The "Endangered Species Transparency and Reasonableness Act of 2025" proposes significant amendments to the Endangered Species Act of 1973, primarily focusing on increasing transparency and accountability. It mandates that the Secretary make publicly available on the internet the best scientific and commercial data available that forms the basis for all species listing regulations, with specific exceptions for state-protected personal information and classified Department of Defense data. Additionally, the bill requires federal agencies to provide all underlying data to affected States before making a determination and explicitly defines "best scientific and commercial data available" to include information submitted by State, Tribal, and county governments . This legislation also introduces new requirements for the disclosure of federal expenditures related to the Endangered Species Act. It directs the Secretary of the Interior, in consultation with the Secretary of Commerce, to submit an annual report to Congress and maintain a publicly accessible, searchable online database detailing federal spending on "covered suits." This includes comprehensive information such as case names, claims, involved agencies, funds expended, and attorneys' fees awarded, even if subject to non-disclosure agreements. Finally, the bill amends the criteria for awarding litigation costs to prevailing parties in ESA cases, aligning them with existing federal law under the Equal Access to Justice Act and the Administrative Procedure Act.