What is Acore?

Acore is AxiomCore's independent, declarative language for describing software contracts. It has typed declarations, composition, validation, a standard library, diagnostics and editor support. A .acore file is source code. It is not the artifact a consumer locks and runs; the Axiom CLI builds that from it.

A small example

This file defines a model, an action that returns it, and a public endpoint that runs the action:

project(id: "docs.hello", version: "1.0.0")
variant default(include: ["*"])
model Greeting { message: String }
action hello(kind: ActionKind.query, output: Models.Greeting) {
  managed { return {message: "Hello from Acore"} }
}
endpoint hello(method: GET, path: "/hello") {
  handle(action: Actions.hello)
  response(type: Models.Greeting)
}

axiom check main.acore validates it, and axiom build turns it into a .axiom contract. Build your first API runs it.

What Acore can describe

• Backend routes, models, caching, retry, authentication, validation, streaming and mock behavior.
• Durable domain entities, relationships, invariants, projections and security declarations.
• Acore UI trees: typed text and layout, interactions, effects, assets and target-specific application builds.
• Use of typed theme and component-library packages.
• Versioned package boundaries for services, themes, component libraries, database schemas, extensions and application policies.

Not every kind has the same authoring or runtime surface yet. The support matrix gives the current boundary.

Source, contract and application

Diagram source

flowchart LR
  A[.acore source] -->|axiom build| B[.axiom contract or package]
  B -->|pinned in a lock| C[Consumers]
  A -->|axiom ui build| D[.axiomapp application]

Composition keywords

import "./shared.acore"
amends "axiom-fastapi:./app.py:app"
use contract Billing from "billing" audience "mobile"
use theme AppTheme from "design-system" export "default"

Imports, amends and variants covers ownership and trust boundaries.

Acore is optional at integration edges

You do not have to rewrite an application. Existing Python and Go services take part through supported extractors. Existing web, React, Flutter and Swift apps keep their current integration paths. Use Acore where declarative behavior and auditable composition help.

Next steps

• Acore language overview
• Build your first API
• Use your existing stack