The Zend Developer Zone points out a post from Gaetano Giunta that compares several JSON libraries that can be used with PHP.

The recent release of php 5.2.0, which includes by default an extension for converting php values from and to the JSON format, is a good occasion for comparing the different existing php libraries which aim to provide the same capabilities.

Included in his "completely fair and balanced comparison" of the libraries were four choices:

• The lib (now part of PHP)
• The JSON lib
• The Zend_Json lib
• The Jsonrpc (and Json) extension

He's created a feature matrix for the four options that includes things like encoding support, failed decoding vs NULL value, and extra features that might be included.

There's loads of other stats presented as well, including bar charts for the speed comparison, code examples, and encoding/decoding test results.