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Networking · head to head

Eclipse Mosquitto vs Sigstore

Eclipse Mosquitto logo

Eclipse Mosquitto

Networking

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

From
Free
Rated
-
Full reviewWebsite
Sigstore logo

Sigstore

Cybersecurity

Free public signing and transparency infrastructure for open source artifacts

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.; Sigstore the security model depends on somebody watching the log. The documentation states that compromise of an identity provider or of Fulcio itself is detectable only if third parties monitor the transparency log, the monitoring tool is a community-tier rather than core project, and almost no consumer runs one.
  • They diverge on capability: Eclipse Mosquitto covers MQTT 5.0 support, Sigstore covers Fulcio.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

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

Attributes where Eclipse Mosquitto and Sigstore differ
AttributeEclipse MosquittoSigstore
Pricing modelOpen source, no licence feeOpen source, public instance free to use
PlatformsLinux, Windows, macOS, DockerWeb, Linux, macOS, Windows, Self-hosted
CategoryNetworkingCybersecurity

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 Sigstore

  • Fulcio
  • Rekor
  • Keyless signing
  • Multi-language clients
  • Timestamp authority
  • Neutral governance

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

Sigstore

  • Open source projects signing releases without running a certificate authoritynot Eclipse Mosquitto
  • Organisations meeting a signed-artifact requirement without buying a signing productnot Eclipse Mosquitto
  • Publishing provenance that a consumer can verify independently of younot Eclipse Mosquitto
  • Self-hosting the same components where a public log is unacceptablenot 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.

Sigstore

  • The security model depends on somebody watching the log. The documentation states that compromise of an identity provider or of Fulcio itself is detectable only if third parties monitor the transparency log, the monitoring tool is a community-tier rather than core project, and almost no consumer runs one.
  • It is a 99.5 percent objective with no service level agreement, which permits several hours of downtime a month and offers no remedy. A pipeline that signs on every build has taken a hard dependency on a free service with no contract behind it.
  • Log scale is a live engineering problem rather than a theoretical one. The active shard holds billions of entries, the log has already been sharded twice, and sharding version 1 requires stopping traffic, which is why a replacement was built.
  • Ten-minute certificates make trust depend on log availability. Verifying an older signature relies on the log entry proving it was made inside that window, so a lost or unreachable entry can render a valid artifact unverifiable.
  • Migration debt is substantial and ongoing. Version 2 of the log is generally available but not the public default, the signing client has an announced breaking release ahead, some official clients lag the new log format, and a post-quantum migration is named as the next break after that.

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

Sigstore

Free
  • Public good instanceFree
    • Free to everyone with no contract
    • 99.5 percent availability objective, not an agreement
    • 100KB cap per attestation upload
  • Self-hostedFree
    • Apache-2.0
    • Run your own Fulcio and Rekor
    • Rekor v2 available for self-hosters

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 Sigstore if

  • You need fulcio.
  • You want to start without paying.
  • You work on Web, Linux, macOS, Windows, Self-hosted.
  • You also want rekor.
Sigstore review

Questions people ask

Is Eclipse Mosquitto or Sigstore better?
Neither clearly leads. Eclipse Mosquitto starts at Free and Sigstore at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Eclipse Mosquitto or Sigstore?
Eclipse Mosquitto starts at Free and Sigstore at Free.
Does Eclipse Mosquitto or Sigstore run on more platforms?
Eclipse Mosquitto runs on Linux, Windows, macOS, Docker. Sigstore runs on Web, Linux, macOS, Windows, 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 Sigstore is typically brought in for.
What can Eclipse Mosquitto do that Sigstore cannot?
Eclipse Mosquitto covers MQTT 5.0 support, Very small footprint, Bridging, WebSockets listener. Sigstore covers Fulcio, Rekor, Keyless signing, Multi-language clients.

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.

Sigstore: Is the public instance really free?

Yes, with no contract and no paid tier. That is also the weakness: a 99.5 percent objective with no agreement, no remedy and support through Slack.

Eclipse Mosquitto: What licence is it?

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

Sigstore: Has the public log moved to Rekor v2?

No. Version 2 reached general availability in October 2025 and self-hosters can use it, but the public instance still defaults to version 1 and the project has said it will for the foreseeable future.

Eclipse Mosquitto: How many clients can it handle?

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

Sigstore: Does Sigstore make my dependencies safe?

No, and this is a category error worth avoiding. It tells you who published something. It has no knowledge of what the artifact contains or whether it is vulnerable.

Eclipse Mosquitto: Does it support MQTT 5?

Yes, along with 3.1.1 and 3.1.

Sigstore: What are the rate limits?

Not published. Only the 100KB cap per attestation upload is documented, so do not design a high-volume pipeline around assumed throughput.

Sigstore: Should we self-host it?

If a public record of every signature is unacceptable, or if a free service with no agreement cannot sit in your build path, then yes. Otherwise the public instance is what most projects use.

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