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Logging · head to head

Azure Monitor vs Fluent Bit

Azure Monitor logo

Azure Monitor

Logging

Azure's Monitoring and Diagnostics Service

From
Free
Rated
-
Full reviewWebsite
Fluent Bit logo

Fluent Bit

Logging

Fast and Lightweight Log Processor

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Azure Monitor billed per GB ingested across three separate log plans, Auxiliary, Basic and Analytics, so the plan chosen changes the rate as much as the volume does; 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
  • They diverge on capability: Azure Monitor covers Metrics collection, Fluent Bit covers Lightweight processing.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Azure Monitor and Fluent Bit actually diverge.

Attributes where Azure Monitor and Fluent Bit differ
AttributeAzure MonitorFluent Bit
Pricing modelusage-basedopen-source
Founded20102015

Identical on both: starting price (Free), free tier (Yes), platforms (Web, Api), user rating (Not yet rated), category (Logging).

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 Azure Monitor

  • Metrics collection
  • Alerts and notifications
  • Custom dashboards

Only in Fluent Bit

  • Lightweight processing
  • Data parsing
  • Event filtering

Both cover

  • Log collection
  • API
  • Webhooks
  • REST
  • Web support
  • Api support

What people use each for

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

Azure Monitor

  • Collecting logs and metrics from Azure resourcesnot Fluent Bit
  • Alerting on metric thresholds and log queriesnot Fluent Bit
  • Application performance monitoring through Application Insightsnot Fluent Bit
  • Long-term log retention for compliancenot Fluent Bit
  • Querying operational data with KQLnot Fluent Bit

Fluent Bit

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

Where each one falls short

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

Azure Monitor

  • Billed per GB ingested across three separate log plans, Auxiliary, Basic and Analytics, so the plan chosen changes the rate as much as the volume does
  • Only the first 5 GB a month of Analytics logs is free per billing account
  • Retention beyond the base period is charged per GB per month, up to 2 years interactive and 12 years long term
  • Log queries and search jobs are billed per GB scanned, so investigating an incident costs money
  • Alert rules are billed per time series for metrics and by execution frequency for logs
  • The pricing page shows placeholders rather than rates until a region and currency are chosen

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

Pricing, plan by plan

Azure Monitor

Free
  • FreeFree
    • Log collection
    • Metrics collection
    • Alerts and notifications

Fluent Bit

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

Which should you pick?

Choose Azure Monitor if

  • You need metrics collection.
  • You want to start without paying.
  • You work on Web, Api.
  • You also want alerts and notifications.
Azure Monitor review

Choose Fluent Bit if

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

Questions people ask

Is Azure Monitor or Fluent Bit better?
Neither clearly leads. Azure Monitor starts at Free and Fluent Bit at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Azure Monitor or Fluent Bit?
Azure Monitor starts at Free and Fluent Bit at Free.
Does Azure Monitor or Fluent Bit run on more platforms?
Both run on Web, Api, so platform support will not decide this one for you.
Can I use Azure Monitor for free?
Both have a free tier, so you can try either at no cost before committing.
What is Azure Monitor best used for?
Azure Monitor is most often used for collecting logs and metrics from azure resources, alerting on metric thresholds and log queries, application performance monitoring through application insights, long-term log retention for compliance. Of those, collecting logs and metrics from azure resources and alerting on metric thresholds and log queries are not what Fluent Bit is typically brought in for.
What can Azure Monitor do that Fluent Bit cannot?
Azure Monitor covers Metrics collection, Alerts and notifications, Custom dashboards. Fluent Bit covers Lightweight processing, Data parsing, Event filtering. Both handle Log collection, API, Webhooks, REST.

Answered from the vendors’ own pages

Azure Monitor: How does Azure Monitor billing work?

Billing is based on data volume ingested into Azure Monitor. Additional charges apply separately for alerts, notifications, web tests, and data export. Activity log and platform metrics are automatically collected with an Azure subscription.

Source
Fluent Bit: Is Fluent Bit free?

Yes, Fluent Bit is a CNCF graduated open-source project with no vendor lock-in and is freely available for download and use.

Source
Azure Monitor: What savings are available with Azure Monitor?

Capacity reservations offer up to 36% savings compared to standard pay-as-you-go pricing when you commit to reserved capacity upfront.

Source
Fluent Bit: Does Fluent Bit offer an Enterprise option?

The website navigation mentions an Enterprise section suggesting paid offerings exist, but specific pricing and details are not provided on the publicly available pages.

Source
Azure Monitor: Is there a free tier for Azure Monitor?

No dedicated free tier exists. Activity log and platform metrics are automatically collected with an Azure subscription, but detailed monitoring requires additional configuration and associated costs.

Source
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