ArangoDB in an hybrid db that can do graphs. Easy to install and use, quite reliable - we use it in production.

https://www.arangodb.com/ (just a happy user)

Also: https://github.com/google/cayley

What about TinkerGraph: http://tinkerpop.apache.org/docs/3.1.0-incubating/#tinkergra...

It is "TinkerGraph is a single machine, in-memory (with optional persistence), non-transactional graph engine that provides both OLTP and OLAP functionality."

Definitely neo4j. If you're on a mac, it's just 'brew install neo4j' and boom you have the free community edition.

Depending on what OP was after, neo4j is hardly a single file, in-process database.

Well, that is not strictly true. You can use neo4j embedded within Java: http://neo4j.com/docs/stable/tutorials-java-embedded.html

You are correct. I was responding more to this:

> easy to install, relatively easy to use, with good reliability, for experimentation

To add on a requirement that poster didn't specify: I've been looking for an embedded single file, in process graph database. Does anyone have a suggestion?

Based on http://www.butleranalytics.com/20-free-and-open-source-graph..., apparently there are BITSY https://bitbucket.org/lambdazen/bitsy/wiki/FAQ.md, BLAZEGRAPH https://www.blazegraph.com/product/embedded/, and others

Do you specifically want a graph database?

Because if not, SpatiaLite's VirtualNetwork module may work for you. Otherwise, neo4j.

Maybe you can try to use a relational DBMS to model the graph data: https://news.ycombinator.com/item?id=10316872

If you're using Python and your graph fits in memory, networkx + any database for persistence.