How to generate fixed url with ngrok

UPDATE May 2020

Serveo is up and running again! No installation, no signup!

All you need to do is to run this:

ssh -R <unique subdomain>:80:<your local host>:<your local port> serveo.net

like

ssh -R youruniquesubdomain:80:localhost:8000 serveo.net

UPDATE January 2020

Since there are some issues with Serveo and localtunnel, I want to share with you another free ssh-based self-hosting service: Localhost.run

Unfortunately, it does not provide unique subdomains but it is ssh-based so you do not have to install additional applications. Still waiting for Serveo coming back.

UPDATE April 2018

I've found Serveo just now! And it is totally incredible!

UPDATE November 2017

Probably, it is not the best option for you but I started using localtunnel instead of ngrok.

An installation and run flow is very simple:

npm install -g localtunnel
lt --port <your localhost port> --subdomain youruniquesubdomain

Then I can go to my http://youruniquesubdomain.localtunnel.me That's it!

No more free subdomain support from ngrok.....pls have a error as below

Tunnel session failed: Only paid plans may bind custom subdomains. Failed to bind the custom subdomain 'arvindpattartestfb.ngrok.io' for the account 'arvccccc'. This account is on the 'Free' plan.

Upgrade to a paid plan at: https://dashboard.ngrok.com/billing/plan

ERR_NGROK_313

You need to set up auth token you can find here https://dashboard.ngrok.com/auth. (W̶o̶r̶k̶s̶ ̶w̶i̶t̶h̶ ̶f̶r̶e̶e̶ ̶v̶e̶r̶s̶i̶o̶n̶,̶ ̶n̶o̶ ̶n̶e̶e̶d̶ ̶t̶o̶ ̶p̶a̶y̶ Apparently it's now paid feature, see ngrok pricing).

Then you can use it like this:

ngrok http 80 -subdomain yoursubdomain

Neither localtunnel.me or Serveo are working for me right now so I created a temporary solution that works for some use-cases including mine (react-native local development): using the ngrok npm package one can save the generated ngrok url into a json file, and that file can be read for any other app.

First make sure to install ngrok using npm install ngrok then use this node script:

const ngrok = require('ngrok');
const fs = require('fs').promises;

(async function() {
  const url = await ngrok.connect(3000);
  const api = ngrok.getApi();
  let data = await api.get('api/tunnels');
  data = JSON.parse(data);
  let dict = {'domain': data.tunnels[0].public_url}
  await fs.writeFile("config.json", JSON.stringify(dict));
  console.log("saved " + data.tunnels[0].public_url);
})();

Then from your app you may read it using code similar or equal to:

const backend = require('./config.json').domain;