Garnet

Garnet is a remote cache-store for developers building low-latency applications who want broad data APIs and control over deployment. Its persistence, recovery, and cluster capabilities extend it beyond a basic cache, but compatibility limits matter for teams moving from Redis.

Overview

Garnet is free, MIT-licensed software from Microsoft Research. It uses RESP and works with many unmodified Redis clients, including StackExchange.Redis, Jedis, Redisson, redis-py, node_redis, and go-redis. That can make it practical to try with familiar client libraries, but it is not a fully compatible Redis replacement and does not support Redis modules. Applications that rely on exact Redis behavior or modules should not assume they can switch without changes.

The self-hosted version leaves infrastructure, updates, and operations to you. That is a good fit for teams comfortable running a cache service themselves, but less attractive if you want someone else to handle its upkeep. Azure Cosmos DB Garnet Cache is a managed option that handles provisioning, scaling, patching, and monitoring; it remains in expanded Private Preview.

Key features

Data APIs and clients

Garnet covers strings, lists, hashes, sets, sorted sets, geo operations, HyperLogLog, bitmaps, ACLs, pub/sub, transactions, and Lua scripting. This range suits applications with varied key-value workloads and gives developers familiar Redis client options. Client support does not erase the compatibility caveat: check that the commands and behavior your application needs are supported.

Persistence and recovery

Garnet can support datasets larger than memory using local or cloud storage, and offers checkpointing and recovery. Those capabilities are useful when a cache needs more capacity than RAM alone or needs a recovery path. They also mean storage choices and operations are part of deployment planning rather than something the free self-hosted plan manages for you.

Clustering and extensibility

Multi-node cluster mode supports sharding, state migration, and replication, which gives teams tools for distributing data and coordinating changes across nodes. Developers can also register C# data structures and read-modify-write operations through a custom operator framework. That is a meaningful advantage for teams willing to extend the service in C#, though it makes Garnet more compelling to developers than to buyers seeking a turnkey cache.

Preview capabilities and security

Vector database support through DiskANN and range indexing through Bf-Tree are marked preview, so they are not a sound basis for a deployment that depends on settled capabilities. Garnet also supports TLS/SSL connections and RESP password-based authentication, useful security controls for service connections.

Pricing

Garnet: free. This self-hosted plan is the straightforward choice for teams that can provide infrastructure and handle updates and operations. There is no published seat or quota limit to weigh, but operating the service remains your responsibility.

Azure Cosmos DB Garnet Cache: custom pricing. It is billed per instance per hour with no licensing fees, uses per-node SKU pricing, and bills disk separately when persistence is enabled. Its managed provisioning, scaling, patching, and monitoring may suit teams seeking less operational work, but it is in expanded Private Preview.

Platforms

Garnet supports Linux, macOS, and Windows, and is self-hosted. That range offers deployment flexibility across common operating systems, while still requiring the team to run and maintain the service.

Who it's for

Garnet is best suited to developers and operations teams that want a free, self-hosted cache with RESP clients, persistence options, and cluster features. Its C# operator framework is especially relevant to developers who want to add custom data structures or operations. It is a weaker fit for teams that require Redis modules, complete Redis compatibility, or production-ready vector and range-index features.

Pros and cons

• Pro: The broad data API and documented Redis client libraries can accommodate varied workloads and familiar client stacks.
• Pro: Storage beyond memory, checkpointing, recovery, and multi-node cluster features provide options for larger or distributed deployments.
• Pro: The MIT license and free self-hosted plan avoid licensing fees.
• Con: Self-hosting means you own infrastructure, updates, and day-to-day operations.
• Con: It is not a full Redis drop-in replacement and does not support Redis modules, limiting suitability for some migrations.
• Con: Vector and range-index capabilities are preview features, not dependable choices for requirements that need established support.

Alternatives

Browse caching software if you want to compare more options. Choose Amazon ElastiCache if you want a paid cache service with an AWS Free Tier option, rather than Garnet's self-hosted operations model. Aiven for Valkey is worth considering if you want a free managed-service entry point: its Free plan is $0/month with one dedicated VM, one CPU, and 1 GB RAM, while excluding integrations and connection pooling.

Choose Memcached for free, open-source self-hosted caching without a hosted plan. Ristretto is the alternative when an in-process Go cache library is a better fit than a remote service. Choose Squid if you need free self-hosted proxy software, or Apache Traffic Server for a free self-hosted traffic-server option. cache2k is an Apache-licensed Java library available from Maven Central. Accessibility Test Framework for Android is another free option, built for Android accessibility testing rather than caching.

Verdict

Choose Garnet if you want a free, MIT-licensed cache with RESP client support, persistence, recovery, clustering, and room for C# extensions—and your team can operate it. Its broad APIs make it a capable option for developers, but Redis modules are unsupported and full Redis compatibility is not the goal. Look elsewhere if those are requirements, or if you need preview vector and range-index features to be production-ready.