JSCK

JSCK (JSON Schema Compiled checK) is a JSON Schema validator for Node.js that compiles schemas into efficient validation trees for performance. It supports JSON Schema drafts 3 and 4 with some caveats (e.g., no remote refs, no uniqueItems). Current stable version is 0.3.2. It is faster than many alternatives due to compilation, but is no longer actively maintained (last release in 2016). Key differentiators: compiles schema to functions, supports draft 3 and 4, but lacks modern draft 6/7/2019-09 support.