Why Defaultly?

Initially, I created it to solve a personal problem: on macOS, changing the default app for each file extension has to be done manually through Get Info, Open With, Change All, there is no overview and it has to be repeated multiple times.

What does Defaultly do?

• View all 400+ formats in 17 groups (documents, source code, images, audio, video, archives, fonts, 3D/CAD...)
• Change the default app for one extension, multiple extensions, or an entire group in one step
• Quick Setup: move an entire group (e.g., all Office documents) to another app
• Preview before applying, with Undo/Redo and backup/restore associations in JSON format
• Native Mac app: SwiftUI, supports Vietnamese and English
• Private: no network access, no data collection

Note when installing

The app is signed ad-hoc (not with an Apple Developer ID, so it's not notarized), so when you open it for the first time, it will be blocked by Gatekeeper. You just need to go to System Settings, Privacy & Security, Open Anyway to use it normally. This is a normal warning with an app that does not have a Developer ID, it is not malware.