What is the opensource alternative for logstash?

can anyone tell me the opensource alternative for logstash ?

Data Prepper - You can find more information here:

opensearch-project/data-prepper: Data Prepper is a component of the OpenSearch project that accepts, filters, transforms, enriches, and routes data at scale. (github.com)

Data Prepper vs. Logstash: Overview, Components, Usage & More (opster.com)

Fluentd, Filebeat, vector are the alternatives to logstash.

Yes Fluentd is an opensource alternative for logstash. It is an robust and log collector, that allows you to collect praise, filter, route logs from source to destination form.