Title: How to Efficiently Migrate Data from MSSQL to MongoDB?

I'm working on migrating data from an existing MSSQL database to MongoDB for a new application that requires flexible schema design and scalability. The MSSQL database contains complex relationships and large datasets.

I would like to know:

The best tools or libraries for this migration (e.g., Node.js scripts, ETL tools, or other migration software).
Recommended strategies for mapping SQL schema (tables, relations) to MongoDB's document-based schema.
Tips for optimizing performance during the migration process, especially when dealing with large datasets.
Potential challenges I might encounter and how to address them.
I am using Node.js with TypeScript for my application, so solutions or scripts in this ecosystem would be particularly helpful.

Thanks in advance for any guidance or examples!