I am working on facebook messenger.
Facebook app only accept one url for webhook but ngrock is generating new URL every time. Now I am unable to test my app because of webhook URL changed.
Answer
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!