vallid

Vallid is a neologism used in discussions of software engineering to describe a holistic approach to value validation across system boundaries. It is not a formal standard, but rather a term used to frame practices that strive for end-to-end correctness and data integrity from input through processing to output.

Origin and usage: The word appears in online glossaries and practitioner blogs in the early 2020s. It derives from a stylized spelling of "validate" and is sometimes expanded as "validate all values" or "value validation across layers." It is usually described as an approach rather than a single tool or method.

Core principles: Vallid emphasizes end-to-end invariants, traceability of validation decisions, and a layered mix of static analysis, runtime checks, and monitoring. Proponents argue for harmonizing validation criteria across components, data models, and interfaces, so all values entering and leaving a system remain within expected bounds.

Applications and scope: The concept is discussed in contexts such as API design, data pipelines, microservices architectures, and safety-critical software. It supports both automated testing regimes and runtime verification, aiming to reduce defect propagation and improve observability of data quality.

Limitations and reception: Because vallid lacks a formal specification, interpretations vary and implementations can introduce overhead if not carefully scoped. Critics caution against conflating a buzzword with rigorous methodology; supporters see vallid as a helpful mental model for cross-cutting validation concerns.

See also: Data validation, Formal verification, End-to-end testing.