Fluent Bit review 2026: a CNCF graduated, open-source log and metrics forwarder from Treasure Data. See features, architecture, pricing, and alternatives.
Fluent Bit is a free, open-source telemetry pipeline that collects logs, metrics, and traces from a wide variety of sources and forwards them to a wide variety of destinations. Written in C, it is designed for minimal CPU and memory overhead, which has made it the default log and metrics agent in many Kubernetes distributions and managed cloud platforms.
The project was created in 2014 by Eduardo Silva while working on the Fluentd team at Treasure Data, as a lighter-weight companion to Fluentd for embedded Linux devices and network gateways. It is now a CNCF graduated project under the Fluent project umbrella alongside Fluentd, reflecting its status as production-proven infrastructure software used across thousands of organizations.
Fluent Bit's pipeline is built from inputs, parsers, filters (processors), and outputs, with more than 100 built-in plugins covering sources like container runtimes, systemd, syslog, and HTTP, and destinations like Elasticsearch, OpenSearch, Splunk, Amazon S3, CloudWatch, Kafka, Loki, and Fluentd itself.
Recent major versions added native OpenTelemetry Protocol (OTLP) ingestion and egress, SQL-like stream processing over telemetry records, and support for WebAssembly filter and input plugins, extending Fluent Bit beyond classic log shipping into a general-purpose observability edge agent.
Fluent Bit is event-driven and asynchronous, using chunk-based buffering that can operate in memory or spill to disk, and a tag-based routing engine that lets a single process ingest from many sources and dispatch to many destinations concurrently without duplicating pipelines.
It is most commonly deployed as a per-node DaemonSet in Kubernetes clusters, and is embedded as default or supported tooling in Amazon ECS/Fargate (via FireLens), Amazon EKS, Google Kubernetes Engine, and other managed platforms. Its small binary size and lack of external dependencies also make it well suited to edge computing, IoT gateways, and embedded Linux devices, close to its original 2014 design goal.
Yes. Fluent Bit is fully open source under the Apache License 2.0, and there is no cost to download, self-host, or modify it for commercial or personal use.
Fluent Bit was created in 2014 by Eduardo Silva while he was working on the Fluentd team at Treasure Data, as a lighter-weight companion project for embedded and constrained environments.
Yes. Fluent Bit is a CNCF graduated project within the Fluent project umbrella alongside Fluentd, the Cloud Native Computing Foundation's highest maturity classification.
Fluent Bit is written in C and designed for minimal footprint and high performance in constrained or edge environments, while Fluentd is written in Ruby with C extensions and offers a larger plugin ecosystem better suited to heavier central aggregation. The two are commonly used together.
Chronosphere, which acquired Calyptia (founded in 2020 by Fluent Bit's original creators) in January 2024, is the primary corporate sponsor of Fluent Bit and offers a commercial Telemetry Pipeline product and enterprise support built on the open-source project.
Fluent Bit now supports native OpenTelemetry Protocol (OTLP) ingestion and export, allowing it to interoperate with or serve as a lightweight alternative to the OpenTelemetry Collector, particularly in resource-constrained or edge deployments.