Searching Kiwi Syslog Server by the REST API

I want programmatically search and fetch the logs that arrive to a Kiwi Syslog Server. Unfortunately I don't have an access to a server itself, so I cannot create forward rules. I also don't have an access to a logs database. If the REST API is not available the link to some open-source JavaScript Kiwi Log Viewer will also be fine, so I could see how it is implemented.

For example, the Loggly allows to do it by the HTTP request:
https://documentation.solarwinds.com/en/Success_Center/loggly/Content/admin/api-retrieving-data.htm?cshid=loggly_api-retrieving-data

and the Elasticsearch has the Search API:
https://www.elastic.co/guide/en/elasticsearch/reference/current/search-search.html