Website -> https://js.cytoscape.org/
Cytoscape could be used on Node.js to perform graph analysis on a web server or in the terminal. Developers moving toward data science in their interest can choose Cytoscape as a good choice, also it has a wonderful contribution guide with documentation.
Website -> https://pdfkit.org/
Very useful PDF generation library for nodes which helps in building and downloading complex PDFs, also it supports text and font embedding, annotations, vector graphics. However, the project has no extensive documentation which makes it harder to contribute to it.
Website -> https://socket.io/
Bi-directional, real-time event-based communication and works on every browser device with equal focus on speed. A basic chat app is an example of two-way communication that the tool provides.
A new message is received by the server then it sends it to the client and notifies them bypassing the need to send a request between the client and the server.
Comes With Useful Features:
Website -> https://strapi.io/
An opensource content management system which a backend only system that provides functions to use with RESTful APIs, the main aim to get and deliver content across all devices structurally.
Comes with plenty of features, includes an inbuilt email system, file upload, and JSON Web Token authentication. The content structure is created via Strapi which is very flexible and lets you create content groups and customizable APIs.
Website -> https://nestjs.com/
Nest is a popular progressive framework for creating efficient and scalable server-side apps. Uses TypeScript for combing functional and object-oriented programming elements & uses Express under the hood. This tool provides true flexibility by letting you use and libraries, thanks to its modular architecture.
Website -> https://date-fns.org/
Website -> https://sheetjs.com/
A Node.js library that allows you to manipulate spreadsheets in Excel and a lot of other things with Excel, for example, exporting workbooks from scratch and converting HTML tables, JSON arrays into xlsx files that are downloadable. Comes with a big community and a well-documented contribution guide.
A very helpful tool to accomplishing speed and security in applications.
Different extensions and plugin support
URL-based routing mechanism uses HTTP methods
Seamless database integration
Thanks Adrian Twarog @adriantwarog for this good and elaborate explanation