From my little knowledge of Loki's internals. I think contrary to Loki, Quickwit uses a fully feature search engine library underneath called Tantivy (https://github.com/quickwit-oss/tantivy). Quickwit offers different services (indexer, searcher, ..) that can be ran and scaled independently. It also supports indexing from various sources including file, Rest API, Kafka, Pulsar, Kinesis and more are planned based on community interest. Last but not least, Elasticsearch query API support is being worked on.