https://fielddb.github.io/

An offline/online field database which adapts to its user's terminology and I-Language.

It is fundamentally an app written in 100% Javascript which runs entirely client side, backed by a NoSQL database (we are currently using CouchDB and its offline browser wrapper PouchDB alpha). It has a number of webservices which it connects to in order to allow users to perform tasks which require the internet/cloud (ie, syncing data between devices and users, sharing data publicly, running CPU intensive processes to analyze/extract/search audio/video/text). While the app was designed for "field linguists" it can be used by anyone collecting text/audio/video data or collecting highly structured data where the fields on each data point require encryption or customization from user to user, and where the schema of the data is expected to evolve over the course of data collection while in the "field."
https://www.lingsync.org/