Looking for open source solutions to build a custom niche CRM SaaS

Hello everyone, I have been working on a construction/ flooring estimation app and have already made a few prototypes to validate the idea. I am looking to add some CRM functionality to add some value in it. Essentially I want to customize the crm with flooring estimation needs and integrate it with my current app.

I have looked into a few options like go high level and suitedash. But they are not open source and I can’t customize them with my needs.

Saw an open source solution in code canyon called perfex, not sure if thats a good idea.

Here is what I am looking for:

It’s a SaaS, so users sign up and use it as a CRM for their projects. So basically users should be able to do the followings: – Client Portal – Payment and Invoice – Estimation and Report Generation – Project Management – Quickbook Integration – payment method – Marketing

Do you think it’s practically possible? I could certainly do some hack with WordPress, but not a big fan of it.