Firebase vs MongoDB

MongoDB is a more robust document database known for high performance and best-in-class security and has several advantages over Firebase.
MongoDB can be operated on-premise or in the cloud (using MongoDB Atlas, or self-managed cloud MongoDB), It was developed by MongoDB Inc. in 2009. MongoDB provides a more secure
Firebase is a Backend-as-a-Service (Baas). It provides developers with a variety of tools and services to help them develop quality apps, grows their user base, and earn profit. It is built on Google's infrastructure. Firebase is categorized as a NoSQL database program, which stores data in JSON-like documents.
Firebase is purely a cloud database service.
Firebase was developed by Google in 2012. It is not much secure compared to MongoDB
Both Firebase and MongoDB are modern post-relational databases that allow for flexibility and speed to market, while Firebase is more popular for smaller applications, and MongoDB is popular for big data and high-performance use cases.

SQL vs MongoDB

SQL databases are used to store structured data while NoSQL databases like MongoDB are used to save unstructured data.
MongoDB is used to save unstructured data in JSON format. all individual records are stored as documents which are collections of fields with a dynamic schema. Here, each collection need not have the same set of fields which makes it more flexible than RDBMS.
MongoDB does not support advanced analytics and joins like SQL databases support.
In SQL Databases, records are stored in rows within a table which limits dynamic classification and storage of hierarchical data. However, SQL Relational data can be matched using common characteristics simplistically which can be beneficial depending upon your use case.
MongoDB offers faster query processing but with an increased load and system requirements. Without knowing the purpose of use, it is not possible to classify SQL Databases or NoSQL Databases like MongoDB as better or worse than the other.
There are various factors that drive the MongoDB vs SQL decision.
MongoDB isn't meant to replace SQL. It simply fulfills different needs, and MongoDB and an RDBMS can be used in conjunction
MongoDB does not support advanced analytics and joins like SQL databases support.
MongoDB is more fast and scalable in comparison to the SQL server. MongoDB doesn't support JOIN and Global transactions but the SQL server supports it. MongoDB supports a big amount of data but the MS SQL server doesn't

Firebase uses NoSQL; MySQL uses SQL. Firebase is horizontally scalable; MySQL is vertically scalable.
Firebase uses key-value, wide-column, graph, or document stores; MySQL is table-based.
Firebase has dynamic schemas to facilitate unstructured data; MySQL has predefined schemas