One popular option is Hootsuite. It allows you to schedule tweets, monitor mentions and keywords, and manage multiple accounts in one place.
Another useful tool is TweetDeck, which is actually owned by Twitter. It provides real-time monitoring of your Twitter feed, allows you to schedule tweets, and offers advanced search options.
Buffer is another tool worth considering. It allows you to schedule tweets, track engagement metrics, and even suggests optimal posting times based on your audience’s activity.