# Available Refiners

Each refiner is a small factory function that returns a `RefineTuple` — the
exact shape you spread into Zod's `.refine()`. You never install them as a
dependency; you copy their source into your project.

| Refiner                                        | Rule it enforces                      | Error lands on                          |
| ---------------------------------------------- | ------------------------------------- | --------------------------------------- |
| [`password-match`](/refiners/password-match)   | Two fields hold the same value        | The confirmation field                  |
| [`strong-password`](/refiners/strong-password) | Configurable password-strength policy | The password field                      |
| [`date-range`](/refiners/date-range)           | End date comes after start date       | The configured field (`end` by default) |
| [`allowed-domains`](/refiners/allowed-domains) | Email, URL, or hostname is allowlisted | The refined field                       |
| [`types`](/refiners/types)                     | Shared `RefineTuple` contract         | — installed automatically               |

Install any of them with:

```bash
npx zod-refiners add password-match-refiner
npx zod-refiners add strong-password-refiner
npx zod-refiners add date-range-refiner
npx zod-refiners add allowed-domains-refiner
```

:::tip
`types.ts` is never installed by name — it follows automatically whenever a
refiner needs it (see [`registryDependencies`](/cli)).
:::

## Design rules

1. **Pure predicates** — a refiner only reads the `data` it is given; no captured state, no I/O, no throwing.
2. **Honest paths** — `path` always points at the field responsible for the failure.
3. **Composition over configuration** — every refiner handles exactly one concern; combine ten and each error still lands on its own field.