What is the name of the interpreter in the V8 JavaScript engine?

The interpreter in the V8 JavaScript engine is called Ignition. It converts JavaScript functions into V8 bytecode and interprets that bytecode during execution, giving the engine a fast way to start running code before more expensive optimization takes place.

Ignition was introduced during V8’s 2016 development work, with a major goal of reducing memory use. Earlier V8 pipelines relied heavily on Full-codegen and Crankshaft, which produced machine code but could consume substantial memory. Ignition’s compact bytecode made startup and memory behavior more efficient, especially on mobile devices.

Ignition is a register-based interpreter rather than a traditional stack-based interpreter. Its bytecode uses virtual registers and an accumulator to represent intermediate values. Frequently executed code can then move through V8’s tiered optimization pipeline: Sparkplug and Maglev provide faster compiled tiers, while TurboFan targets highly optimized machine code.

A common mix-up is choosing TurboFan because it is strongly associated with V8 performance. TurboFan is an optimizing compiler, not the interpreter. Crankshaft and Full-codegen are older V8 components that no longer serve as the standard answer to this question.