JSON Parsers
multi_json Recommended
A common interface to multiple JSON libraries, including Oj, Yajl, the JSON gem (with C-extensions), the pure-Ruby JSON gem, NSJSONSerialization, gson.rb, JrJackson, and OkJson.
json
This is a JSON implementation as a Ruby extension in C.
yajl-ruby
Ruby C bindings to the excellent Yajl JSON stream-based parser library.