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Networking · head to head

Eclipse Mosquitto vs OpenSearch

Eclipse Mosquitto logo

Eclipse Mosquitto

Networking

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

From
Free
Rated
-
Full reviewWebsite
OpenSearch logo

OpenSearch

Databases

Open-source search and analytics suite forked from Elasticsearch

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.; OpenSearch diverged from Elasticsearch since 7.10, so clients, plugins and features no longer map one to one
  • They diverge on capability: Eclipse Mosquitto covers MQTT 5.0 support, OpenSearch covers Full-text search.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

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

Attributes where Eclipse Mosquitto and OpenSearch differ
AttributeEclipse MosquittoOpenSearch
Pricing modelOpen source, no licence feeOpen source, no licence fee; managed services billed separately
PlatformsLinux, Windows, macOS, DockerLinux, Docker, Kubernetes, Self-hosted
CategoryNetworkingDatabases

Identical on both: starting price (Free), 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 OpenSearch

  • Full-text search
  • OpenSearch Dashboards
  • Log analytics
  • Vector search

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 OpenSearch
  • An industrial gateway that buffers local telemetry and bridges selected topics to a cloud brokernot OpenSearch
  • Local development and testing of MQTT clients without provisioning a cloud IoT servicenot OpenSearch
  • An air-gapped deployment where a broker with no licence server and no phone-home behaviour is a requirementnot OpenSearch

OpenSearch

  • Log and observability storage where an Apache-2.0 licence is a requirementnot Eclipse Mosquitto
  • Replacing Elasticsearch after the licence change without changing architecturenot Eclipse Mosquitto
  • Search plus analytics on one cluster rather than two systemsnot 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.

OpenSearch

  • Diverged from Elasticsearch since 7.10, so clients, plugins and features no longer map one to one
  • Operationally heavy in the way Elasticsearch is: cluster sizing, shard strategy and JVM tuning are ongoing work
  • Smaller ecosystem of third-party tooling than Elasticsearch, which most integrations still target first
  • Overkill for plain application search, where a dedicated search engine is far simpler

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

OpenSearch

Free
  • OpenSearchFree
    • Full functionality
    • Self-hosted
    • No usage limits

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 OpenSearch if

  • You need full-text search.
  • You want to start without paying.
  • You work on Linux, Docker, Kubernetes, Self-hosted.
  • You also want opensearch dashboards.
OpenSearch review

Questions people ask

Is Eclipse Mosquitto or OpenSearch better?
Neither clearly leads. Eclipse Mosquitto starts at Free and OpenSearch at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Eclipse Mosquitto or OpenSearch?
Eclipse Mosquitto starts at Free and OpenSearch at Free.
Does Eclipse Mosquitto or OpenSearch run on more platforms?
Eclipse Mosquitto runs on Linux, Windows, macOS, Docker. OpenSearch runs on Linux, Docker, Kubernetes, Self-hosted.
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 OpenSearch is typically brought in for.
What can Eclipse Mosquitto do that OpenSearch cannot?
Eclipse Mosquitto covers MQTT 5.0 support, Very small footprint, Bridging, WebSockets listener. OpenSearch covers Full-text search, OpenSearch Dashboards, Log analytics, Vector search.

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.

OpenSearch: Is OpenSearch free?

Yes, Apache 2.0 licensed under the Linux Foundation. Amazon OpenSearch Service is a paid managed option.

Eclipse Mosquitto: What licence is it?

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

OpenSearch: Why does OpenSearch exist?

Elastic moved Elasticsearch off the Apache 2.0 licence in 2021. AWS forked the last Apache-licensed version, and the project now sits under the Linux Foundation.

Eclipse Mosquitto: How many clients can it handle?

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

OpenSearch: Is OpenSearch compatible with Elasticsearch?

It was at the 7.10 fork point. Both have developed independently since, so compatibility weakens with every release and should be verified for the features you use.

Eclipse Mosquitto: Does it support MQTT 5?

Yes, along with 3.1.1 and 3.1.

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