# useIsMutating

`useIsMutating` is an optional hook that returns the `number` of mutations that your application is fetching (useful for app-wide loading indicators).

```tsx
import { useIsMutating } from '@tanstack/react-query'
// How many mutations are fetching?
const isMutating = useIsMutating()
// How many mutations matching the posts prefix are fetching?
const isMutatingPosts = useIsMutating({ mutationKey: ['posts'] })
```

**Options**

- `filters?: MutationFilters`: [Mutation Filters](../../../../framework/react/guides/filters#mutation-filters)
- `context?: React.Context<QueryClient | undefined>`
  - Use this to use a custom React Query context. Otherwise, `defaultContext` will be used.

**Returns**

- `isMutating: number`
  - Will be the `number` of the mutations that your application is currently fetching.