> For the complete documentation index, see [llms.txt](https://docs.internetobject.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.internetobject.org/schema-definition-language/data-types/bigint.md).

# BigInt

The **`bigint`** type validates an arbitrary-precision integer — values too large for the double-based `number` family (see [Numeric Types](/schema-definition-language/data-types/number.md)). In data it is written with an `n` suffix: `123n`, `0xFFn`.

> For the literal syntax, see [BigInt values](/structure-and-syntax/values/number/bigint.md).

## TypeDef

A `bigint` MemberDef accepts only the options below. Any other key is invalid.

| Option       | Type            | Description                                                        |
| ------------ | --------------- | ------------------------------------------------------------------ |
| `type`       | string          | The type name `bigint`. First positional value.                    |
| `default`    | bigint          | Value used when the member is omitted. Second positional value.    |
| `choices`    | array of bigint | Restricts the value to a fixed set.                                |
| `min`        | bigint          | Minimum allowed value (inclusive).                                 |
| `max`        | bigint          | Maximum allowed value (inclusive).                                 |
| `multipleOf` | bigint          | The value must be an exact multiple of this.                       |
| `format`     | string          | Serialization base: `decimal` (default), `hex`, `octal`, `binary`. |
| `optional`   | bool            | If `true`, the member may be omitted. Shorthand: `?` suffix.       |
| `null`       | bool            | If `true`, the member may be `null`. Shorthand: `*` suffix.        |

## Examples

```ruby
id: bigint
---
~ 123n                  # ✓
~ 0xFFn                 # ✓ (255)
~ 99999999999999999999999999999n   # ✓
```

```ruby
big: { bigint, min: 100n }
---
~ 50n     # ✗ invalid-range
```

## Optional, nullable & defaults

Resolution follows the [common rules](/schema-definition-language/data-types/number.md#optional-nullable--defaults):

```ruby
id?*: bigint    # optional + nullable
---
~ {}     # ✓ omitted → absent
~ N      # ✓ null
~ 7n     # ✓
```

## Implementation status (beta)

* Keyed `null:` is not yet honored — use the `*` suffix.

## See Also

* [BigInt values](/structure-and-syntax/values/number/bigint.md)
* [Numeric Types](/schema-definition-language/data-types/number.md) · [Decimal](/schema-definition-language/data-types/decimal.md)
* [TypeDef](/schema-definition-language/advanced-schema-concepts/typedef.md) · [MemberDef](/schema-definition-language/advanced-schema-concepts/memberdef.md)


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