Neo4j 3.x introduced the concept of user-defined procedures and functions. Those are custom implementations of certain functionality, that can’t be (easily) expressed in Cypher itself. They are implemented in Java and can be easily deployed into your Neo4j instance, and then be called from Cypher directly.
The APOC library consists of many (about 450) procedures and functions to help with many different tasks in areas like data integration, graph algorithms or data conversion.
Starting from Neo4j 4.1.1, there are two available versions of the APOC Library:
- APOC Core
battle hardened procedures and functions that don’t have external dependencies or require configuration. This is also the based of the functionality available in Neo4j AuraDB which lists the available APOC surface in their docs.
- APOC Full
contains everything in APOC core, as well as additional procedures and functions, which is available both in Neo4j Sandbox, the Docker image and Neo4j Desktop, as well as when you self-host the database and add the apoc-full jar.
A list of functions and procedures in APOC Core and APOC Full can be found in Procedures & Functions.