Chunked upload with SDKs

The Box SDKs include convenience methods that run a whole for you. They create the upload session, upload the file in parts, and commit the session.

Upload a new file

To upload a new file to a folder, call the convenience method for new files with the file stream, file name, file size in bytes, and parent folder ID.

await client.chunkedUploads.uploadBigFile(
  fileStream,
  fileName,
  fileSize,
  parentFolderId,
);

client.chunked_uploads.upload_big_file(
    file_stream, file_name, file_size, parent_folder_id
)

await client.ChunkedUploads.UploadBigFileAsync(file: fileStream, fileName: fileName, fileSize: fileSize, parentFolderId: parentFolderId);

try await client.chunkedUploads.uploadBigFile(file: fileStream, fileName: fileName, fileSize: fileSize, parentFolderId: parentFolderId)

client.getChunkedUploads().uploadBigFile(fileStream, fileName, fileSize, parentFolderId)

The method returns the new file.

Upload a new file version

To upload a new version of an existing file, call the convenience method for file versions with the file ID, file stream, and file size in bytes. You can also pass a new file name. Before it uploads each part, the method from the previous version of the file and skips it if so. It then commits the session with both the uploaded parts and the parts Box reused.

await client.chunkedUploads.uploadBigFileVersion(
  fileId,
  fileStream,
  fileSize,
  fileName,
);

client.chunked_uploads.upload_big_file_version(
    file_id, file_stream, file_size, file_name=file_name
)

await client.ChunkedUploads.UploadBigFileVersionAsync(fileId: fileId, file: fileStream, fileSize: fileSize, fileName: fileName);

try await client.chunkedUploads.uploadBigFileVersion(fileId: fileId, file: fileStream, fileSize: fileSize, fileName: fileName)

client.getChunkedUploads().uploadBigFileVersion(fileId, fileStream, fileSize, fileName)

The method returns the updated file, or an empty result when the returns 202 Accepted. The convenience method for file versions is available in the following SDK versions:

SDK	Minimum version	Minimum combined version
	`v10.16.0`
	`v10.16.0`
	`v10.18.0`
	`10.16.0`
	`v10.18.0`

The combined versions include both the manually maintained and the generated SDK packages. In these versions, call the method from the generated package. For details, see .

If your application creates an upload session for an existing file and uploads each part itself, it uploads every part. Switch to the convenience method for file versions to skip the parts Box already stores.

For a complete Python example with preflight checks and name conflict handling, see .

Last modified on November 12, 2026

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Chunked upload with SDKs

Upload a new file

Upload a new file version