Storage options guide
The Cloudflare Workers platform provides multiple storage options. This guide will inform you on which storage option is appropriate based on your project’s use case.
Available storage and persistency products include:
- KV for key-value storage.
- R2 for S3-compatible object storage use cases.
- Durable Objects for transactional, coordinated use cases
- D1 for relational, SQL-based database use cases.
- Queues for job queueing, batching and inter-Service (Worker to Worker) communication.
Applications built on the Workers platform may combine one or more storage components as they grow, scale or as requirements demand.
KV
Workers KV is an eventually consistent key-value data store that caches on the Cloudflare global network.
It is ideal for projects that require:
- High volumes of reads and/or repeated reads to the same keys.
- Per-object time-to-live (TTL).
- Distributed configuration.
To get started with KV:
- Read how KV works.
- Create a KV namespace.
- Review the KV Runtime API.
- Learn about KV Limits.
R2
R2 is S3-compatible blob storage that allows developers to store large amounts of unstructured data without egress fees associated with typical cloud storage services.
It is ideal for projects that require:
- Storage for files which are infrequently accessed.
- Large object storage (for example, gigabytes or more per object).
- Strong consistency per object.
- Asset storage for websites (refer to caching guide)
To get started with R2:
- Read the Get started guide.
- Learn about R2 Limits.
- Review the R2 Workers API.
Durable Objects
Durable Objects provide low-latency coordination and consistent storage for the Workers platform through global uniqueness and a transactional storage API.
Global Uniqueness guarantees that there will be a single instance of a Durable Object class with a given ID running at once, across the world. Requests for a Durable Object ID are routed by the Workers runtime to the Cloudflare data center that owns the Durable Object.
The transactional storage API provides strongly consistent key-value storage to the Durable Object. Each Object can only read and modify keys associated with that Object. Execution of a Durable Object is single-threaded, but multiple request events may still be processed out-of-order from how they arrived at the Object.
It is ideal for projects that require:
- Real-time collaboration (such as a chat application or a game server).
- Consistent storage.
- Data locality.
To get started with Durable Objects:
- Read the introductory blog post.
- Review the Durable Objects documentation.
- Get started with Durable Objects.
- Learn about Durable Objects Limits.
D1
D1 is Cloudflare’s native serverless database. With D1, you can create a database by importing data or defining your tables and writing your queries within a Worker or through the API.
D1 is ideal for:
- Persistent, relational storage for user data, account data, and other structured datasets.
- Use-cases that require querying across your data ad-hoc (using SQL).
- Workloads with a high ratio of reads to writes (most web applications).
To get started with D1:
- Read the documentation
- Follow the Get started guide to provision your first D1 database.
- Learn the D1 client API.
Queues
Cloudflare Queues allows developers to send and receive messages with guaranteed delivery. It integrates with Cloudflare Workers and offers at-least once delivery, message batching, and does not charge for egress bandwidth.
Queues is ideal for:
- Offloading work from a request to schedule later.
- Send data from Worker to Worker (inter-Service communication).
- Buffering or batching data before writing to upstream systems, including third-party APIs or Cloudflare R2
To get started with Queues:
Comparison
The following table highlights the primary differences and behaviours of KV, R2 and DO as primary storage mechanisms:
| Feature | KV | R2 | DO |
|---|---|---|---|
| Maximum storage per account | Unlimited1 | Unlimited | 50 GiB |
| Storage grouping name2 | Namespace | Bucket | Durable Object |
| Groups per account | 100 | 1,000 | Unlimited |
| Maximum keys per grouping | Unlimited | Unlimited | Unlimited |
| Maximum key size | 512 bytes | 1,024 bytes | 2,048 bytes |
| Maximum metadata per key | 1,024 bytes | 2,048 bytes | N/A |
| Maximum size per value | 25 MiB | 5 TiB | 128 KiB per value |
| Consistency model | Eventual | Strong | Transactional for multiple keys in a single DO |
| Cached | Always | Programmatically using the Worker Cache API or configure a custom public bucket domain. | Possible when using Cache API |
| S3-compatible API | No | Yes | No |
| TTL expiration | Object-level | Not currently available | Not automatic, but possible using alarms |
| Maximum operations per second | Unlimited cached reads | 10,000+ reads/s per bucket, 1,000+ writes/s per bucket3 | 500 - 1500 requests/second per Durable Object3 |
1 Free accounts are limited to 1 GiB.
2 A Durable Object namespace is a logical container for as many Durable Objects as you need and is backed by a class implementing the logic all those Durable Objects will share.
3 The overall throughput a single Durable Object can sustain strongly correlates to the compute and storage operations a Durable Object performs. A get() and/or put() workload may allow up to 2,000 requests/sec, whereas writing multiple values and serializing a large JSON response may only support 800 - 1,000 requests/sec. Offloading compute operations that do not rely on state within your Durable Object to the calling Worker can improve per-object throughput in many cases.
You can request adjustments to limits that conflict with your project goals by contacting Cloudflare. To request an increase to a limit, complete the Limit Increase Request Form and we will contact you with next steps.