Gremlin

Gremlin is the graph traversal language of the Apache TinkerPop framework, used to query and mutate property graphs by chaining together a sequence of steps that walk from vertex to edge to vertex. Rather than declaring the shape of the result the way a declarative language does, a Gremlin traversal reads like a functional pipeline that describes exactly how to move through the graph, which makes it expressive for deep, multi-hop path queries.

• Traversal-oriented - Queries are expressed as a chain of steps that navigate the graph, giving fine-grained control over how the walk happens.
• Part of Apache TinkerPop - Gremlin is the language of an open framework, so it is not tied to a single database vendor.
• Broad engine support - Many graph databases and cloud services, including Amazon Neptune and JanusGraph, speak Gremlin.
• Both imperative and declarative styles - It supports step-by-step imperative traversals as well as more declarative pattern matching.

In real API operations Gremlin surfaces wherever a graph database is exposed behind a data API and teams need portable traversal logic across engines. It predates the ISO Graph Query Language (GQL) standard and sits alongside declarative languages like Cypher, so when I evaluate graph-backed services I treat Gremlin support as a signal of TinkerPop compatibility and a hedge against vendor lock-in. Its explicit, step-based traversals also give agents and governance tooling a concrete, auditable description of exactly what data a query touches.