ElastiCache: Valkey vs Redis OSS, which engine to pick
When you create a new ElastiCache cluster, AWS asks you to choose an engine. In 2026 that choice is not the even contest it looks like: the Redis OSS engine has not moved since late 2023, while Valkey carries every update AWS has shipped since. Here is what actually differs.
The Redis OSS engine on ElastiCache is a frozen 7.1
This is the fact that reframes the whole decision. Amazon ElastiCache for Redis OSS stops at version 7.1, which went GA in November 2023. AWS never brought Redis 8.x to ElastiCache. When Redis Inc dropped the BSD license for SSPLv1 in March 2024 (later adding AGPLv3 in May 2025), AWS, Google, and Oracle backed the Valkey fork instead of shipping the new-licensed Redis, and AWS put all of its forward ElastiCache engine work into Valkey. On ElastiCache, every engine version from 7.2 onward (7.2, 8.0, 8.1, 9.0, 9.1) is Valkey, not Redis OSS.
So the ElastiCache engine picker is misleading. It looks like Valkey versus a current Redis, but it is really Valkey 9.1 versus a Redis that has not been updated in over two years. Selecting Redis OSS today gives you a late-2023 engine with no upgrade path except migrating to Valkey later anyway.
Valkey vs Redis OSS on ElastiCache, side by side
| Aspect | Valkey | Redis OSS |
|---|---|---|
| Latest engine version | 9.1 (Jun 2026) | 7.1 (Nov 2023, frozen) |
| Upstream license | BSD-3-Clause | Redis 8.x is tri-licensed RSALv2 / SSPLv1 / AGPLv3 |
| Node price, cache.r7g.xlarge (us-east-1) | ~$0.350/hr | ~$0.437/hr |
| Serverless price vs Redis OSS | 33% lower | Baseline |
| Hash field TTL (HEXPIRE) | Yes (Valkey 9.0+) | No (needs 7.4+, not on ElastiCache) |
| Redis 8 vector sets (VADD/VSIM) | No | Not on ElastiCache at all |
| AWS default for new clusters | Yes | No |
| Protocol | RESP (same as Redis) | RESP |
| In-place migration path | n/a (target engine) | Upgrade to Valkey, zero downtime |
Sources: ElastiCache supported engine versions and ElastiCache pricing (node prices via Vantage), checked July 2026. Verify region pricing before procurement.
The price gap, in dollars
AWS prices the Valkey engine about 20 percent below Redis OSS on node-based clusters and about 33 percent below on ElastiCache Serverless. On node types it shows up directly: for a cache.r7g.xlarge (4 vCPU, ~26GB) in us-east-1, Redis OSS on-demand is roughly $0.437 per hour while Valkey is roughly $0.350 per hour (AWS pricing via Vantage, checked July 2026). Run a small three-node cluster (one primary, two replicas) 24x7 for a year and that is roughly $11,500 on Redis OSS versus $9,200 on Valkey, about $2,300 saved, for the newer engine.
Memcached does not get the same treatment: its node prices match Redis OSS, so on price-per-node Valkey is the cheapest of the three ElastiCache engines. The one caveat is cost-per-usable-cache, where Memcached still wins for a pure ephemeral cache that genuinely needs no replication, because a Memcached node spends all its memory on cache rather than on a replica you also pay for. See the Redis vs Memcached cost breakdown for that side of the decision.
Migrating an existing Redis OSS cluster
If you already run ElastiCache for Redis OSS, the switch is low-risk. Valkey is a wire-compatible fork of Redis 7.2.4 and speaks the same RESP protocol, so ElastiCache offers an in-place engine upgrade from Redis OSS to Valkey with no endpoint change and zero downtime. Your application connection string stays the same; only the engine underneath changes. AWS also lets you carry your existing discounted reserved-node rates across node sizes in the same family, so switching does not reset commitment pricing.
What you do not get by switching is Redis 8.x. Redis 8.0's vector sets (VADD/VSIM) and the Redis Query Engine live only on self-hosted Redis 8+ or Redis Cloud, never on ElastiCache. If your reason for staying on the Redis brand is those AI/RAG features, ElastiCache cannot deliver them on any engine; the managed path for those is Redis Cloud. If you just need a fast, durable, RESP-compatible cache on AWS, Valkey is the better-priced, better-maintained default.
FAQ
Should I choose Valkey or Redis OSS on ElastiCache in 2026?
For almost every new ElastiCache cluster, choose Valkey. It is the AWS-default engine for new deployments, speaks the same RESP protocol as Redis, runs a newer engine (Valkey 9.1 since June 2026 versus Redis OSS frozen at 7.1 from November 2023), and is priced about 20 percent lower per node than the Redis OSS engine. The only reason to select Redis OSS on ElastiCache is a hard requirement to stay on Redis 7.1 semantics; even then you get no forward engine updates, because AWS never brought Redis 8.x to ElastiCache.
What is the latest Redis OSS version on ElastiCache?
Redis OSS on ElastiCache tops out at version 7.1, which went GA in November 2023. AWS did not ship Redis 8.x on ElastiCache: when Redis relicensed under SSPL and later AGPLv3, AWS put all forward engine work into Valkey instead. On ElastiCache, every engine version from 7.2 upward is Valkey, not Redis OSS. Picking the Redis OSS engine today means freezing on a late-2023 release with no upgrade path other than migrating to Valkey.
Is Valkey cheaper than Redis OSS on ElastiCache?
Yes. AWS prices the Valkey engine about 20 percent lower than Redis OSS on node-based (self-designed) clusters and about 33 percent lower on ElastiCache Serverless. For a cache.r7g.xlarge node in us-east-1 that is roughly $0.350 per hour on Valkey versus roughly $0.437 per hour on Redis OSS on-demand (AWS pricing via Vantage, checked July 2026). Memcached gets no equivalent discount and is priced the same as Redis OSS per node.
Can I migrate from ElastiCache Redis OSS to Valkey without downtime?
Yes. Because Valkey is a wire-compatible fork of Redis 7.2.4 and speaks the same RESP protocol, ElastiCache supports an in-place engine upgrade from Redis OSS to Valkey with no endpoint change and zero downtime. AWS also lets you keep your existing discounted reserved-node rates across node sizes in the same family when you switch, so the migration does not reset your commitment pricing.
Does ElastiCache Redis support vector sets or Redis 8 features?
No. Redis 8.0's vector sets (VADD/VSIM) and the Redis Query Engine are only available on self-hosted Redis 8+ or Redis Cloud, not on ElastiCache, because ElastiCache never shipped Redis 8.x. If you need those AI/RAG features as a managed service on AWS, ElastiCache is not the path; Redis Cloud (available via AWS Marketplace) is. The Valkey engine on ElastiCache does have hash field TTL (HEXPIRE, added in Valkey 9.0) but does not implement vector sets.