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Cloud · head to head

Flux vs Eclipse Mosquitto

Flux logo

Flux

Cloud

GitOps continuous delivery for Kubernetes

From
Free
Rated
-
Full reviewWebsite
Eclipse Mosquitto logo

Eclipse Mosquitto

Networking

Small, EPL-licensed MQTT broker that runs on hardware other brokers cannot

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Flux no user interface of its own: observing what Flux is doing means CLI or a third-party dashboard; Eclipse Mosquitto there is no clustering: Mosquitto is a single process, so high availability means building your own failover and accepting session loss on switchover.
  • They diverge on capability: Flux covers Git as source of truth, Eclipse Mosquitto covers MQTT 5.0 support.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Flux and Eclipse Mosquitto actually diverge.

Attributes where Flux and Eclipse Mosquitto differ
AttributeFluxEclipse Mosquitto
PlatformsKubernetes, LinuxLinux, Windows, macOS, Docker
CategoryCloudNetworking

Identical on both: starting price (Free), pricing model (Open source, no licence fee), free tier (Yes), user rating (Not yet rated).

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 Flux

  • Git as source of truth
  • Pull-based delivery
  • Helm and Kustomize support
  • Automated image updates

Only in Eclipse Mosquitto

  • MQTT 5.0 support
  • Very small footprint
  • Bridging
  • WebSockets listener
  • Command line clients
  • Dynamic security plugin

What people use each for

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

Flux

  • Removing cluster credentials from CI systemsnot Eclipse Mosquitto
  • Keeping many clusters consistent with a single declared statenot Eclipse Mosquitto
  • Automatically correcting configuration drift rather than discovering it laternot Eclipse Mosquitto

Eclipse Mosquitto

  • A home or building automation stack where the broker must run on the same small computer as everything elsenot Flux
  • An industrial gateway that buffers local telemetry and bridges selected topics to a cloud brokernot Flux
  • Local development and testing of MQTT clients without provisioning a cloud IoT servicenot Flux
  • An air-gapped deployment where a broker with no licence server and no phone-home behaviour is a requirementnot Flux

Where each one falls short

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

Flux

  • No user interface of its own: observing what Flux is doing means CLI or a third-party dashboard
  • Debugging a stuck reconciliation is harder than reading a pipeline log, because failure is asynchronous
  • Everything must be in Git, which is awkward for secrets and needs a sealed-secrets or external-secrets approach
  • GitOps is a workflow change, not just a tool, and teams used to imperative deploys find the adjustment real

Eclipse Mosquitto

  • There is no clustering: Mosquitto is a single process, so high availability means building your own failover and accepting session loss on switchover.
  • Persistence is a local file rather than a replicated store, so a disk failure or an unclean shutdown can lose retained messages and queued QoS traffic.
  • Practical capacity is a few thousand concurrent clients on typical hardware, so a growing device fleet eventually forces a migration to a clustered broker.
  • The Eclipse Public Licence is weak copyleft rather than permissive, which some legal teams treat as a blocker when embedding the broker in a shipped commercial product.
  • There is no commercial support to buy from the project, so production incidents rely on community mailing lists or on paying a third party who happens to know the codebase.

Pricing, plan by plan

Flux

Free
  • FluxFree
    • Full functionality
    • No usage limits
    • Community support

Eclipse Mosquitto

Free
  • Eclipse MosquittoFree
    • Eclipse Public License 2.0 with Eclipse Distribution Licence
    • MQTT 5.0, 3.1.1 and 3.1
    • No client or message limits beyond your hardware

Which should you pick?

Choose Flux if

  • You need git as source of truth.
  • You want to start without paying.
  • You work on Kubernetes, Linux.
  • You also want pull-based delivery.
Flux review

Choose Eclipse Mosquitto if

  • You need mqtt 5.0 support.
  • You want to start without paying.
  • You work on Linux, Windows, macOS, Docker.
  • You also want very small footprint.
Eclipse Mosquitto review

Questions people ask

Is Flux or Eclipse Mosquitto better?
Neither clearly leads. Flux starts at Free and Eclipse Mosquitto at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Flux or Eclipse Mosquitto?
Flux starts at Free and Eclipse Mosquitto at Free.
Does Flux or Eclipse Mosquitto run on more platforms?
Flux runs on Kubernetes, Linux. Eclipse Mosquitto runs on Linux, Windows, macOS, Docker.
Can I use Flux for free?
Both have a free tier, so you can try either at no cost before committing.
What is Flux best used for?
Flux is most often used for removing cluster credentials from ci systems, keeping many clusters consistent with a single declared state, automatically correcting configuration drift rather than discovering it later. Of those, removing cluster credentials from ci systems and keeping many clusters consistent with a single declared state are not what Eclipse Mosquitto is typically brought in for.
What can Flux do that Eclipse Mosquitto cannot?
Flux covers Git as source of truth, Pull-based delivery, Helm and Kustomize support, Automated image updates. Eclipse Mosquitto covers MQTT 5.0 support, Very small footprint, Bridging, WebSockets listener.

Answered from the vendors’ own pages

Flux: Is Flux free?

Yes, open source and CNCF-graduated.

Eclipse Mosquitto: Can Mosquitto be clustered?

No. It is a single process. High availability requires an external failover arrangement you build yourself.

Flux: Flux or Argo CD?

Both implement GitOps. Argo CD ships a strong web UI and is often preferred for visibility; Flux is more modular and composes as controllers, which suits platform teams.

Eclipse Mosquitto: What licence is it?

Eclipse Public License 2.0 alongside the Eclipse Distribution License, a weak copyleft rather than a permissive licence.

Flux: Why is pull-based safer?

Because the cluster reaches out to Git rather than CI reaching into the cluster. No external system needs write credentials to production.

Eclipse Mosquitto: How many clients can it handle?

A few thousand concurrent connections on ordinary hardware; beyond that, use a clustered broker.

Eclipse Mosquitto: Does it support MQTT 5?

Yes, along with 3.1.1 and 3.1.

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