Top 20 NuGet indexing Packages

Index modular/rendered content added to a page via Sitecore Experience Editor. Determine which renderings should be indexed based on patch config. All logic broken out into Sitecore pipelines to provide customization support.
Provides a simple API to use Lucene.NET with objects without having previous knowledge of indexing
Word/document similarity based on random indexing.
Allows the customization of where indexes start in C#. Not only can you force Roslyn to interpret items[1] as items[0], but also items[-42] and items[1_000_000] if you want! The sky (and common sense) are the only limits!
Scalability stuff.
Tiny Fast Json Parser Support Multiple Indexing, Json Object And Json Array.
Json Transformer
Package description