Fluent Bit is a free, open-source telemetry agent for collecting and processing logs, metrics, and traces across constrained systems and cloud infrastructure. It can run as an edge agent or as a central aggregator or collector, and is designed for high throughput with low resource use. Built-in parsers support JSON, Regex, LTSV, and Logfmt, while metrics compatibility includes Prometheus and OpenTelemetry. Buffering can use memory or the file system, and the agent provides backpressure handling. Network input and output plugins include TLS and SSL support. More than 100 built-in plugins cover inputs, filters, analytics, and outputs; destinations include Splunk, Elasticsearch, OpenSearch, and Kafka. Users can create plugins in C, Lua, Golang, or WebAssembly. Stream processing supports SQL queries, aggregation windows, forecasting, and data analysis. Fluent Bit is distributed under the Apache License 2.0, with official packages or installation guidance for Linux, macOS, Windows, containers, and selected BSD and IBM Z Linux environments. Support for plugins and filters varies across platforms.
Who it is for
Fluent Bit may suit teams that need to collect and process telemetry at the edge or in cloud infrastructure. Its plugin options and self-hosted deployment may also fit users who want to route telemetry to multiple destinations.
What is good
- Processes logs, metrics, and traces
- Offers more than 100 built-in plugins
- Supports buffering and backpressure handling
- TLS and SSL support for network plugins
- Free under the Apache License 2.0
What to know first
- Not all plugins and filters work on BSD
- Plugin and filter support varies by platform
Verdict
Fluent Bit brings collection, processing, buffering, and routing into a free, self-hosted agent. Review platform-specific plugin and filter support before selecting a deployment environment.
Fluent Bit plans and pricing
All plansCompared on telemetry pipeline software
- Free plan
- No
- Logs support
- Yes
- Metrics support
- Yes
- Traces support
- Yes
- Transform rules
- Yes
- Multi-destination routing
- Yes
- Data enrichment
- Yes
- Deployment model
- self_hosted
