Umigon is a free, web-based and open-source tool for sentiment analysis of tweets. From a person's Twitter handle, Umigon retrieves that account's tweets and processes it for sentiment with accounting for factual statements (ex: "I hate war" will be classified has negative, and "war in Syria" will be classified as neutral). Tweets can also be pasted manually in the entry box provided. Beyond sentiment analysis, Umigon can identify characteristics such as whether the tweet contains a question, whether it contains possible promotional/commercial subject matter, or temporal indicators based on tense. Users are encouraged to report inaccurately identified sentiments via the button provided next to each tweet. Results can be exported in Excel or CSV format for futher analysis.