FraudSentinel provides a REST-API and monitoring pixel that can be used for small blog projects, monitoring advertisement traffic, and detecting frauds in e-commerce web sites. The API helps identify fraudulent transactions by providing a fraud score based on the customer's IP address, which can help prevent chargebacks. In addition, the API helps measure the quality of traffic sources, and in most cases, the place you get the traffic from will reimburse you for fraudulent traffic. FraudSentinel uses both on-site and live databases with millions of IPs cached on their servers and billions of IPs on live databases worldwide. Their Fraud Monitoring Pixel is free to use, and implementing their REST-API takes only a few lines of code, making it easy for any site owner to measure their exposure and prevent fraud.