Collaborative map module integration (leaflet) in a Webapp (MEAN stack

We are looking for a Leaflet expert to create a collaborative map module for our existing webapp. Main features are : loading of a base map (openstreetmap), download of picture overlay with basic georeferencing, adding object on the map (line, polygons,...), related function to save in the backend (mongoDB), implementation of socket.io for these features.

Senior full-stack web developer MEAN :
Experience in implementing Leaflet.js (this is a must have)
Angular/MongoDB/Node, solid Back-end skills as most of the work is concerning backend tasks.
5 year XP min
Usage of Git & Heroku for deployment
Knowledge of web sockets & PWA development
Valuable technical skills : knowledge of the services & library we use : Auth0, tabulator.js, socket.io

English or French speaking (for video calls & chat)
No agency or people working under a company. The person who applies should be the one doing the job.

We will not answer messages from profiles not matching the above conditions.

The freelancer will work on making evolutions on an existing code. Ability to read code written by others and understand its logic is important.