Ark.jl is an archetype-based Entity Component System (ECS) for Julia. It is a port of the Go ECS Ark.

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Features   •   Why ECS?   •   Installation   •   Usage

• Designed for performance and highly optimized.
• Well-documented, type-stable API.
• Storage mode per component for ergonomics and SIMD.
• Extensible event system with filtering and custom event types.
• Blazing fast batch entity creation.
• No systems. Just queries. Use your own structure.
• Minimal dependencies, 100% test coverage.

Entity Component Systems (ECS) offer a clean, scalable way to build individual- and agent-based models by separating agent data from behavioral logic. Agents are simply collections of components, while systems define how those components interact, making simulations modular, extensible, and efficient even with millions of heterogeneous individuals.

Ark.jl brings this architecture to Julia with a lightweight, performance-focused implementation that empowers scientific modellers to design complex and performant simulations without the need for deep software engineering expertise.

Run this to add Ark.jl to a Julia project:

using Pkg
Pkg.add("Ark")

Here is the classical Position/Velocity example that every ECS shows in the docs.

See the Manual, API docs and demos for more details.

using Ark

"""Position component"""
struct Position
    x::Float64
    y::Float64
end

"""Velocity component"""
struct Velocity
    dx::Float64
    dy::Float64
end

# Create a world with the required components
world = World(Position, Velocity)

for i in 1:1000
    # Create an entity with components
    entity = new_entity!(world, (Position(i, i * 2), Velocity(1, 1)))
end

# Time loop
for i in 1:10
    # Iterate a query (archetypes)
    for (entities, positions, velocities) in Query(world, (Position, Velocity))
        # Iterate entities in the current archetype
        @inbounds for i in eachindex(entities)
            # Get components of the current entity
            pos = positions[i]
            vel = velocities[i]
            # Update an (immutable) component
            positions[i] = Position(pos.x + vel.dx, pos.y + vel.dy)
        end
    end
end

Lange, M. & Meligrana, A. (2025): Ark.jl – An archetype-based Entity Component System for Julia. DOI: 10.5281/zenodo.17512271, GitHub repository: https://github.com/mlange-42/Ark.jl

Ark.jl and all its sources and documentation are distributed under the MIT license and the Apache 2.0 license, as your options.