JSON is a messy format, you'll always have to know your requirements well to be able to pick a fitting parser for it.
Are you going to parse a simple, small key-value-structure? Pretty much any library will solve it for you or you could invent your own simple parser.
If you need to stream gigabytes of complicated JSON and do sophisticated transformations back into JSON or something like that, then you'll have to evaluate several libraries and have a look at how they translate into CL datatypes. Some might reduce a combination of false, null, the empty list to NIL, which could lead to information loss and surprises.
Are you going to parse a simple, small key-value-structure? Pretty much any library will solve it for you or you could invent your own simple parser.
If you need to stream gigabytes of complicated JSON and do sophisticated transformations back into JSON or something like that, then you'll have to evaluate several libraries and have a look at how they translate into CL datatypes. Some might reduce a combination of false, null, the empty list to NIL, which could lead to information loss and surprises.