Open With — change default apps for file types and URL schemes on macOS

Open With is a free, lightweight, native macOS app for viewing and changing default application associations: which app opens .pdf, .md, .json, .html and every other file extension, UTI (Uniform Type Identifier), and URL scheme (http, mailto, …) on your Mac. It can also act as an "Open With" chooser: set it as the default for a file type, and it asks which app to use every time you open a file of that type.

Written in plain Objective-C and AppKit. No Electron, no dependencies, no background daemons. Requires macOS 12 Monterey or later and runs natively on Apple Silicon and Intel.

Why

macOS has no built-in screen that shows all file associations. The Finder's Get Info → Open with → Change All… works on one extension at a time and does not cover URL schemes. Command-line tools such as duti need you to know bundle IDs and UTIs. Open With lists everything in one window, lets you search it, and changes defaults in bulk with a couple of clicks.

The app was inspired by duti. It started from two everyday problems: switching every file type from one code editor to another (for example, between Antigravity and Visual Studio Code), and making .pdf open in Preview after Finder's Open With would not keep the change.

Features

• Every association in one table. Each extension and URL scheme claimed by any installed app, with its UTI, the number of apps that claim it, and the current default app.
• Per-app view. Select an app in the sidebar to see every document type, extension, UTI, and URL scheme it declares, its role (Editor/Viewer) and handler rank (Owner/Default/Alternate), and whether it is currently the default.
• Search by app name or extension. Type .pdf to find every app that can open PDFs, including apps that claim a parent UTI such as public.image.
• Bulk reassignment. Select many rows and press Return to assign them all to one app, or ⌘D to make the selected app the default for its own types. In All Extensions, rows can be reassigned together only when they share the same current default, so a stray ⌘A can't hand every type to one app. System-critical types (applications, Unix executables, folders, volumes, public.data, the file scheme) are shown greyed out and are never reassigned.
• Change URL scheme handlers. Search http, mailto: or any custom scheme:// to set the default browser, mail client, or other URL handler.
• "Open With" picker for files. Make Open With the default for a file type and you get a quick, filterable chooser every time you open such a file. It remembers your last choice per extension and includes an Always open with this app checkbox.
• Generic handlers hidden by default. Apps that claim "any file" (public.data) are filtered out unless you press ⌘G.
• Copy to clipboard. Use ⌘C on any selection.

Install

Download the latest OpenWith-x.y.zip from Releases, unzip it, and move Open With.app to /Applications or ~/Applications. It is a universal build that runs on both Apple Silicon and Intel Macs.

The app is ad-hoc signed and not notarized, so macOS blocks the first launch. Allow it in System Settings → Privacy & Security → Open Anyway, or run:

xattr -dr com.apple.quarantine "/Applications/Open With.app"

Or build from source (needs the Xcode Command Line Tools: xcode-select --install):

git clone https://github.com/hza/openwith.git
cd openwith
make install     # builds and copies "Open With.app" to ~/Applications

make install also registers the app with LaunchServices, so it appears straight away in Finder's Open With menu.

Usage

1. Launch Open With. With All Apps selected, the table shows every known extension and its current default app.
2. Search with ⌘F, by app name (Preview), extension (.md), or URL scheme (mailto, https://).
3. Select one or more rows and press Return (Assign to…), choose an app, and click Assign.
4. Or pick an app in the sidebar, select its rows, and press ⌘D to make it the default for them.

Use it as an "Open With" chooser

Assign a file type (for example .md) to Open With itself. Opening a Markdown file then shows the chooser, so you can pick the editor or viewer you want each time. Tick Always open .md files with this app to make that choice permanent. Manage Associations… opens the main window.

Keyboard shortcuts

Shortcut	Action
⌘F	Search apps, extensions, or URL schemes
Return	Assign selected rows to another app
⌘D	Make the selected app the default for the selected rows
⌘G	Show or hide generic handlers in the app picker
⌘A	Select all rows
⌘C	Copy the selected rows
⌘R	Rescan installed applications

How it works

Open With scans /Applications, /System/Applications, /System/Library/CoreServices and ~/Applications, and reads each app's Info.plist (CFBundleDocumentTypes, LSItemContentTypes, CFBundleTypeExtensions, CFBundleURLTypes). It resolves types with UniformTypeIdentifiers and reads and writes defaults through the public NSWorkspace APIs (URLForApplicationToOpenContentType:, setDefaultApplicationAtURL:toOpenContentType: and related calls). It uses no private APIs and does not edit the LaunchServices database by hand.

Building

Command	Description
make	Build and ad-hoc sign build/Open With.app
make run	Build and launch from build/
make install	Install to ~/Applications and register with LaunchServices
make open	Quit, reinstall, and relaunch
make uninstall	Remove the app and its preferences
make clean	Remove build/
make help	List all targets

FAQ

How do I change the default app for a file type on a Mac? Open Open With, search for the extension (for example .pdf), select the row, press Return, choose the app, and click Assign.

How do I change the default app for every extension an app supports? Select the app in the sidebar, click any of its rows and press ⌘A to select them all, and press ⌘D.

How do I move all file associations from one app to another, for example from Antigravity to VS Code? Select the old app (Antigravity) in the sidebar, click any of its rows and press ⌘A to select them all, press Return, choose the new app (Visual Studio Code), and click Assign. Every extension and UTI the old app claimed now opens in the new one.

Or go the other way: select the new app (Visual Studio Code) in the sidebar, click any of its rows, press ⌘A, then ⌘D. That makes it the default for every type it declares, including types the old app never claimed.

Why do PDFs keep opening in Preview (or Acrobat) after "Get Info → Open with → Change All…"? How do I change the default PDF viewer on a Mac? It's a long-standing macOS problem. Finder's Change All… sometimes doesn't take effect, or the default app for PDFs reverts later. People report it with Preview, Adobe Acrobat, Acrobat Reader and other PDF apps. To fix it, search for .pdf in Open With, select the row, press Return, choose your PDF app (Preview, Acrobat, PDF Expert, …), and click Assign. Open With sets the default handler for the PDF content type (com.adobe.pdf) directly through LaunchServices. That is the same change as duti -s <bundle-id> com.adobe.pdf all, and it often works when the Finder setting won't stick. The same steps work for any other file type whose default app keeps resetting.

How do I change the default browser or mail app? Search for http (or mailto), select the URL scheme rows (http:// and https:// for a browser), press Return, choose the app, and click Assign. macOS may ask you to confirm the change.

Is it a replacement for duti or RCDefaultApp? Yes, it does the same job with a graphical interface: listing and changing file-extension, UTI, and URL-scheme handlers.

Does it need special permissions or run in the background? No. It only uses public NSWorkspace APIs and runs only while it is open.

License

MIT © 2026 Henady Zakalusky