Set default applications in Mac OS X.


RCDefaultApp is a free utility that CreativeTechs has started adding to our recommended Mac OS X installs. It adds a special preference pane that allows you to quickly change the default application for many common situations:

  • Open all your .pdf files in Acrobat instead of Preview.
  • Pick a different default mail client or web browser.
  • Control what opens when digital cameras or webcams are plugged in.
  • Close security holes with how certain weblinks are handled.

Of course you can change these settings other ways. But RCDefaultApp makes it much easier by putting the most requested controls into one location — a new “Default Apps” option at the bottom of your Mac OS X System Preferences.

With this plethora of options it can be a little overwhelming for the casual user. We outline a few of the most common examples below.

Open the Default App preference pane.

Once RCDefaultApp is installed, simply go to Mac OS X’s system preferences (found under the Apple menu) and click on the “Default App” at the bottom.


Control which applications open certain files.

Want all your PDF files opened in Acrobat Reader instead of Preview? Want all PDF, JPG, or TIF files to open in Photoshop?


Choose the Extensions tab and scroll down through the list of file extensions to the ones you are interested in. Choose your default application from the pop-up menu.

Tip: Look for similarly named file extensions — especially uppercase vs lowercase. To change your PDF setting for example, you may have to set “PDF” and “pdf” separately.

Pick a different default mail client or web browser.

Do you want to use Entourage as your default email program? Maybe you prefer Firefox over Safari. These settings are grouped together under the Internet tab.


Close security holes with how certain weblinks are handled.

Warning: overly technical content below. Feel free to skip.

Certain of Mac OS X’s default handlers for custom URI protocols (weblinks) expose exploitable security holes. One such vulnerability is detailed far too thoroughly at the special Month of Apple Bugs website.

These types of vulnerabilities can be addressed by choosing the URI tab and setting any vulnerable URI entries to “disabled.”


For best security, we’d recommend disabling the following URI:

  • rtsp (vulnerability described here)

For additional details we’d refer readers to the article Disabling Unsafe URI Handlers With RCDefaultApp at Daring Fireball.

As our security-conscious consultant Jordan Bojar said when lobbying for the addition of these security details, “Mostly, it’s just cool to set all your PDFs to open in Acrobat.”

Source: This tip inspired by research and testing by CreativeTechs consultant Jordan Bojar.


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  3. n. p. says

    I have the same problem as Sine. Every time I have to restart, I loose all associations. I don’t know if it is a bug in this program of something that Mac OS does. I think it’s Mac OS. It is very frustrating.

  4. LL says

    Lovely!!! This tiny app is just great! 😉 thx to HHH too, that shortcut is simple and useful

  5. Sine says

    This is a great recommendation – but I can’t get my preferences to stick. For example if I want .as files to open in Textmate,I can make that choice; but if I shut down, the next time I open .as has defaulted back to – damn it – dreamweaver! Any clue how to make my choices stick…

  6. HHH says

    have another way to set default running application without using 3rd application.
    Right on file want to change default app -> get Info -> “Open with..”

  7. someone_with_mac says

    Excellent thing! I’ve just started working on my first Mac and this software helped me to organize the way of file opening, without time wasting.


  8. pete says

    excellent app, been using macs for years, new apps downloaded from the internet have a default app setting and this baby just tells it to go take a hike! excellent stuff, award winning in my eyes and hopefully apple will see this and add it to their OS in the future

  9. Willozap says

    Thanks! Have been battling default apps for ages, and this app has solved my problem!
    (Though to confess, I went the other way, from default Acrobat to Preview – speed is my goal).

  10. says

    This is a great app. I am a graphic designer and I work alot with images and Preview wants to open everything. This helps getting images to open everytime in Photoshop.

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