Katari is a Municipality in Udayapur District in the Koshi province of south-eastern Nepal. It lies by the Tawa river having the bridge of length 123.5m. This was established by merging two existing village development committees i.e. Triveni and Katari on 18 May 2014. At the time of the 1991 Nepal census it had a population of 7230 people living in 1410 individual households. Forty years later, Katari had undergone rapid growth, achieving a population of 59,507 people by the 2021 census. There is a big Government school Triveni secondary school