Assembler framework is a final missing piece of the reverse engineering (RE) community. This talk introduces a new framework named Keystone, which fills this gap and offers unrivalled features: Multi-architecture: Arm, Arm64, Hexagon, Mips, PowerPC, Sparc, SystemZ & X86 (16/32/64 bits) Multi-platform with native compiled for Windows, Linux, Mac OS X, *BSD, Solars, etc Clean/simple/lightweight/intuitive architecture-neutral API. Implemented in C/C++ languages, with bindings for Python available. Thread-safe by design. Open source. We are going to present the motivation, design & implementation of Keystone. The focus will be on technical decisions we made, and the challenges we had to overcome to realise the ideas behind our engine. We expect Keystone will turn a new page and open ways for many next generation RE tools in the future. Some cool tools built on top of Keystone will be shown to demonstrate its power.