Garnet

Garnet is a free, MIT-licensed remote cache-store from Microsoft Research for developers building low-latency applications and willing to operate their own infrastructure. It is strongest for teams that want broad data APIs, persistence, clustering, and familiar Redis clients without requiring exact Redis parity.

Overview

Garnet speaks RESP and works with many unmodified Redis clients, including StackExchange.Redis. That can make it practical to use with existing client libraries, but it is not a fully compatible Redis replacement and does not support Redis modules. Teams whose applications depend on module support or precise Redis behavior should look elsewhere.

The self-hosted software gives teams control over deployment, but they remain responsible for infrastructure, updates, and operations. Azure Cosmos DB Garnet Cache offers a managed alternative that takes on provisioning, scaling, patching, and monitoring; it is in expanded Private Preview.

Key features

Broad data APIs and clients

Garnet supports strings, lists, hashes, sets, sorted sets, geo operations, HyperLogLog, bitmaps, ACLs, pub/sub, transactions, and Lua scripting. Its documented client libraries include StackExchange.Redis, Jedis, Redisson, redis-py, node_redis, and go-redis. This range suits applications that need varied key-value data structures and client choices, though the compatibility caveat still matters for workloads built around Redis-specific behavior.

Storage and cluster operations

Datasets can exceed memory by using local or cloud storage, with checkpointing and recovery for persistence. Multi-node cluster mode adds sharding, state migration, and replication. These capabilities give teams options for larger datasets and distributed deployments, but they do not remove the operational work of running the self-hosted plan.

Extensibility, security, and preview features

A custom operator framework lets developers register C# data structures and read-modify-write operations, making Garnet more adaptable to application-specific needs. TLS/SSL connections and RESP password authentication provide connection security options. Vector database support using DiskANN and range indexing with Bf-Tree are marked preview, so they are a poor foundation for requirements that need settled production features.

Pricing

Garnet

The self-hosted Garnet plan costs nothing. There is no software license charge, but teams must provide and manage infrastructure, updates, and operations. It fits developers and organizations prepared to take on that work; readers seeking a managed cache should consider the Azure service instead.

Azure Cosmos DB Garnet Cache

This managed service has custom pricing: it is billed per instance per hour with no licensing fees, using per-node SKU pricing. Disk is billed separately when persistence is enabled. It handles infrastructure provisioning, scaling, patching, and monitoring, which may suit teams that want less operational overhead, but it remains in expanded Private Preview.

Platforms

Garnet is available for Linux, macOS, and Windows, with self-hosted deployment. Its documented client libraries span StackExchange.Redis, Jedis, Redisson, redis-py, node_redis, and go-redis, offering options across several development ecosystems.

Who it's for

Garnet is a fit for teams that need a low-latency remote cache, broad data structures, persistence or multi-node clustering, and the ability to run their own infrastructure. Developers with application-specific data needs may also value the C# operator framework. It is not a strong match for workloads that require Redis modules, full Redis compatibility, or production-ready vector and range-index features.

Pros and cons

Pros

• Free, MIT-licensed self-hosted software avoids a licensing fee while leaving teams control over deployment.
• Broad data APIs, Lua scripting, transactions, and support for familiar Redis client libraries cover a wide range of cache workloads.
• Storage beyond memory, checkpointing, recovery, and multi-node cluster features support larger and distributed deployments.
• The managed Azure service automates provisioning, scaling, patching, and monitoring for teams seeking less infrastructure work.

Cons

• Self-hosted users must manage infrastructure, updates, and operations themselves.
• Incomplete Redis compatibility and no Redis module support rule it out for some existing Redis workloads.
• Disk charges apply separately to the managed service when persistence is enabled, and its expanded Private Preview status may not fit every deployment need.
• Vector database and range index support are preview features, not settled choices for production-critical requirements.

Alternatives

Explore caching software for more options. Consider Amazon ElastiCache if you want a paid alternative with a free AWS tier. Aiven for Valkey is worth considering if you prefer a freemium service with a free plan and trial; its free plan provides one dedicated VM, one CPU, and 1 GB RAM, without integrations or connection pooling. Choose Memcached for free, open-source, self-hosted cache software. Ristretto is an open-source Go in-process cache, while Squid is free, self-hosted proxy software. Alibaba Cloud Tair offers a 30-day trial of its Redis OSS-compatible Open Source Edition for new users, with 1 GB RAM. Consider Ehcache for an open-source, Apache 2.0-licensed alternative. Accessibility Test Framework for Android is another free option.

Verdict

Choose Garnet if you want a free, extensible cache with broad data APIs, persistence, and clustering, and can own the self-hosting work. Its main reason to choose it is that capability range without a licensing fee; look elsewhere if your application needs complete Redis compatibility or depends on Redis modules.