Run a server on localhost with a locally-trusted SSL certificate. Serve static files, proxy an existing server, define your own routes, or import it as a module in your project.

The certificate is provided by mkcert. It automatically creates and installs a local CA in the system and browser root stores, and uses it to generate certificates that your machine trusts. These are not valid certificates, they are for development only, and will only work in your machine.

Certificates support macOS, Linux and Windows. The full list of supported root stores is available in the original repo.

# install
npm i -g https-localhost

# run
serve ~/myproj

Usage notes:

• sudo may be necessary.
• If a static path is not provided the current directory content will be served.
• CLI flags override environment variables:
  • -p, --port <port>: port to listen on (PORT)
  • -H, --host <host>: domain for the certificate (HOST)
  • --cert-path <path>: custom certificate directory (CERT_PATH)
  • --reinstall: force certificate re-generation (REINSTALL=true)
  • --proxy <url>: proxy all requests to the given http(s) URL (PROXY_TARGET)
• Specifying a port number prevents HTTP to HTTPS redirect.

Install as a dependency:

npm i -D https-localhost

Then use it to serve static files or proxy an existing server.

import { createServer } from "https-localhost"
// or, in CommonJS:
// const { createServer } = require("https-localhost")

const app = createServer()
await app.redirect() // enable http -> https
await app.serve(path) // serve static files

// or, instead of serve, proxy an existing server:
await app.proxy("http://localhost:3000")

Alternatively, you can use the certificates in your own server:

import https from "node:https"
import { getCerts } from "https-localhost/certs" // or: const { getCerts } = require("https-localhost/certs")

const certs = await getCerts()

https.createServer(certs, (_, res) => res.end("Hello, world!")).listen(443)

Uninstalling the npm package removes the generated certificates automatically.

• At first run this tool generates a trusted certificate. The sudo password may be required. If you cannot provide the sudo password generate a localhost.key and localhost.crt and specify its path with CERT_PATH=/directory/containing/certificates/ serve ~/myproj.
• At each run the password may be required to run the server on port 443 and 80. To avoid the script ask for password specify a different port number: PORT=4433 serve ~/myproj.

Run with sudo to use the default ports 443 and 80. You can also change port with: PORT=4433 serve ~/myproj.

Another service on your machine is using port 443 or port 80. Stop it or change port with PORT=4433 serve ~/myproj.

And in general all the cases when the script runs but the connection is marked as untrusted.

Force a reinstall of the certificate with REINSTALL=true serve. sudo may be required on linux and MacOS.

If the problem is solved you should be able to use https-localhost as a module too.