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Software · head to head

Fluent Bit vs Loki

Fluent Bit logo

Fluent Bit

Software

Fast and Lightweight Log Processor

From
Free
Rated
-
Full reviewWebsite
Loki logo

Loki

Software

Like Prometheus but for Logs

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Fluent Bit fluent Bit ships over 100 built in plugins against more than 1,000 external plugins available for Fluentd, so fewer integrations exist out of the box; Loki the Grafana Cloud free tier caps log ingestion at 50 GB a month with 14 day retention
  • They diverge on capability: Fluent Bit covers Log collection, Loki covers Log aggregation.

Where they differ

Only the attributes on which Fluent Bit and Loki actually diverge.

Attributes where Fluent Bit and Loki differ
AttributeFluent BitLoki
Founded20152014

Identical on both: starting price (Free), pricing model (open-source), free tier (Yes), platforms (Web, Api), user rating (Not yet rated), category (Unknown).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Fluent Bit

  • Log collection
  • Lightweight processing
  • Data parsing
  • Event filtering

Only in Loki

  • Log aggregation
  • Label-based indexing
  • Real-time log streaming
  • LogQL query language

Both cover

  • API
  • Webhooks
  • REST
  • Web support
  • Api support

What people use each for

The jobs each tool is most often brought in to do.

Fluent Bit

  • Lightweight log and metric forwarding from containers and edge devicesnot Loki
  • Kubernetes node level log collection with a small memory footprintnot Loki
  • Filtering and enriching telemetry before shipping it to a backendnot Loki

Loki

  • Aggregating application and infrastructure logs with label based indexingnot Fluent Bit
  • Querying logs alongside metrics in Grafananot Fluent Bit

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Fluent Bit

  • Fluent Bit ships over 100 built in plugins against more than 1,000 external plugins available for Fluentd, so fewer integrations exist out of the box
  • It is written in C, so extending it beyond the built in plugins means writing C rather than Ruby
  • Dependencies are zero only until a plugin requires one

Loki

  • The Grafana Cloud free tier caps log ingestion at 50 GB a month with 14 day retention
  • Paid log pricing is split across three separate meters, at $0.050 per GB processed, $0.400 per GB written and $0.100 per GB retained
  • Retaining logs is billed separately from ingesting them, so keeping data costs on an ongoing basis rather than once
  • The Pro plan carries a $19 a month platform fee before any usage charges

Pricing, plan by plan

Fluent Bit

Free
  • FreeFree
    • Log collection
    • Lightweight processing
    • Data parsing

Loki

Free
  • FreeFree
    • Log aggregation
    • Label-based indexing
    • Real-time log streaming

Which should you pick?

Choose Fluent Bit if

  • You need log collection.
  • You want to start without paying.
  • You work on Web, Api.
  • You also want lightweight processing.
Fluent Bit review

Choose Loki if

  • You need log aggregation.
  • You want to start without paying.
  • You work on Web, Api.
  • You also want label-based indexing.
Loki review

Questions people ask

Is Fluent Bit or Loki better?
Neither clearly leads. Fluent Bit starts at Free and Loki at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Fluent Bit or Loki?
Fluent Bit starts at Free and Loki at Free.
Does Fluent Bit or Loki run on more platforms?
Both run on Web, Api, so platform support will not decide this one for you.
Can I use Fluent Bit for free?
Both have a free tier, so you can try either at no cost before committing.
What is Fluent Bit best used for?
Fluent Bit is most often used for lightweight log and metric forwarding from containers and edge devices, kubernetes node level log collection with a small memory footprint, filtering and enriching telemetry before shipping it to a backend. Of those, lightweight log and metric forwarding from containers and edge devices and kubernetes node level log collection with a small memory footprint are not what Loki is typically brought in for.
What can Fluent Bit do that Loki cannot?
Fluent Bit covers Log collection, Lightweight processing, Data parsing, Event filtering. Loki covers Log aggregation, Label-based indexing, Real-time log streaming, LogQL query language. Both handle API, Webhooks, REST, Web support.
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