htDig2

Beagle   (Compare Project)

Mostly written in C#

License: mit

Whoosh Python Search Library   (Compare Project)

License: bsd_2clause_ish

TouchGraph   (Compare Project)

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License: Closed_Licence, Proprietary

OpenSearchServer   (Compare Project)

License: gpl3

Tracker   (Compare Project)

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License: gpl

Wikitty   (Compare Project)

Mostly written in Java

License: lgpl

Sphinx Search   (Compare Project)

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eZ Find   (Compare Project)

Mostly written in TypeScript

License: gpl

Namazu   (Compare Project)

Mostly written in Perl

License: gpl

CSearch   (Compare Project)

License: gpl3_or_later