This paper presents a browser-based software tool, Paperfetcher, to automate the handsearch portion of systematic reviews. Paperfetcher has two parts: an extensible back-end framework written in Python, which does all the heavy lifting, and a set of easy-to-use front-end apps for researchers. The front-end apps can be run online, with no setup, on a cloud platform. Privacy-conscious users can run the app on their computers after a few steps of installation, and advanced users can modify the source code and extend the back-end interface for their own specific needs. Paperfetcher's website has user guidelines and a step-by-step setup video to coach researchers to use the software. With Paperfetcher's assistance, researchers can retrieve articles from designated journals and a given timeframe with just a few clicks. Researchers can also restrict their search to papers matching a set of keywords. In addition, Paperfetcher automates snowball-search, which retrieves all references from selected articles. Paperfetcher helps save a considerable amount of time and energy in the literature search portion of systematic reviews.