@eristack/money

JSR 354–inspired money primitives for ERP and business software.

• Immutable Money amounts with strict currency checks
• Adaptive bigint / decimal engine
• Rounding, allocate/split, formatting, and app-supplied FX conversion

Install

pnpm add @eristack/money

Quick example

import { Money, Rounding, Tax } from "@eristack/money";

const price = Money.of("19.99", "USD");
const tax = price.percentOf("7").with(Rounding.currencyDefault());
const total = Money.sum([price, tax]);

console.log(total.toJSON());
// { currency: "USD", amount: "21.39" }

// Or: price.with(Tax.onExclusive("7")).with(Rounding.currencyDefault())

Documentation

• Source of truth: docs/ (markdown + docs/_meta.json)
• Website: rendered by apps/web at /docs/money (Cmd/Ctrl+K search on the site)

Guides:

• Overview
• Getting started
• Advanced arithmetic (totals, %, tax/discount)
• ERP recipes
• API reference

AI agent skills

This package ships Agent Skills via TanStack Intent:

• @eristack/money#money-amounts — construct amounts and same-currency arithmetic
• @eristack/money#money-ledger — rounding, allocate, FX conversion, JSON

If you use an AI coding agent, run:

npx @tanstack/intent@latest install
npx @tanstack/intent@latest list
npx @tanstack/intent@latest load @eristack/money#money-amounts