[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Type](https://evolu.dev/docs/api-reference/common/Type) › Port

```ts
type Port = number &
  Brand<"NonNaN"> &
  Brand<"Finite"> &
  Brand<"Int"> &
  Brand<"NonNegative"> &
  Brand<"LessThanOrEqualTo65535"> &
  Brand<"Port">;
```

Defined in: [packages/common/src/Type.ts:8353](https://github.com/evoluhq/evolu/blob/dd96d79f1dbe9a49fa12ce8e0aa7d3d0177795ca/packages/common/src/Type.ts#L8353)

A TCP or UDP port as an integer from zero through 65535, inclusive.

When binding a server, zero requests an automatically assigned port. Use
[PortFromString](https://evolu.dev/docs/api-reference/common/Type/variables/PortFromString) for configuration values supplied as text.

### Example

```ts

assertOk(Port.fromUnknown(0), 0);
assertOk(Port.fromUnknown(4000), 4000);
assertOk(Port.fromUnknown(65535), 65535);
assertErr(Port.fromUnknown(-1));
assertErr(Port.fromUnknown(65536));
assertErr(Port.fromUnknown(4000.5));
```