You must [generate an Access Key](https://developers.cloudflare.com/r2/api/s3/tokens/) before getting started. All examples will utilize `access_key_id` and `access_key_secret` variables which represent the **Access Key ID** and **Secret Access Key** values you generated.



JavaScript or TypeScript users may continue to use the [`@aws-sdk/client-s3`](https://www.npmjs.com/package/@aws-sdk/client-s3) npm package as per normal. You must pass in the R2 configuration credentials when instantiating your `S3` service client:

Compatibility

Client version `3.729.0` introduced a modification to the default checksum behavior from the client that is currently incompatible with R2 APIs.

To mitigate, users can use `3.726.1` or add the following to their S3Client config:

```ts
requestChecksumCalculation: "WHEN_REQUIRED",
responseChecksumValidation: "WHEN_REQUIRED",
```

```ts
import {
  S3Client,
  ListBucketsCommand,
  ListObjectsV2Command,
  GetObjectCommand,
  PutObjectCommand,
} from "@aws-sdk/client-s3";


const S3 = new S3Client({
  region: "auto",
  endpoint: `https://${ACCOUNT_ID}.r2.cloudflarestorage.com`,
  credentials: {
    accessKeyId: ACCESS_KEY_ID,
    secretAccessKey: SECRET_ACCESS_KEY,
  },
});


console.log(await S3.send(new ListBucketsCommand({})));
// {
//     '$metadata': {
//     httpStatusCode: 200,
//         requestId: undefined,
//         extendedRequestId: undefined,
//         cfId: undefined,
//         attempts: 1,
//         totalRetryDelay: 0
// },
//     Buckets: [
//     { Name: 'user-uploads', CreationDate: 2022-04-13T21:23:47.102Z },
//     { Name: 'my-bucket-name', CreationDate: 2022-05-07T02:46:49.218Z }
//     ],
//     Owner: {
//         DisplayName: '...',
//         ID: '...'
//     }
// }


console.log(
  await S3.send(new ListObjectsV2Command({ Bucket: "my-bucket-name" })),
);
// {
//     '$metadata': {
//       httpStatusCode: 200,
//       requestId: undefined,
//       extendedRequestId: undefined,
//       cfId: undefined,
//       attempts: 1,
//       totalRetryDelay: 0
//     },
//     CommonPrefixes: undefined,
//     Contents: [
//       {
//         Key: 'cat.png',
//         LastModified: 2022-05-07T02:50:45.616Z,
//         ETag: '"c4da329b38467509049e615c11b0c48a"',
//         ChecksumAlgorithm: undefined,
//         Size: 751832,
//         StorageClass: 'STANDARD',
//         Owner: undefined
//       },
//       {
//         Key: 'todos.txt',
//         LastModified: 2022-05-07T21:37:17.150Z,
//         ETag: '"29d911f495d1ba7cb3a4d7d15e63236a"',
//         ChecksumAlgorithm: undefined,
//         Size: 279,
//         StorageClass: 'STANDARD',
//         Owner: undefined
//       }
//     ],
//     ContinuationToken: undefined,
//     Delimiter: undefined,
//     EncodingType: undefined,
//     IsTruncated: false,
//     KeyCount: 8,
//     MaxKeys: 1000,
//     Name: 'my-bucket-name',
//     NextContinuationToken: undefined,
//     Prefix: undefined,
//     StartAfter: undefined
//   }
```

## Generate presigned URLs

You can also generate presigned links that can be used to share public read or write access to a bucket temporarily.

```ts
import { getSignedUrl } from "@aws-sdk/s3-request-presigner";


// Use the expiresIn property to determine how long the presigned link is valid.
console.log(
  await getSignedUrl(
    S3,
    new GetObjectCommand({ Bucket: "my-bucket-name", Key: "dog.png" }),
    { expiresIn: 3600 },
  ),
);
// https://my-bucket-name.<accountid>.r2.cloudflarestorage.com/dog.png?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential<credential>&X-Amz-Date=<timestamp>&X-Amz-Expires=3600&X-Amz-Signature=<signature>&X-Amz-SignedHeaders=host&x-id=GetObject


// You can also create links for operations such as putObject to allow temporary write access to a specific key.
console.log(
  await getSignedUrl(
    S3,
    new PutObjectCommand({ Bucket: "my-bucket-name", Key: "dog.png" }),
    { expiresIn: 3600 },
  ),
);
```

You can use the link generated by the `putObject` example to upload to the specified bucket and key, until the presigned link expires.

```sh
curl -X PUT https://my-bucket-name.<accountid>.r2.cloudflarestorage.com/dog.png?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential<credential>&X-Amz-Date=<timestamp>&X-Amz-Expires=3600&X-Amz-Signature=<signature>&X-Amz-SignedHeaders=host&x-id=PutObject -F "data=@dog.png"
```
