jftl-lang

JFTL — JSON Fold Template Language.

This site is the specification and user guide for JFTL, a declarative JSON-to-JSON transformation engine. It is versioned independently of any particular engine implementation — the Specification section describes what JFTL is, and each implementation (Python reference, Java, Node/JS, Perl) claims compatibility against a specific spec version (e.g. "compatible with jftl-lang 0.4").

• Overview — what JFTL is, core concepts, template structure.
• CLI — using jf-template to run templates from the command line.
• Cookbook — worked examples and recommended patterns.

Use the version selector (top of page) to switch between spec versions.