There is a class of excellent open source tools that can replace commercial software for web development, document processing, data management, and image hosting. They are all open source, self-hostable, and integrable with personal knowledge systems like Obsidian.
For web development, GrapesJS is an excellent visual drag-and-drop tool. It is entirely front-end based, requires no back-end service, and automatically generates HTML, CSS, and JS code from drag-and-drop components. Suitable for building personal websites or landing pages.
For document processing, Markdown combined with Pandoc can replace Word and most office software. Markdown core philosophy is separation of content and style. Pandoc provides format conversion capabilities. You can export Markdown to PDF, Word, HTML, and virtually every other major format.
For databases, SQLite is the simplest and most powerful embedded database. No installation or configuration required. It stores data as a file, sufficient for the data needs of most small to medium-sized applications. Combined with a tool like Datasette, you can query the database as if browsing a website.
For image hosting, MinIO is compatible with the Amazon S3 protocol. You can deploy a high-performance object storage service on your own server. Combined with image management tools like PicGo, you can achieve local management andfast uploading of images.
The core criterion for choosing open source tools is not that they are free. It is that they arecontrollable. Commercial tools can change their pricing model, adjust functionality, or cease service at any time. Once an open source tool is deployed, you have complete control over it.