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Networking · head to head

Eclipse Mosquitto vs Swagger UI

Eclipse Mosquitto logo

Eclipse Mosquitto

Networking

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

From
Free
Rated
-
Full reviewWebsite
Swagger UI logo

Swagger UI

Developer Tools

Interactive API documentation generated from OpenAPI specs

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: 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.; Swagger UI only as good as the specification: a thin OpenAPI file produces thin documentation
  • They diverge on capability: Eclipse Mosquitto covers MQTT 5.0 support, Swagger UI covers OpenAPI rendering.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Eclipse Mosquitto and Swagger UI actually diverge.

Attributes where Eclipse Mosquitto and Swagger UI differ
AttributeEclipse MosquittoSwagger UI
PlatformsLinux, Windows, macOS, DockerWeb, Self-hosted, Docker
CategoryNetworkingDeveloper Tools

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 Eclipse Mosquitto

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

Only in Swagger UI

  • OpenAPI rendering
  • Try it out
  • Schema display
  • Self-hostable

What people use each for

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

Eclipse Mosquitto

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

Swagger UI

  • Publishing API documentation that stays in step with the specificationnot Eclipse Mosquitto
  • Letting developers try endpoints before writing any client codenot Eclipse Mosquitto
  • Internal API discovery across teamsnot Eclipse Mosquitto

Where each one falls short

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

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.

Swagger UI

  • Only as good as the specification: a thin OpenAPI file produces thin documentation
  • Default presentation is dated compared with modern documentation tools
  • Large specifications render slowly and become hard to navigate
  • Try it out against production needs care with authentication and CORS, and is often disabled as a result

Pricing, plan by plan

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

Swagger UI

Free
  • Swagger UIFree
    • Full functionality
    • Commercial use permitted
    • Community support

Which should you pick?

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

Choose Swagger UI if

  • You need openapi rendering.
  • You want to start without paying.
  • You work on Web, Self-hosted, Docker.
  • You also want try it out.
Swagger UI review

Questions people ask

Is Eclipse Mosquitto or Swagger UI better?
Neither clearly leads. Eclipse Mosquitto starts at Free and Swagger UI at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Eclipse Mosquitto or Swagger UI?
Eclipse Mosquitto starts at Free and Swagger UI at Free.
Does Eclipse Mosquitto or Swagger UI run on more platforms?
Eclipse Mosquitto runs on Linux, Windows, macOS, Docker. Swagger UI runs on Web, Self-hosted, Docker.
Can I use Eclipse Mosquitto for free?
Both have a free tier, so you can try either at no cost before committing.
What is Eclipse Mosquitto best used for?
Eclipse Mosquitto is most often used for a home or building automation stack where the broker must run on the same small computer as everything else, an industrial gateway that buffers local telemetry and bridges selected topics to a cloud broker, local development and testing of mqtt clients without provisioning a cloud iot service, an air-gapped deployment where a broker with no licence server and no phone-home behaviour is a requirement. Of those, a home or building automation stack where the broker must run on the same small computer as everything else and an industrial gateway that buffers local telemetry and bridges selected topics to a cloud broker are not what Swagger UI is typically brought in for.
What can Eclipse Mosquitto do that Swagger UI cannot?
Eclipse Mosquitto covers MQTT 5.0 support, Very small footprint, Bridging, WebSockets listener. Swagger UI covers OpenAPI rendering, Try it out, Schema display, Self-hostable.

Answered from the vendors’ own pages

Eclipse Mosquitto: Can Mosquitto be clustered?

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

Swagger UI: Is Swagger UI free?

Yes, open source under the Apache 2.0 licence. SmartBear sells commercial SwaggerHub separately.

Eclipse Mosquitto: What licence is it?

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

Swagger UI: What is the difference between Swagger and OpenAPI?

OpenAPI is the specification format; Swagger is the toolset around it, including Swagger UI. The specification was renamed from Swagger to OpenAPI in 2016.

Eclipse Mosquitto: How many clients can it handle?

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

Swagger UI: Can Swagger UI make real API calls?

Yes, through its try-it-out control, though authentication and CORS configuration often mean it is disabled for production APIs.

Eclipse Mosquitto: Does it support MQTT 5?

Yes, along with 3.1.1 and 3.1.

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