Ruamelyaml

Ruamelyaml is a data-serialization and configuration language inspired by YAML that aims to combine human readability with stronger structural guarantees. It is designed for use in configuration management, data exchange, and application deployment scenarios where predictable parsing and explicit schemas are valuable.

Key characteristics of ruamelyaml include explicit typing, schema-driven validation, and deterministic parsing. Each value can carry a type annotation, and optional schemas define required fields, default values, and permitted value ranges. This promotes consistency across tools and environments and helps catch configuration errors early in the development or deployment process. The language retains a YAML-like indentation-based structure to preserve readability while adding formal constraints that are not present in plain YAML.

Syntax and tooling focus on cross-language interoperability. Ruamelyaml targets UTF-8 encoding and provides a formal grammar that enables consistent parsing across programming languages. It supports a schema language that can express object shapes, arrays, and primitive types, enabling automatic documentation and tooling support such as validation, schema generation, and editor assistance. Comments are supported to explain configuration decisions, but the primary emphasis is on unambiguous data representation.

History and status: ruamelyaml emerged as an open-source initiative in the early 2020s, with a community-developed specification and multiple language bindings. Implementations exist for popular languages used in backend services and DevOps tooling. The ecosystem emphasizes backward compatibility, extensibility, and interoperability with existing YAML-based workflows, while offering stronger guarantees through schemas and typing.