A small family of Elixir libraries for working with money — the data type, the database, and the form input — built on top of CLDR via the localize package so that every layer is currency- and locale-aware out of the box.

Floats are wrong for money. Strings are wrong for arithmetic. Two-tuple {amount, currency} shapes break the moment you cross a system boundary. A library that gets this right has to do four things well:

• Represent money as arbitrary-precision decimal paired with a valid currency code (ISO 4217 fiat or ISO 24165 digital token).
• Enforce that arithmetic only happens between the same currency — at compile time where possible, at runtime where not.
• Round according to the currency's actual rules, not a generic "two decimal places" — JPY has zero fractional digits, BHD has three, CHF rounds cash to the nearest five rappen.
• Format and parse against CLDR locale data — "1.234,56 €" is correct German output, not a quirk to be normalised away.

Three sibling packages divide the work along clean seams. Each is independently usable; together they cover the round-trip from a user typing in a form field to a row in Postgres and back.

The Money.t/0 struct, its arithmetic (add, sub, mult, div, cmp, split, round), parsing (Money.parse/2 — handles symbols, ISO codes, accounting parens, locale-aware separators), and formatting (Money.to_string/2). Currency metadata covers all current and historical ISO 4217 codes plus ISO 24165 digital tokens. FX support via configurable rate providers.

Use it standalone for any calculation, conversion, or display work — no Phoenix, no database, no JS.

Money.Ecto.Composite.Type for Postgres (a real composite type that round-trips amount and currency in one column), Money.Ecto.Map.Type for MySQL (JSON with the decimal as a string to preserve precision), and the migration helpers that create them. Queries can filter and sort on the composite type directly; aggregates compose cleanly.

Use it whenever a money value needs to land in a relational database without losing the currency.

The <.money_input> and <.currency_picker> HEEx components, an AutoNumeric-backed JS hook for live formatting and cursor preservation, an Ecto changeset bridge (cast_money, validate_money), and a Plug-based visualizer for previewing every component × locale × currency combination during development.

Submits a %{"amount", "currency"} map that Money.Ecto.Composite.Type casts directly — no custom param-flattening, no canonical-vs-locale ambiguity on the wire. Use it whenever a user types money into a form.

For plain locale-aware number input (no currency), see the sibling localize_inputs package — same architecture, no currency layer.

money_input_playground is a small Fly.io-deployable wrapper around the ex_money_input visualizer. It runs the real HEEx components across every locale and currency, with AutoNumeric mounted, so you can see what your users would see without setting up a project first.

Live instance: https://elixir-money-input.fly.dev.

Not a library — it's a deployment shell (Bandit + a host router that adds favicon, robots.txt, /healthz, and forwards to Money.Input.Visualizer). The ex_money_input library itself is unchanged.

All three packages are Apache-2.0.