We present ClaimPortal, a web-based platform for monitoring, searching, checking, and analyzing English factual claims on Twitter. We explain the architecture of ClaimPortal, its components and functions, and the user interface. While the last several years have witnessed a substantial growth in interests and efforts in the area of computational factchecking, ClaimPortal is a novel infrastructure in that fact-checkers have largely skipped factual claims in tweets. It can be a highly powerful tool to both general web users and factcheckers. It will also be an educational resource in helping cultivate a society that is less susceptible to falsehoods. While it currently focuses on politics-related tweets, it will be extended to include more general factual claims.