Here's how you can download the Twitter app free for your Mac.
1. Go to the Twitter app preview page.
2. Click the View in Mac App Store button.
3. Click the Free button to download the app.
Here's a description and screenshot of Twitter for Mac:
"Follow your interests: instant updates from your friends, industry experts, favorite celebrities, and what’s happening around the world. Get short bursts of timely information on the official Twitter for Mac app.
Real-time search reveals breaking news, while trending topics show what’s happening around the world.
Features: Find & follow friends, Tweet, Retweet, Favorite, Direct Message privately with your followers, share web pages, real-time search, and view trends."