Apps to Sync between devices

ActivityWatch is a free and open-source, privacy-focused time-tracking application that automatically monitors how you spend time on your devices, offering detailed insights into your digital activities with local storage and offline functionality.

Elephant is a portable, privacy-focused note-taking application featuring a classic, intuitive interface. It supports robust note organization, rich text formatting, markdown, and offline access. With capabilities like image insertion and secure cloud synchronization, Elephant is designed for users needing a reliable and versatile digital notebook.

ThinkComposer is a highly flexible visual modeling tool designed for users to create rich, structured diagrams based on their specific domain knowledge. It facilitates the organization and visualization of complex information through various diagram types and hierarchical structures, enabling deep understanding and effective communication of ideas.

CmisSync is a robust desktop application that synchronizes files between your local computer and any CMIS-compliant Enterprise Content Management (ECM) system. It mirrors your ECM content locally, allowing offline access and seamless collaboration.

MyTetra is a versatile, cross-platform information manager designed for collecting, organizing, and managing various types of data. It excels as a portable note-taking application, personal information manager, and notebook, offering a robust outliner and rich text editing capabilities.

Turtl is a secure and private note-taking, bookmarking, and document storage application. It utilizes strong client-side encryption to ensure that only you and authorized collaborators can access your sensitive information, making it ideal for managing confidential projects and data.

Syncany was a discontinued open-source file synchronization and backup application designed with a strong emphasis on security and privacy. It offered client-side encryption and allowed users to back up and sync data to various cloud storage providers or even their own servers.

OpenNote is a free and open-source web-based note-taking application designed as an alternative to commercial offerings like OneNote and Evernote. It focuses on providing a lightweight yet feature-rich environment for organizing your thoughts and information.

FBReader is a versatile and free ebook reader application supporting multiple formats including ePub, Kindle azw3, and fb2. It offers a customizable reading experience across different platforms with features like library management, synchronization, and text-to-speech.

Leanote is a versatile self-hosted note-taking application that blends rich text editing with Markdown support. It offers seamless synchronization across multiple devices and features built-in blog publishing capabilities, making it a powerful tool for both personal information management and content creation.

Simplenote is a minimalist note-taking application designed for speed and efficiency. It provides a clean interface across multiple platforms, focusing on text-based notes with robust synchronization and versioning capabilities. Ideal for capturing ideas quickly and accessing them anywhere.

Financisto is a feature-rich, open-source personal finance manager application for Android devices. Though discontinued, it offers robust tools for tracking income, expenses, accounts, and budgets with offline capabilities and data privacy.