As you all are aware, Heroku has recently removed its free tier option which was useful to most devs for their hobby and low traffic apps.
So I've compiled a list of some other Free Hosting services you can consider:
Netlify - Perfect for hosting static sites.
Surge - Another static hosting for your front-end apps.
Render - Perfect Heroku alternative, even costs cheaper than Heroku.
Firebase - App development platform developed by Google, offers a free plan.
Vercel - Works for both frontend and backend.
Stormkit - Another amazing app hosting service, offers enough resources in its free tier.
Glitch - Hosting for frontend and backend apps (recently bought by fastly).
Fly - Hosting for apps and databases, comes with a free tier.
Deno - Free hosting for JavaScript apps.
Nhost - Best alternative to Heroku, apps will sleep after 7 days of inactivity.
Cloudflare Pages - Another popular platform to host static sites.
Fleek - Decent service, comes with a free plan.
AWS Free tier - Only works for the first year, and has a slight learning curve.
These are some of the Free options I found after searching a while on the internet.
If you plan to host you app on free tier, your best approach would be to keep the frontend and backend on separate platforms, that way your app will consume less resources.
I used to host my frontend on Netlify, backend code on Heroku, and database on MongoDb Atlas (Cloud database provider). Now, I'll probably switch from Heroku to Render.
If you know of any other Hosting service then feel free to leave its name in the comment.