Package: Swift-Crypto
Reason for nomination: Cryptography is an essential component in various different systems, ranging from password hashing all the way to implementations such as Double-Ratchet and (D)TLS. Its prevalence all around us makes this library very essential on all platforms (CryptoKit on apple OSes).
I've found the library design of extremely high quality in my various implementations with it. While in cryptography, hashes, symmetric keys and many other data forms are represented as [UInt8], the design of this Crypto library makes it so that these types are explicitly defined for their purposed and not confused.
While there has been discussion lately aiming at defining the way forward, I think that stands as a testament to how essential is has already become.