The National Institute of Standards and Technology (NIST) provides public access to a multitude of compiled chemical and engineering experimental and computational data (https://www.nist.gov/data). Much of the data available from NIST is critically evaluated and extracted from the primary literature; however, there is also unique data available, collected at NIST facilities. For example, NIST obtained the Radionuclide Half-Life Measurements.
To browse a full list of these specialized NIST data resources, we recommend using the NIST Data Gateway: https://srdata.nist.gov/gateway/gateway?dblist=0.
Within the NIST Data Gateway, you will see a full list of data available from NIST, such as the Atomic Spectra Database, Chemistry WebBook, Ionic Liquids Database, and Property Data Summaries for Advanced Materials. There are also useful Mathematics resources like the NIST Digital Library of Mathematical Functions and Guide to Available Mathematical Software. These mathematics resources contain an index of mathematical functions along with an index of software than can compute mathematical functions.
So, check out the NIST Data Gateway, and let us know if you need help navigating any of the NIST resources!