Endangered Species Transparency and Reasonableness Act of 2025 This bill modifies requirements concerning determinations on whether a species is a threatened or endangered species under the Endangered Species Act of 1973 (ESA), caps attorney's fees to prevailing parties in ESA citizen suits, and makes related requirements. The U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) must publish online, subject to privacy or administrative limitations, the best scientific and commercial data available that are the basis for each determination. The bill states that the term best scientific and commercial data available includes all data submitted by a state, tribal, or county government. Thus, such data is automatically deemed to be the best scientific and commercial data available. Before making a determination on whether a species is an endangered or threatened species, the FWS and NMFS must provide affected states with all of the data that is the basis of the determination. The Department of the Interior must also publish and maintain an online searchable database that discloses federal expenditures related to litigation under the ESA.