CLI

The harp command-line interface has two forms: one to serve a project locally, and one to compile it to a directory of static files.

Serve a project

harp <source>

Pointing harp at a directory starts a local web server that serves that directory. The directory you point at is the served root — its name doesn't matter. public/, src/, mysite/, anything works.

harp ./mysite
# Serving at http://localhost:9000

You can also serve the current directory:

harp .

While the server is running, edit your templates and refresh your browser to see changes.

Flags

harp ./mysite --port 3000
harp ./mysite -p 8080 --silent
harp -v

Compile to static assets

harp <source> <build>

Add a second argument to compile the project to a directory of static HTML, CSS, and JavaScript:

harp ./mysite ./www

The output directory is created if it doesn't exist. Templates are rendered to their final extensions:

• .ejs, .md, .jade → .html
• .sass, .scss, .less, .styl → .css
• .coffee, .cjs, .jsx → .js

All non-source files (images, fonts, plain .html, video, etc.) are copied through unchanged. Underscore-prefixed files — _layout.*, _partials/*, _data.json, _harp.json (or legacy harp.json) — are not emitted; they're build-time only.

The compiled output is deployable to any static host: Amazon S3, Netlify, GitHub Pages, Cloudflare Pages, or your own server.

Production mode

Set NODE_ENV=production to enable additional caching and to flag the build as production:

NODE_ENV=production harp ./mysite
NODE_ENV=production harp ./mysite ./www

Inside any template, the environment variable resolves to "production" (or "development" otherwise), and globals.environment is set the same way. This is useful for switching analytics scripts, asset URLs, or feature flags between environments:

<% if (environment === "production") { %>
  <script src="/analytics.js"></script>
<% } %>

See Environment for more on the runtime environment variable.

Notes

• Direct requests to source files are blocked. /about.md returns 404; only the rendered URL /about works.
• The dev server has no live reload — refresh your browser to see changes.
• Underscore-prefixed files and directories (_layout.ejs, _partials/, _data.json, _harp.json) are never served and are excluded from the compiled output.
• To embed Harp inside an existing Express application instead of running it as a CLI, see Lib.