The ODK ecosystem (build, aggregate, collect) has been in use for our Western Australian flatback turtle conservation program since 2016, now being used by Dept Biodiversity, Conservation and Attractions staff, community programs and Volunteers across the Kimberley and Pilbara regions. We've captured about 12k turtle tracks/nests in ca 2k hours of logged survey work. Data is ingested into a custom data warehouse, comes out via a RESTful API, is analysed in RMarkdown workbooks with common steps documented in a custom R package.

Widgets for notoriously error-prone data like location and date/time as well as replacing free text with dropdown options where possible made the difference for us.

ODK works really well for us, and the fantastic developer community has been greatly supportive addressing feature requests and bugs (quickest fix: Clint Tseng fixed an ODK Build bug reported mid-workshop within 2h). I'd like to see the industry heavyweights like ESRI being that responsive :-)

Cheers to the ODK community!