/nitro

Assets

Nitro handles three asset kinds: public assets served directly to clients, imported files inlined into the bundle, and server assets bundled into the server for programmatic access via the storage layer.

Public assets

Files in public/ are served automatically at the matching URL.

public/
  image.png    -> /image.png
  robots.txt   -> /robots.txt

• Served with automatic ETag / Last-Modified and 304 Not Modified support.
• In production, public/ is copied to .output/public/ and a metadata manifest is embedded for fast lookups + caching headers.

Custom public directories

import { defineConfig } from "nitro";

export default defineConfig({
  publicAssets: [
    {
      baseURL: "build",       // served under /build/
      dir: "public/build",    // source on disk
      maxAge: 3600,           // Cache-Control: public, max-age=3600, immutable
    },
  ],
});

Other entry options: dir (relative to rootDir), fallthrough (continue to handlers when not found; defaults true for root, false otherwise) and ignore. maxAge only applies when fallthrough is false.

Pre-compression

Generate gzip/brotli/zstd variants at build time, served based on Accept-Encoding:

export default defineConfig({
  compressPublicAssets: true, // or { gzip: true, brotli: true, zstd: false }
});

Only compressible MIME types ≥ 1 KB are compressed (.map files excluded; zstd needs Node 22+ at build time).

Importing files

Inline any file into the server bundle with an import attribute (base64-encoded for binary). Prefer server assets for larger files.

import logo from "./logo.png" with { type: "bytes" }; // Uint8Array
import readme from "./README.md" with { type: "text" }; // string
// or the raw: prefix
import logo2 from "raw:./logo.png";   // Uint8Array
import readme2 from "raw:./README.md"; // string

Server assets

Files in assets/ (relative to serverDir when set, else project root) are bundled into the server and read via the storage layer at the assets:server mount point (only included in the bundle when accessed through useKV).

assets/
  data.json
  templates/welcome.html

import { defineHandler } from "nitro";
import { useKV } from "nitro/kv";

export default defineHandler(async () => {
  const serverAssets = useKV("assets:server");
  const keys = await serverAssets.getKeys();
  const data = await serverAssets.getItem("data.json");
  const meta = await serverAssets.getMeta("data.json"); // { type, etag, mtime }
  return { keys, data, meta };
});

Custom server asset directories

import { defineConfig } from "nitro";

export default defineConfig({
  serverAssets: [
    { baseName: "templates", dir: "./templates" },
  ],
});

Access via the assets:templates mount:

const html = await useKV("assets:templates").getItem("email.html");

Entry options: baseName, dir (relative to rootDir), pattern (default **/*), ignore.

Key Points

• public/ → served to clients with ETag/compression; assets/ → bundled, read via useKV("assets:server").
• Server assets are only bundled if referenced through useKV (v2 useStorage).
• In dev, server assets read from the filesystem; in production they are inlined with precomputed metadata.
• Use publicAssets[].maxAge and compressPublicAssets to offload caching/compression without a CDN.