asset-oven is a lazy, content-hashed asset middleware for Bun — local asset paths written straight into server-rendered HTML just work, no bundler config, no manifest, no build step to remember to run.

I'd previously written a small bundler for Bun + Hono that I've been using on other projects for a while, but recently I've needed to work on more static sites and enjoyed using Hono's server-side JSX for templating, so I ended up writing asset-oven as a weekend project with some help from Claude.

import { Hono } from "hono";
import { builder } from "asset-oven/hono";

const app = new Hono();
app.use(builder({ root: import.meta.dir, publicPath: "/assets" }));

app.get("/", (c) => c.html(`<script src="/client.ts" type="module"></script>`));

export default app;

On the first request that renders /client.ts, asset-oven bundles it with Bun.build, content-hashes the output, rewrites the tag to /assets/client-a1b2c3d4.js, and serves it with a long-lived immutable cache header — all inline in the response, no separate build command.

Quick Start

bun add asset-oven

Pick the adapter for your server:

// Hono
import { builder } from "asset-oven/hono";
app.use(builder({ root: import.meta.dir, publicPath: "/assets" }));

// plain Bun.serve
import { withAssets } from "asset-oven/bun";
const fetch = withAssets(myFetchHandler, {
	root: import.meta.dir,
	publicPath: "/assets",
});
Bun.serve({ fetch });

Then just reference assets by their on-disk path in your HTML — <script src="/client.ts">, <link rel="stylesheet" href="/styles.css">, <img src="/logo.png"> — and asset-oven handles the rest.

Features

• Zero-config asset paths 📝 — write src="/client.ts" in your JSX/HTML like it's a static file; no imports, no manifest to look up.
• Lazy build + hash + cache ⚡ — assets are built on first request, not ahead of time; concurrent requests for the same not-yet-built asset are deduped into a single build.
• Nested assets just resolve 🔗 — a JS import of an image or a CSS url() background produces its own hashed URL automatically, via Bun.build's own dependency graph.
• Real static-file serving 📦 — Range requests, HEAD, and immutable long-lived caching headers, so video/audio scrubbing and CDN caching work correctly.
• Two thin adapters 🔌 — a Hono middleware (asset-oven/hono) and a plain Bun.serve fetch wrapper (asset-oven/bun), both backed by the same framework-agnostic AssetBuilder core.
• Sensible defaults, fully overridable ⚙️ — cache-retry timing defaults off NODE_ENV, and the raw Bun.build config (minify, sourcemap, plugins, define, etc.) can be passed straight through.

Examples

This repo is a Bun workspace monorepo — the library lives in asset-oven/, with three runnable examples under examples/:

• examples/hono-basic/ — a Hono app using the asset-oven/hono middleware
• examples/bun-serve/ — a plain Bun.serve app using the asset-oven/bun withAssets wrapper
• examples/nested-assets/ — a JS import and a CSS url() each resolving to their own hashed asset URL

bun install
cd examples/hono-basic && bun run dev

Swap in examples/bun-serve or examples/nested-assets for the other two.

Configuration

AssetBuilderOptions, accepted by both adapters and the AssetBuilder core:

Option	Default	Description
root	process.cwd()	Directory local asset paths are resolved against.
publicPath	""	Prefix prepended to every hashed asset URL.
cacheDir	a random os.tmpdir() subdir	Output directory for built/copied assets; wiped on boot.
build	{}	Merged into every Bun.build call — e.g. minify, sourcemap, plugins, define.
negativeCacheTtl	60000ms in production, else 5000ms	How long a failed/missing asset lookup is cached before retry.

Testing

cd asset-oven && bun test

License

MIT

🤖 AI Disclaimer

This project uses AI-assisted development tools. All output has been reviewed by a human (me). The overall structure of the project and original prototyping was written by a human.