Yep, there's no way around mapping – the data has to get mapped somehow. The 835/837 are a bear. You can save some time if someone has built a mapping template already – say, from a transaction type in Oracle to the 837 – but if it's a custom system you're mapping to/from (like a homegrown API), it's impossible for a template to exist...it has to be done from scratch.

We've found that many of the fields end up being single-item enums, so those can be hardcoded (i.e. no mapping required). Guides (https://www.stedi.com/products/guides) generates JSON Schema for you, and Mappings (https://www.stedi.com/products/mappings) automatically populates any single-item enum. Both are free to configure in the UI.