This paper presents an overview of Amine ; a multi-layer and open-source platform, implemented in Java and dedicated to the development of intelligent systems and agents. Amine is composed of four layers : a) a kernel layer that enables the creation, edition, update and manipulation of multi-lingua ontologies, b) an algebraic layer that offers a set of elementary data types, structured types and various matching-based operations, c) a programming layer that provides three programming paradigms: i) an ontology or memory-based programming paradigm which is concerned by incremental and automatic integration of knowledge in an ontology (or agent memory), ii) a pattern-matching and rule-based programming paradigm, embedded in PROLOG+CG language, and iii) an activation and propagation-based programming paradigm, embedded in SYNERGY language, and d) an agent and multi-agent systems layer that enables the development of agent-based applications.