Fluent Bit vs Fluentd

Fluent Bit is a free, open-source telemetry agent for collecting and processing logs, metrics, and traces. It can run as an edge agent on constrained systems or as a central collector for cloud infrastructure, and is designed for high throughput with low resource consumption. Built-in parsers cover JSON, Regex, LTSV, and Logfmt; metrics compatibility includes Prometheus and OpenTelemetry. More than 100 built-in plugins cover inputs, filters, analytics, and outputs, with destinations including Splunk, Elasticsearch, OpenSearch, and Kafka. Buffering in memory or on the file system and backpressure handling support data flow, while network input and output plugins include TLS and SSL. Stream processing supports SQL queries, aggregation windows, forecasting, and data analysis. Users can write plugins in C, Lua, Golang, or WebAssembly. The Open-source Fluent Bit plan costs nothing, with self-hosted deployment under the Apache License 2.0. Official packages and installation guidance cover Linux, macOS, Windows, containers, and selected BSD and IBM Z Linux environments.

Fluentd is a free, open-source data collector for creating a unified logging layer. It uses JSON to handle log collection, filtering, buffering, and output across sources and destinations. More than 500 community plugins connect it to data sources and outputs, including Elasticsearch and Kibana, Splunk, AWS S3, Kafka, BigQuery, Datadog, and OpenTelemetry. It supports memory and file buffering, failover, and high availability to help prevent data loss between nodes. The project reports that a vanilla instance uses 30–40 MB of memory and can process 13,000 events per second per core. Fluentd v1 runs on Linux, Mac OSX, and Windows; community distributions also include Docker images, a Kubernetes DaemonSet, and Ruby gems. It is self-hosted, and its components are available under the Apache 2 License. The project lists community help and commercial support from companies offering enterprise services. The homepage notes vulnerabilities patched in Fluentd v1.19.3 and advises updating fluent-package to v6.0.4.