> [!tldr] A web app built to run locally and do things. Somewhat surprisingly, a Single File Web App (SFWA) is *(perhaps)* the most [[Durable File Types]] for *apps*. The web's number 1 rule is 'don't break the web'. Thus, any **self-contained** HTML, CSS, and JavaScript file from any point in time should be able to run so long as browsers exist. A SFWA is the encapsulation of a *verb* into a [[Portable Modular Object]]. > [!warning] Dependency Free: the way to be > Web Apps that pull dependencies from [[Easy CDNs|CDNs]] and other external sources **do not count** as "single file" Single File Web Apps are the [[SQLite]] of applications. You can bake them into a [[Progressive Web App]] to get the best of both worlds. [See my Multitool Git repo](https://github.com/aarongilly/multitool). From the "God's Art" source - which honestly [you should read](https://gods.art/articles/single_file_web_apps.html): ## [[Simplicity]] incarnate Compare: ![[Pasted image 20260706123657.png]] ... and in many cases you don't even need the server part of that. To: ![[Pasted image 20260706123714.png]] ## Examples - A **huge** set of these at https://tools.simonwillison.net/colophon - The dude who made [[Datasette]] was way out ahead of me on this idea again! (see source from [[Other Bloggers|Simon Willison]]) - [[TiddlyWiki]] - https://squoosh.app - built by google - [[Excalidraw]] → https://docs.excalidraw.com/docs/introduction/development - [[CyberChef]] - https://hypervault.github.io **** # More ## Source - self, then run down with chatGPT - https://simonwillison.net/2025/Dec/10/html-tools/ - Best practices: https://simonwillison.net/2025/Dec/10/html-tools/ - https://gods.art/articles/single_file_web_apps.html