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Networking · head to head

Eclipse Mosquitto vs QuestDB

Eclipse Mosquitto logo

Eclipse Mosquitto

Networking

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

From
Free
Rated
-
Full reviewWebsite
QuestDB logo

QuestDB

Databases

Fast open source time-series database for high throughput ingestion

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.; QuestDB open-source edition lacks high-availability, distributed architecture, and enterprise security features
  • They diverge on capability: Eclipse Mosquitto covers MQTT 5.0 support, QuestDB covers High Throughput Ingestion.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

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

Attributes where Eclipse Mosquitto and QuestDB differ
AttributeEclipse MosquittoQuestDB
Pricing modelOpen source, no licence feeopen-source
PlatformsLinux, Windows, macOS, DockerDocker, Kubernetes, Cloud (AWS, Azure, GCP)
CategoryNetworkingDatabases
FoundedUnknown2014

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 QuestDB

  • High Throughput Ingestion
  • SQL Support
  • Time-series Optimization
  • SIMD Vectorization
  • Column-oriented Storage
  • Built-in Web Console
  • InfluxDB Line Protocol
  • PostgreSQL

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

QuestDB

  • Time-series analytics ingesting up to 20M rows/second from IoT sensors or financial data feedsnot Eclipse Mosquitto
  • Real-time dashboarding with 32ms time-to-first-row latency for minute-level analyticsnot Eclipse Mosquitto
  • Applications requiring multi-tier storage (hot ingest, real-time SQL, cold Parquet archive)not 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.

QuestDB

  • Open-source edition lacks high-availability, distributed architecture, and enterprise security features
  • Enterprise edition pricing not published; requires contacting sales for custom quote
  • Ingestion limit of 20M rows/sec platform-dependent; may not scale to extreme throughput requirements

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

QuestDB

Free

No published plan breakdown. See the QuestDB review.

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 QuestDB if

  • You need high throughput ingestion.
  • You want to start without paying.
  • You work on Docker, Kubernetes, Cloud (AWS, Azure, GCP).
  • You also want sql support.
QuestDB review

Questions people ask

Is Eclipse Mosquitto or QuestDB better?
Neither clearly leads. Eclipse Mosquitto starts at Free and QuestDB at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Eclipse Mosquitto or QuestDB?
Eclipse Mosquitto starts at Free and QuestDB at Free.
Does Eclipse Mosquitto or QuestDB run on more platforms?
Eclipse Mosquitto runs on Linux, Windows, macOS, Docker. QuestDB runs on Docker, Kubernetes, Cloud (AWS, Azure, GCP).
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 QuestDB is typically brought in for.
What can Eclipse Mosquitto do that QuestDB cannot?
Eclipse Mosquitto covers MQTT 5.0 support, Very small footprint, Bridging, WebSockets listener. QuestDB covers High Throughput Ingestion, SQL Support, Time-series Optimization, SIMD Vectorization.

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.

QuestDB: How much does QuestDB Enterprise cost?

QuestDB does not publish specific pricing for the Enterprise tier. Customers must contact QuestDB via their enterprise contact form to receive a custom quote.

Source
Eclipse Mosquitto: What licence is it?

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

QuestDB: Does QuestDB offer a free version?

Yes, QuestDB Open Source is completely free and recommended for evaluation, prototyping, and pilot projects. Enterprise features, high availability, security, and dedicated support require the paid Enterprise tier.

Source
Eclipse Mosquitto: How many clients can it handle?

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

QuestDB: What deployment options does QuestDB offer?

QuestDB offers open source deployment, Enterprise deployment, and Bring Your Own Cloud (BYOC) deployment. Pricing details for BYOC and Enterprise tiers are not published and require direct contact with sales.

Source
Eclipse Mosquitto: Does it support MQTT 5?

Yes, along with 3.1.1 and 3.1.

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