CogDB
A persistent, embedded graph database for Python that stores data as a triple store and is queried through a chainable Python query language called Torque, with no server to run.
CogDB is a graph database that runs inside a Python process rather than as a separate server, installed with pip and imported directly into an application, notebook, or script. It models data as triples of a source node, an edge label, and a destination node, so a fact such as a key-value pair or a relationship such as one node following another are both expressed the same way.
Its query language, Torque, is a fluent, chainable API written in ordinary Python rather than a separate query string, supporting operations such as scanning vertices or edges, following outgoing edges from a starting node, and filtering by a property value. Triples and whole JSON documents can be inserted, updated, or replaced, and it works well in interactive environments such as IPython and Jupyter.
It is written in Python and released under the MIT license.