The duplicate checking rate of paperOK in the market is generally high. So it's not particularly reliable. It's free for the first time. It costs more than 20 yuan after the second time, which is also very cheap. So many people will choose paperok to check the weight. However, compared with the weight difference rate of HowNet, the gap is not generally large. The paperOK of the same article is 15%, but the final usage of HowNet has reached 25%. Among them, HowNet is a domestic brand, and HowNet is the concept of national knowledge infrastructure, which was put forward by the World Bank in 1998, and China HowNet was initiated by Tsinghua University and Tsinghua Tongfang and founded in 1999 in June. Among them, CNKI project is an information construction project aimed at realizing the dissemination, enjoyment and value-added utilization of knowledge resources in the whole society.