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Logging · head to head

Fluentd vs Logstash

Fluentd logo

Fluentd

Logging

Open Source Data Collector for Unified Logging

From
Free
Rated
-
Full reviewWebsite
Logstash logo

Logstash

Logging

Data Processing Pipeline for Ingestion

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Fluentd fluentd needs more than 60 MB of memory at runtime, against roughly 450 KB for Fluent Bit; Logstash logstash's source is dual licensed: code outside the x-pack directory is Apache License 2.0, but code inside x-pack (which carries several of Logstash's monitoring and management features) is licensed under the Elastic License, not a fully open source license
  • They diverge on capability: Fluentd covers Log collection, Logstash covers Data ingestion.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Fluentd and Logstash actually diverge.

Attributes where Fluentd and Logstash differ
AttributeFluentdLogstash

Identical on both: starting price (Free), pricing model (open-source), free tier (Yes), platforms (Web, Api), user rating (Not yet rated), category (Logging), founded (2011).

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 Fluentd

  • Log collection
  • Data parsing
  • Filtering and buffering
  • Event routing

Only in Logstash

  • Data ingestion
  • Event parsing
  • Data transformation
  • Multiple input sources

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.

Fluentd

  • Unified log collection and routing from many sources to many destinationsnot Logstash
  • Parsing and transforming log records before forwardingnot Logstash
  • Aggregating logs from containers into Elasticsearch, S3 or a SIEMnot Logstash

Logstash

  • Log monitoringnot Fluentd
  • Application performancenot Fluentd
  • Security analyticsnot Fluentd
  • Troubleshootingnot Fluentd

Where each one falls short

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

Fluentd

  • Fluentd needs more than 60 MB of memory at runtime, against roughly 450 KB for Fluent Bit
  • Fluentd is built as a Ruby gem and depends on other gems, so a Ruby runtime is required
  • Its capability comes from over 1,000 external plugins rather than built in functionality, so each added input or output is a separate dependency
  • The Fluent Bit documentation states that cloud providers have switched from Fluentd to Fluent Bit for performance and compatibility and calls Fluent Bit the next generation solution

Logstash

  • Logstash's source is dual licensed: code outside the x-pack directory is Apache License 2.0, but code inside x-pack (which carries several of Logstash's monitoring and management features) is licensed under the Elastic License, not a fully open source license

Pricing, plan by plan

Fluentd

Free
  • FreeFree
    • Log collection
    • Data parsing
    • Filtering and buffering

Logstash

Free
  • FreeFree
    • Data ingestion
    • Event parsing
    • Data transformation

Which should you pick?

Choose Fluentd if

  • You need log collection.
  • You want to start without paying.
  • You work on Web, Api.
  • You also want data parsing.
Fluentd review

Choose Logstash if

  • You need data ingestion.
  • You want to start without paying.
  • You work on Web, Api.
  • You also want event parsing.
Logstash review

Questions people ask

Is Fluentd or Logstash better?
Neither clearly leads. Fluentd starts at Free and Logstash at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Fluentd or Logstash?
Fluentd starts at Free and Logstash at Free.
Does Fluentd or Logstash run on more platforms?
Both run on Web, Api, so platform support will not decide this one for you.
Can I use Fluentd for free?
Both have a free tier, so you can try either at no cost before committing.
What is Fluentd best used for?
Fluentd is most often used for unified log collection and routing from many sources to many destinations, parsing and transforming log records before forwarding, aggregating logs from containers into elasticsearch, s3 or a siem. Of those, unified log collection and routing from many sources to many destinations and parsing and transforming log records before forwarding are not what Logstash is typically brought in for.
What can Fluentd do that Logstash cannot?
Fluentd covers Log collection, Data parsing, Filtering and buffering, Event routing. Logstash covers Data ingestion, Event parsing, Data transformation, Multiple input sources. Both handle API, Webhooks, REST, Web support.

Answered from the vendors’ own pages

Fluentd: How much does Fluentd cost?

Fluentd is free and open-source under the Apache 2 License from the Cloud Native Computing Foundation (CNCF). There are no subscription fees, licensing costs, or commercial pricing tiers.

Source
Logstash: How much does Logstash cost?

Logstash is free and open-source. The data processing pipeline is available to download at no charge and can be deployed without licensing costs or commercial restrictions.

Source
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