Tangle reminds me of mavo.io, although tango is older. I think Mavo aims for more UI heavy stuff (display and editing of structured data) and can read/write a backing store.

I thought I saw something else very similar to tangle years ago, but maybe it was tangle. It'd be interesting to try to do something like tangle from a markdown source.

From the web page, Patera looks similar to coda.io - a wysiwyg editor that tries to expand spreadsheet-like programming to documents.