Thanks for your inquiry. Can you please confirm you are looking for some on-premise API solution or REST API solution?
If you are interested in the REST API solution then you can use Aspose.Words REST API in your application. It can be used with any language/platform that supports REST. I’m afraid currently we do not have any ready to use example, but you may use Aspose.Words REST API using Angular HttpClient.
However, if you are looking for an on-premise API solution then you can use GroupDocs.Editor for .NET to edit the documents in your application. Please check sample project using GroupDocs.Editor for .NET with Angular.