Semantic Coherence: Memcached – Signal Evidence & AI Readability

[H3] What is Memcached?
Free & open source, high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.
Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page
rendering.
Memcached is simple yet powerful. Its simple design promotes quick deployment, ease of development, and solves many problems facing large data caches. Its API is available for most popular languages.

[H3] Supported by

[IMG: Netflix]

[H3] Download Memcached
The latest stable memcached release is
v1.6.42
release notes
(2026-5-18)

[IMG: Tar.Gz Download]
tar.gz

Source and Development

[H2] Quick Example

[H3] Cache Results

function get_foo(foo_id)
foo = memcached_get("foo:" . foo_id)
return foo if defined foo
foo = fetch_foo_from_database(foo_id)
memcached_set("foo:" . foo_id, foo)
return foo
end

[H3] Play with telnet

$ telnet localhost 11211
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
get foo
VALUE foo 0 2
hi
END
stats
STAT pid 8861
(etc)

[H2] Got a Question?

[H3] Chat
If you are curious about something, feel free to ask
on the support chats -
join the Discord Chat

[H3] Documentation

Many common questions are answered at the
Documentation Site.

[H3] Email
Please feel free to bug us on the
memcached mailing list.

Interested in business support, or sponsoring memcached's development?
Cache Forge

[H2] About Memcached
memcached is a high-performance, distributed memory object caching
system, generic in nature, but originally intended for use in speeding
up dynamic web applications by alleviating database load.
You can think of it as a short-term memory for your applications.
[H2] What it Does
[IMG: usage]
memcached allows you to take memory from parts of your system where
you have more than you need and make it accessible to areas where
you have less than you need.
memcached also allows you to make better use of your memory. If you
consider the diagram to the right, you can see two deployment
scenarios:
Each node is completely independent (top).
Each node can make use of memory from other nodes (bottom).
The first scenario illustrates the classic deployment strategy,
however you'll find that it's both wasteful in the sense that the
total cache size is a fraction of the actual capacity of your web
farm, but also in the amount of effort required to keep the
cache consistent across all of those nodes.
With memcached, you can see that all of the servers are looking into
the same virtual pool of memory. This means that a given item is
always stored and always retrieved from the same location in your
entire web cluster.
Also, as the demand for your application grows
to the point where you need to have more servers, it generally also
grows in terms of the data that must be regularly accessed. A
deployment strategy where these two aspects of your system scale
together just makes sense.
The illustration to the right only shows two web servers for
simplicity, but the property remains the same as the number
increases. If you had fifty web servers, you'd still have a usable
cache size of 64MB in the first example, but in the second, you'd
have 3.2GB of usable cache.
Of course, you aren't required to use your web server's memory for
cache. Many memcached users have dedicated machines that are built
to only be memcached servers.
[H3] Origin
Memcached was originally developed by Brad Fitzpatrick for
LiveJournal in 2003.
[H3] Contributors

dormando (1138)

Dustin Sallings (214)

Brad Fitzpatrick (164)

Trond Norbye (130)

Paul Lindner (58)

Toru Maesaka (34)

Steven Grimm (25)

David Carlier (23)

Kevin Lin (17)

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Anatoly Vorobey (15)

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Steve Yen (15)

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Fei Hu (9)

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Bujna, Igor (8)

Kanak Kshetri (7)

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Peter (Stig) Edwards (6)

Steve Wills (6)

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[H2] Downloads
[H3] Latest stable
memcached-1.6.42.tar.gz
(2026-5-18)
(release notes)
(sha1: de453f58745238c70091fe243549c406aabdc3c5)
[H3] Older releases
Full list of
releases

[H2] Installation
Debian/Ubuntu: apt-get install libevent-dev
Redhat/Centos: yum install libevent-devel

wget http://memcached.org/latest
tar -zxvf memcached-1.x.x.tar.gz
cd memcached-1.x.x
./configure && make && make test && sudo make install

See the wiki
for further information

Official blog posts about the memcached ecosystem

May 22 2026 - How Long Does That Response Take... For Real

March 27 2024 - Introduction: Memcached Proxy

February 23 2020 - Paper Review: MemC3

May 8 2019 - The Volatile Benefit of Persistent Memory: Part Two

April 30 2019 - The Volatile Benefit of Persistent Memory

February 4 2019 - Caching beyond RAM: Riding the cliff

October 15 2018 - Replacing the cache replacement algorithm in memcached

August 15 2018 - Extstore In The Cloud

June 12 2018 - Caching beyond RAM: the case for NVMe