---
lang: en
title: 'API docs: core.serviceinterface'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/core
permalink: /doc/en/lb4/apidocs.core.serviceinterface.html
---

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[Home](./index.md) &gt; [@loopback/core](./core.md) &gt; [ServiceInterface](./core.serviceinterface.md)

## ServiceInterface type

Representing an interface for services. In TypeScript, the `interface` does not have reflections at runtime. We use a string, a symbol or a Function as the type for the service interface.

**Signature:**

```typescript
export type ServiceInterface = string | symbol | Function;
```