[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [local‑first/Evolu](https://evolu.dev/docs/api-reference/common/local-first/Evolu) › AppName

```ts
const AppName: brand("AppName", UrlSafeString, (value) =>
  value.length >= 1 && value.length <= 41
    ? ok(value)
    : err<AppNameError>({ type: "AppName", value }),
);
```

Defined in: [packages/common/src/local-first/Evolu.ts:246](https://github.com/evoluhq/evolu/blob/e7144e2bbe9069362b62dec1b64a8aa922b8f1b0/packages/common/src/local-first/Evolu.ts#L246)

Application name.

Evolu uses AppName as the base prefix for [Evolu.name](https://evolu.dev/docs/api-reference/common/local-first/Evolu/interfaces/Evolu#name). The final
instance name is derived per [AppOwner](https://evolu.dev/docs/api-reference/common/local-first/Owner/interfaces/AppOwner) as
`${appName}-${createIdFromString(appOwner.id)}`.

Uses the same safe alphabet as [UrlSafeString](https://evolu.dev/docs/api-reference/common/Type/variables/UrlSafeString) (letters, digits, `-`,
`_`) and must be between 1 and 41 characters.