level.js an implementation of the leveldown API on top of IndexedDB (which is in turn implemented on top of LevelDB, which brings this whole shebang full circle)
LevelDOWN was extracted from LevelUP and now serves as a stand-alone binding for LevelDB.
However indexDb has a 50mb total file size restriction. This might seem ok at first, but some transcriptions can reach 5mb in size in their json representation. So this would not scale if you add n number of transcription.