# Polyglot API A polyglot API presents aligned capabilities in multiple programming languages. The important invariant is behavioral parity—not merely similar names. X's intended JavaScript, Node, PHP, Python, and Perl surfaces become a polyglot API when each implementation shares canonical names, input rules, normalized outputs, errors, and fixtures. Related: [[wiki/Cross-Runtime Capability Parity|Cross-Runtime Capability Parity]], [[wiki/Portable Contract|Portable Contract]], [[wiki/Conformance Testing|Conformance Testing]].