The latest module versions of Drupal and Typo3 now both use the solarium library.
I think solarium is the most used PHP library for Solr and it is the most active project.

But as one of the maintainers of the Drupal integration and the solarium library itself, my opinion might not be totally objective ;-)

Markus Kalkbrenner
Dipl.-Ing. (FH) techn. Informatik

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