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Networking · head to head

Eclipse Mosquitto vs Nebula

Eclipse Mosquitto logo

Eclipse Mosquitto

Networking

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

From
Free
Rated
-
Full reviewWebsite
Nebula logo

Nebula

Networking

Certificate based overlay network from Slack, with identity and firewall rules carried in the certificate

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.; Nebula the open source project has no user interface, no enrolment workflow and no revocation service, so certificate issuing, distribution and expiry become scripts you write and then have to keep working.
  • They diverge on capability: Eclipse Mosquitto covers MQTT 5.0 support, Nebula covers Certificate carried identity.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

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

Attributes where Eclipse Mosquitto and Nebula differ
AttributeEclipse MosquittoNebula
PlatformsLinux, Windows, macOS, DockerLinux, macOS, Windows, iOS, Android, FreeBSD

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

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 Nebula

  • Certificate carried identity
  • Group based host firewall
  • Lighthouse discovery
  • Noise protocol encryption
  • Unsafe routes
  • Managed option

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

Nebula

  • Flattening a network across several clouds and datacentres without VPC peering or route tablesnot Eclipse Mosquitto
  • Very large fleets where a central policy service on the connection path is unacceptablenot Eclipse Mosquitto
  • Environments that already run an internal certificate authority and want the network to use itnot Eclipse Mosquitto
  • Replacing per host iptables rules with policy written against roles that follow the hostnot 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.

Nebula

  • The open source project has no user interface, no enrolment workflow and no revocation service, so certificate issuing, distribution and expiry become scripts you write and then have to keep working.
  • Revoking a compromised host means distributing a blocklist entry to every other host and reloading them, which is a fleet wide operation rather than a click, and easy to get wrong under pressure.
  • Changing a host group membership means reissuing and redeploying its certificate, so policy changes are a deployment rather than a configuration edit.
  • There is no identity provider integration or single sign on in the open source version, so it maps well to servers and badly to a fleet of user laptops.
  • NAT traversal is best effort and hosts behind symmetric NAT need a relay configured deliberately, so connectivity failures show up as intermittent rather than immediate and are awkward to diagnose.

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

Nebula

Free
  • NebulaFree
    • Full functionality under the MIT licence
    • No host limit
    • You operate the certificate authority and lighthouses
  • Defined Networking$undefined/month
    • Hosted control plane and enrolment
    • Managed certificate lifecycle and revocation
    • Policy and DNS interface

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 Nebula if

  • You need certificate carried identity.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, iOS, Android, FreeBSD.
  • You also want group based host firewall.
Nebula review

Questions people ask

Is Eclipse Mosquitto or Nebula better?
Neither clearly leads. Eclipse Mosquitto starts at Free and Nebula at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Eclipse Mosquitto or Nebula?
Eclipse Mosquitto starts at Free and Nebula at Free.
Does Eclipse Mosquitto or Nebula run on more platforms?
Eclipse Mosquitto runs on Linux, Windows, macOS, Docker. Nebula runs on Linux, macOS, Windows, iOS, Android, FreeBSD.
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 Nebula is typically brought in for.
What can Eclipse Mosquitto do that Nebula cannot?
Eclipse Mosquitto covers MQTT 5.0 support, Very small footprint, Bridging, WebSockets listener. Nebula covers Certificate carried identity, Group based host firewall, Lighthouse discovery, Noise protocol encryption.

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.

Nebula: Does it use WireGuard?

No. Nebula predates the common WireGuard mesh tools and uses the Noise protocol framework with its own certificate format.

Eclipse Mosquitto: What licence is it?

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

Nebula: Can I run it without Defined Networking?

Yes, entirely. Defined Networking sells the control plane conveniences, not the network itself.

Eclipse Mosquitto: How many clients can it handle?

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

Nebula: How do I revoke a host?

Add its certificate fingerprint to the blocklist in the configuration of the other hosts and reload them. There is no online revocation check.

Eclipse Mosquitto: Does it support MQTT 5?

Yes, along with 3.1.1 and 3.1.

Nebula: Is it a good fit for laptops?

Less so than the identity provider based tools. There is no single sign on, so every laptop needs a certificate issued and renewed by whatever process you build.

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