Open Source Software for JavaScript
RxDB
RxDB is short for Reactive Database and is a NoSQL-database for JavaScript Applications like Websites, hybrid Apps, Electron-Apps, Progressive Web Apps and NodeJs. Reactive means that you can not only query the current state, but subscribe to all state changes like the result of a query or even a single field of a document. This is great for UI-based realtime applications in way that makes it easy to develop and also has great performance benefits. To replicate data between your clients and server, RxDB provides modules for realtime replication with any CouchDB compliant endpoint and also with custom GraphQL endpoints.
Vapid
Vapid is a free and open-source CMS that takes the best of static site builders and introduces the ability to have a dashboard with almost no extra effort. As static site builders like Jekyll and Middleman offer a modern development environment but are for the most part difficult to share with folks who would like a dashboard to edit content. Vapid is designed to be an intentionally simple content management system built on the idea that you can create a custom dashboard without ever leaving the HTML.
PouchDB
PouchDB is a free and open-source JavaScript database inspired by Apache CouchDB. The database is designed from the ground-up to run well within modern web browsers. With PouchDB you can create web applications that works as well offline as they do online. PouchDB achives this by storing data locally, then synchronize it with CouchDB and compatible servers when the user get internet access once again. This is especially useful for applications facing countries and regions with lower quality internet connections or unstable infrastructure.
WatermelonDB
WatermelonDB is a free and open-source database optimized for building complex applications in React and React Native. The goal of WatermelonDB is to provide real-world performance for apps that can scale from hundreds to tens of thousands of records and while remaining performant. Loading a full database into JavaScript can be expensive, WatermelonDB fixes this by being lazy as a default, and only loads data upon request.
ownCloud
With ownCloud, organizations can collaborate and be more production on their own secure enterprise file sharing (EFSS) platform. The ownCloud platform is self-hosted and allow for secure file sharing within an organization. The platform can be hosted on premise or on a cloud instance, controlled by the organization. The software is written in PHP and Javascript and is fully open source, released under the AGPLv3 license. ownCloud can run on most server hardware and operating systems, and the client for accessing ownCloud is available for Android, iOS, macOS, Linux and Windows.
SurrealDB
SurrealDB is an innovative cloud database, suitable for serverless applications, JAMstack applications, single-page applications, and traditional applications.It reduces the development time of modern applications by simplifying your database and API stack, removing the need for most server-side components. Allowing you to build secure, performant apps quicker and cheaper. For a hassle-free setup, get started with SurrealDB Cloud in one-click.
Publii
Publii is a free and open-source headless CMS designed for speed and ease-of-use. With Publii, you can build beautiful modern sites that will run fast in browser thanks to Google's AMP technology. What make Publii unique is that the content management is done via a desktop-based client that works for MacOS, Linux and Windows.
TaffyDB
TaffyDB is a free and open source, Pure-JavaScript database abstraction that stores data in JSON format. TaffyDB provides INSERT, DELETE, GET (SELECT) and JOIN methods to execure the data similar to that of traditional relational SQL databases. TaffyDB allows you to quickly setup an in-memory database that can be used in the same fashion as an SQLite database would, without configuration and a database server running.
Meteor
With Meteor you can build web, mobile and desktop apps quickly. Meteor is a free and open-source JavaScript framework that is designed to provide developers with the necessities to build applications by writing less code. Over half a million developers around the globe has chosen Meteor as their go-to framework for building scalable JavaScript applications.