I built an API that adds auth, OAuth and billing to apps

I’ve been building web apps for a while and one thing kept bothering me: almost every project needs authentication, OAuth providers and some kind of billing.

But implementing it properly takes a lot of time.

Setting up things like:

OAuth providers

sessions and tokens

user management

billing logic

often took longer than building the actual product.

So I started building a small API that handles these parts.

The goal was to make it extremely simple to integrate. For example, social login can look like this:

npm install syntro-js-client

const { Syntro } = require('syntro');

const syntro = new Syntro(process.env.SYNTRO_API_KEY);

const { redirectUrl } = await syntro.socialLogin('google');

Then the rest of the flow is handled automatically.

Right now it supports things like authentication, OAuth providers, user management and billing integrations.

I mainly built it because I kept rewriting the same auth + billing logic in every project.

Curious what other developers think about this approach — would you rather build these systems yourself or use a service?

If anyone wants to check it out: https://syntro.fun

Feedback would be really appreciated.