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Databases · head to head

Memcached vs RabbitMQ

Memcached logo

Memcached

Databases

Distributed memory object caching system

From
Free
Rated
-
Full reviewWebsite
RabbitMQ logo

RabbitMQ

Databases

Open-source message broker supporting AMQP and other protocols

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; RabbitMQ not built for replay: once consumed, a message is gone, which is exactly what Kafka exists to change
  • They diverge on capability: Memcached covers In-memory key-value cache, RabbitMQ covers Flexible routing.

Where they differ

Only the attributes on which Memcached and RabbitMQ actually diverge.

Attributes where Memcached and RabbitMQ differ
AttributeMemcachedRabbitMQ
Pricing modelOpen source, no licence fee; managed cloud billed separatelyOpen source, no licence fee; managed services billed separately
PlatformsLinux, macOS, Windows, Docker, Self-hostedLinux, macOS, Windows, Docker, Kubernetes

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Databases).

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 RabbitMQ

  • Flexible routing
  • Multiple protocols
  • Management UI
  • Clustering and mirroring

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 RabbitMQ
  • Session storage where losing sessions on restart is acceptablenot RabbitMQ
  • Fronting an API whose responses are costly and change slowlynot RabbitMQ

RabbitMQ

  • Distributing background jobs to a pool of workers with retriesnot Memcached
  • Decoupling services that need delivery rather than a replayable historynot Memcached
  • Routing messages by pattern to different consumers from one publishernot 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

RabbitMQ

  • Not built for replay: once consumed, a message is gone, which is exactly what Kafka exists to change
  • Throughput ceilings are lower than a log-based platform under very heavy streaming loads
  • Queues that build up degrade broker performance, so consumer lag is an operational problem rather than just a backlog
  • Clustering and partition behaviour has historically been a source of hard-to-diagnose problems

Pricing, plan by plan

Memcached

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

RabbitMQ

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

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 RabbitMQ if

  • You need flexible routing.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, Docker, Kubernetes.
  • You also want multiple protocols.
RabbitMQ review

Questions people ask

Is Memcached or RabbitMQ better?
Neither clearly leads. Memcached starts at Free and RabbitMQ at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Memcached or RabbitMQ?
Memcached starts at Free and RabbitMQ at Free.
Does Memcached or RabbitMQ run on more platforms?
Memcached runs on Linux, macOS, Windows, Docker, Self-hosted. RabbitMQ runs on Linux, macOS, Windows, Docker, Kubernetes.
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 RabbitMQ is typically brought in for.
What can Memcached do that RabbitMQ cannot?
Memcached covers In-memory key-value cache, Multithreaded, Client-side sharding, Predictable memory use. RabbitMQ covers Flexible routing, Multiple protocols, Management UI, Clustering and mirroring.

Answered from the vendors’ own pages

Memcached: Is Memcached free?

Yes, open source with no licence fee.

RabbitMQ: Is RabbitMQ free?

Yes, open source with no licence fee. Broadcom sells commercial support.

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.

RabbitMQ: RabbitMQ or Kafka?

RabbitMQ is a message broker: simpler to run and better at flexible routing and work queues. Kafka is a replayable event log built for very high throughput streaming, and much heavier to operate.

Memcached: Does Memcached persist data?

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

RabbitMQ: Can RabbitMQ replay messages?

Not in the way Kafka can. Messages are removed once acknowledged, so rebuilding state from history is not the model.

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