Grant Transparency Act of 2023 This act establishes transparency requirements for notices of funding opportunity in applications for competitive grants awarded by federal agencies, excluding the Government Accountability Office. Specifically, each notice of funding opportunity issued by an agency for a competitive grant must include a description of any rating system and evaluation and selection criteria the agency uses to assess applications for the grant; a statement of whether the agency uses a weighted scoring method and a description of any such method that it uses for the grant, including the amount by which the agency weighs each criterion; and any other qualitative or quantitative merit-based approach the agency uses to evaluate an application for the grant. Additionally, the Office of Management and Budget must develop relevant data elements to ensure common reporting by each agency with respect to such grant applications.