Like you say, there are a few apps that claim to increase your internet speed, but they tend to be placebos at best. There are also download accelerators that use your mobile data and WiFi simultaneously to increase individual file download speed but they won't affect your overall internet speed. There's no guarantee way to improve it, but if your phone's rooted and has decent developer support you can try a custom kernel and use a different TCP algorithm (Westwood is the best, generally). Basically it schedules your data packet downloads so your bandwidth is used effectively.
— modified on Aug 4, 2015, 4:11:42 PM