too). If loaded without a fragment hash show an editor you can paste latex into and then toggle to a "rendered" view. That rendered view should be bookmarkable. The #fragment view should let you switch to edit source too.

Since it was working in my tools repo I told it to take inspiration from the mechanism used by my existing SVG in Markdown tool as protection against XSS risks:

Safe from XSS? We could run in an iframe sandbox like we do on the SVG markdown render project

I had it copy the Gist/URL loading feature from that tool as well:

We should have an option to load latex from a URL (or gist) similar to the markdown SVG tool

Here's an example link. The tool uses Pako 2.1.0, MathJax 4.1.3, faster-latex 0.3.1, and DOMPurify 3.4.16.

LaTeX renderer

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