This link leads to the machine-readable files that are made available in response to the federal Transparency in Coverage Rule and includes negotiated service rates and out-of-network allowed amounts between health plans and healthcare providers. The machine-readable files are formatted to allow researchers, regulators, and application developers to more easily access and analyze data.
https://www.aetna.com/individuals-families/member-rights-resources/rights/federal-no-surprises-act.html