Kaset [kaˈset] is an open source toolkit to build browser-first, agentic web apps.

Docs • Playground • Issues • MIT License

Kaset is in early development, join our discussions and help shape it.

Introduction

Programming has always been a prelude: developers write code, ship it, and users consume it.

Now imagine your average user being able to create plugins for your web app on the fly.

No coding experience required.

Directly inside your app.

Curious? Check out our documentation.

Contents

• Packages overview
• Local development
• Docs site

Packages

@pstdio/kas

A simple coding agent for the browser.

@pstdio/opfs-hooks

React hooks for working with the browser's Origin Private File System.

@pstdio/opfs-utils

OPFS helpers: ls/tree, grep, safe file reads (text/binary/SVG/PDF), patch utilities.

@pstdio/opfs-sync

Two‑way sync between OPFS and a remote S3 like provider (Supabase adapter included).

@pstdio/prompt-utils

Prompt/JSON helpers for LLM workflows.

@pstdio/tiny-ai-tasks

AI task building blocks: streaming LLM tasks with tool calls, a minimal agent loop, history truncation/summarization, and scratchpad utilities.

@pstdio/tiny-plugins

Plugin runtime for OPFS-backed plugins with manifest validation, command routing, and settings persistence.

@pstdio/tiny-tasks

Composable, interrupt-friendly workflows for TypeScript/JavaScript. Pause, persist, and resume long-running work.

@pstdio/tiny-ui

Browser-first plugin runtime that compiles OPFS sources with esbuild-wasm and exposes host capabilities to plugin iframes.

@pstdio/tiny-ui-bundler

Service worker bundler and runtime asset manager for Tiny UI plugins.

@pstdio/describe-context

Generate an LLM‑ready Markdown context for a folder (library + CLI).

Local development

Requires Node.js 22 (see Volta pin in package.json). From repo root:

npm i               # install
npm run build       # build all packages (lerna)
npm run test        # run all tests

Helpful scripts:

• npm run format • npm run format:check
• npm run lint
• npm run clean
• npm run reset:all (clean → install → lint → build → test)

Per‑workspace examples:

npm run build --workspace @pstdio/opfs-utils
npm run test  --workspace @pstdio/opfs-sync

Docs site

VitePress site lives in clients/documentation/.

npm run start --workspace documentation   # dev server
npm run build --workspace documentation   # static build

License

MIT © Pufflig AB. See LICENSE.