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Memcached
What it is
Memcached is a free, self-hosted cache that keeps small pieces of data in memory to reduce database work for dynamic web applications. It can store strings, objects, and results from database calls, API calls, or page rendering. Clients use a key-based hash to choose a server; servers then operate independently, without synchronizing or replicating data. Cached items can be set to expire, and the default eviction policy removes the least recently used items. The project describes Memcached as a developer tool, not code acceleration software or database middleware, and says its API is available for most popular languages. It supports Linux, macOS, API use, and self-hosted deployment. Installation instructions and a source tarball are provided, with package prerequisites for Debian/Ubuntu and Red Hat/CentOS. TLS authentication and encryption are available in version 1.5.13 and later when built with TLS and used with a compatible client. Optional extstore shifts values to flash storage while keeping keys and the hash table in memory; it requires version 1.6.0 or newer.
For and against
For
- Free and open source.
- Caches database, API, and page-rendering results.
- Expiration and least-recently-used eviction are supported.
- API available for most popular languages.
Against
- Servers do not synchronize or replicate data.
- SASL authentication does not encrypt communications.
- Extstore requires flash storage, not rotational media.
- Items have a cited 1 MB size limit.
The verdict
Memcached offers a focused in-memory caching layer with independent servers and configurable expiration. Its server model and item-size limit are important considerations when deciding whether it fits a particular application.
Who it suits
Memcached suits developers who need an in-memory cache for database, API, or page-rendering results. It is aimed at self-hosted use and is available for Linux and macOS.
Plans and prices
Memcached
Self-hosted software · no hosted plan or price listed
Read 30 Sep 2026 · memcached.org
On the record
- Cached data
- It stores small chunks of arbitrary data, such as strings and objects, including results from database calls, API calls, or page rendering.memcached.org · read 30 Sep 2026
- Cluster model
- Clients use a key-based hashing algorithm to select a server, while servers operate independently without synchronization or replication.docs.memcached.org · read 30 Sep 2026
- Developer audience
- The documentation describes Memcached as a developer tool and says it is not code acceleration software or database middleware.docs.memcached.org · read 30 Sep 2026
- Expiration and eviction
- Items can expire after a specified time, and the default eviction policy is least recently used (LRU).docs.memcached.org · read 30 Sep 2026
- Flash storage
- The optional extstore feature moves values to external storage while keeping keys and the hash table in memory, and requires Memcached 1.6.0 or newer.docs.memcached.org · read 30 Sep 2026
- Flash storage limit
- Extstore requires flash storage rather than rotational media, and a Memcached restart effectively empties its flash data.docs.memcached.org · read 30 Sep 2026
- Installation
- The downloads page provides a source tarball and installation instructions, including package prerequisites for Debian/Ubuntu and Red Hat/CentOS.memcached.org · read 30 Sep 2026
- Item size limit
- The use cases documentation cites a 1 MB item-size limit.docs.memcached.org · read 30 Sep 2026
- Language support
- The maker says its API is available for most popular languages.memcached.org · read 30 Sep 2026
- Origin
- Memcached was originally developed by Brad Fitzpatrick for LiveJournal in 2003.memcached.org · read 30 Sep 2026
- Performance
- The documentation says queries on slow machines should run well under 1 ms and high-end servers can serve millions of keys per second.docs.memcached.org · read 30 Sep 2026
- Purpose
- Memcached is a distributed in-memory key-value cache intended to speed up dynamic web applications by reducing database load.memcached.org · read 30 Sep 2026
- SASL security
- SASL can authenticate clients but does not encrypt communications, and the documentation says it is not suitable for use over the internet.docs.memcached.org · read 30 Sep 2026
- Support
- The project directs users to its Discord chat, documentation, and mailing list for questions, and points to Cache Forge for business support.memcached.org · read 30 Sep 2026
- TLS security
- Memcached 1.5.13 and later supports authentication and encryption via TLS when built with TLS enabled and used with a TLS-capable client.docs.memcached.org · read 30 Sep 2026
