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Databases · head to head

CosmosDB vs Valkey

CosmosDB logo

CosmosDB

Databases

Globally distributed, multi-model database service from Azure

From
Free
Rated
-
Full reviewWebsite
Valkey logo

Valkey

Databases

Open-source in-memory data store forked from Redis

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: CosmosDB autoscale provisioned throughput enforces a minimum of 1,000 RU/s, billed hourly whether or not the database is used; Valkey younger project, so its track record is short even though the codebase is not
  • They diverge on capability: CosmosDB covers Global Distribution, Valkey covers Redis-compatible.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which CosmosDB and Valkey actually diverge.

Attributes where CosmosDB and Valkey differ
AttributeCosmosDBValkey
Pricing modelusage-basedOpen source, no licence fee; managed cloud billed separately
PlatformsWeb, AzureLinux, macOS, Docker, Self-hosted
Founded1975Unknown

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Databases).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in CosmosDB

  • Global Distribution
  • Multi-model APIs
  • Elastic Scaling
  • Five Consistency Levels
  • SLA-backed Latency
  • Automatic Indexing
  • Serverless
  • Azure Functions

Only in Valkey

  • Redis-compatible
  • BSD licensed
  • Rich data structures
  • Replication and persistence

What people use each for

The jobs each tool is most often brought in to do.

CosmosDB

  • Running a globally distributed multi model database on Azurenot Valkey
  • Serving low latency reads and writes from multiple Azure regionsnot Valkey
  • Storing document, key value and graph data behind a managed servicenot Valkey

Valkey

  • Continuing on a permissively licensed in-memory store after the Redis licence changenot CosmosDB
  • Caching and session storage where a foundation-governed project is a procurement requirementnot CosmosDB
  • Migrating from Redis without rewriting application codenot CosmosDB

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

CosmosDB

  • Autoscale provisioned throughput enforces a minimum of 1,000 RU/s, billed hourly whether or not the database is used
  • Provisioned throughput is charged in every region the account is replicated to, so multi region accounts multiply the RU bill
  • Storage charges cover data, indexes and backups in each replicated region
  • Egress out of Azure and between regions is charged, though ingress is free
  • The free allowance is one account per Azure subscription, limited to 1,000 RU/s and 25 GB
  • RU/s rates vary by region and are only shown through the pricing calculator rather than a flat published rate

Valkey

  • Younger project, so its track record is short even though the codebase is not
  • Divergence from Redis grows over time, so compatibility is strongest near the fork point and weakens as both evolve
  • Ecosystem tooling and documentation still frequently assume Redis, leaving translation work

Pricing, plan by plan

CosmosDB

Free
  • Free TierFree
    • 1000 RU/s
    • 25GB storage
    • First 12 months
  • ServerlessFree
    • Pay per request
    • Auto-scaling
    • Event-driven workloads

Valkey

Free
  • ValkeyFree
    • Full functionality
    • Self-hosted
    • No usage limits

Which should you pick?

Choose CosmosDB if

  • You need global distribution.
  • You want to start without paying.
  • You work on Web, Azure.
  • You also want multi-model apis.
CosmosDB review

Choose Valkey if

  • You need redis-compatible.
  • You want to start without paying.
  • You work on Linux, macOS, Docker, Self-hosted.
  • You also want bsd licensed.
Valkey review

Questions people ask

Is CosmosDB or Valkey better?
Neither clearly leads. CosmosDB starts at Free and Valkey at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, CosmosDB or Valkey?
CosmosDB starts at Free and Valkey at Free.
Does CosmosDB or Valkey run on more platforms?
CosmosDB runs on Web, Azure. Valkey runs on Linux, macOS, Docker, Self-hosted.
Can I use CosmosDB for free?
Both have a free tier, so you can try either at no cost before committing.
What is CosmosDB best used for?
CosmosDB is most often used for running a globally distributed multi model database on azure, serving low latency reads and writes from multiple azure regions, storing document, key value and graph data behind a managed service. Of those, running a globally distributed multi model database on azure and serving low latency reads and writes from multiple azure regions are not what Valkey is typically brought in for.
What can CosmosDB do that Valkey cannot?
CosmosDB covers Global Distribution, Multi-model APIs, Elastic Scaling, Five Consistency Levels. Valkey covers Redis-compatible, BSD licensed, Rich data structures, Replication and persistence.

Answered from the vendors’ own pages

CosmosDB: Is there a free tier for Azure Cosmos DB?

Yes, Cosmos DB offers a free tier with 1,000 RU/s of throughput and 25 GB of storage per month for the lifetime of the account, available to new accounts.

Source
Valkey: Is Valkey free?

Yes, BSD-licensed open source under the Linux Foundation.

CosmosDB: How is Cosmos DB priced after the free tier?

Cosmos DB uses three billing models: provisioned throughput billed per request unit per second, vCore pricing for certain APIs, or serverless consumption pricing where you pay only for requests processed. Reserved capacity offers 20% discount for one year or 30% for three years.

Source
Valkey: Why does Valkey exist?

Redis changed its licence away from BSD in 2024. Valkey is the community fork continuing under permissive terms, backed by AWS, Google Cloud and Oracle among others.

CosmosDB: Can I change my pricing model after choosing one?

No. Once you select a compute pricing model and API, they cannot be changed. This choice is permanent for that database.

Source
Valkey: Can I switch from Redis to Valkey?

At the fork point it is drop-in compatible with existing clients and data. The further both projects move from that point, the more you should verify the specific features you use.

CosmosDB: Is there a trial period for Cosmos DB beyond the free tier?

Azure offers a 30-day free trial account for all Azure services. Additionally, Azure AI customers may be eligible for a 90-day free Cosmos DB subscription through the Azure AI Advantage program.

Source
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