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Databases · head to head

Memcached vs Eclipse Mosquitto

M

Memcached

Databases

Distributed memory object caching system

From
Free
Rated
-
Full reviewWebsite
Eclipse Mosquitto logo

Eclipse Mosquitto

Networking

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

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Memcached no persistence at all: restart a node and its cache is gone, which every design must assume; 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.
  • They diverge on capability: Memcached covers In-memory key-value cache, Eclipse Mosquitto covers MQTT 5.0 support.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

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

Attributes where Memcached and Eclipse Mosquitto differ
AttributeMemcachedEclipse Mosquitto
Pricing modelOpen source, no licence fee; managed cloud billed separatelyOpen source, no licence fee
PlatformsLinux, macOS, Windows, Docker, Self-hostedLinux, Windows, macOS, Docker
CategoryDatabasesNetworking

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 Memcached

  • In-memory key-value cache
  • Multithreaded
  • Client-side sharding
  • Predictable memory use

Only in Eclipse Mosquitto

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

What people use each for

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

Memcached

  • Caching expensive database query results to cut loadnot Eclipse Mosquitto
  • Session storage where losing sessions on restart is acceptablenot Eclipse Mosquitto
  • Fronting an API whose responses are costly and change slowlynot Eclipse Mosquitto

Eclipse Mosquitto

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

Where each one falls short

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

Memcached

  • No persistence at all: restart a node and its cache is gone, which every design must assume
  • No replication or failover, so losing a node loses that share of the cache
  • Only simple key-value, with none of the lists, sorted sets or streams Redis offers
  • Values are capped at 1MB by default, which surprises teams caching large documents

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.

Pricing, plan by plan

Memcached

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

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

Which should you pick?

Choose Memcached if

  • You need in-memory key-value cache.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, Docker, Self-hosted.
  • You also want multithreaded.
Memcached review

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

Questions people ask

Is Memcached or Eclipse Mosquitto better?
Neither clearly leads. Memcached starts at Free and Eclipse Mosquitto at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Memcached or Eclipse Mosquitto?
Memcached starts at Free and Eclipse Mosquitto at Free.
Does Memcached or Eclipse Mosquitto run on more platforms?
Memcached runs on Linux, macOS, Windows, Docker, Self-hosted. Eclipse Mosquitto runs on Linux, Windows, macOS, Docker.
Can I use Memcached for free?
Both have a free tier, so you can try either at no cost before committing.
What is Memcached best used for?
Memcached is most often used for caching expensive database query results to cut load, session storage where losing sessions on restart is acceptable, fronting an api whose responses are costly and change slowly. Of those, caching expensive database query results to cut load and session storage where losing sessions on restart is acceptable are not what Eclipse Mosquitto is typically brought in for.
What can Memcached do that Eclipse Mosquitto cannot?
Memcached covers In-memory key-value cache, Multithreaded, Client-side sharding, Predictable memory use. Eclipse Mosquitto covers MQTT 5.0 support, Very small footprint, Bridging, WebSockets listener.

Answered from the vendors’ own pages

Memcached: Is Memcached free?

Yes, open source with no licence fee.

Eclipse Mosquitto: Can Mosquitto be clustered?

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

Memcached: Memcached or Redis?

Memcached is a pure cache: simpler, multithreaded and very predictable. Redis adds persistence, replication and rich data structures, which is why it is the default choice unless you specifically want a cache and nothing more.

Eclipse Mosquitto: What licence is it?

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

Memcached: Does Memcached persist data?

No. Everything is in memory and lost on restart, by design.

Eclipse Mosquitto: How many clients can it handle?

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

Eclipse Mosquitto: Does it support MQTT 5?

Yes, along with 3.1.1 and 3.1.

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