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Backblaze B2 Node.js Library

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This library uses promises, so all actions on a B2 instance return a promise in the following pattern

    b2.instanceFunction(arg1, arg2).then(
        successFn(response) { ... },
        errorFn(err) { ... }

Status of project

See the CHANGELOG for a history of updates.

Contributing and Suggestions for Changes and Fixes

Contributions and questions are welcome. If you are looking for something to help with, please have a look at the ISSUES or add an issue if there is something you would like to see or fix.

Make sure you use the .editorconfig in your IDE/editor when writing code.

Pull Requests should include:

  • Updated example in
  • Update existing tests, or add new tests to cover code changes

If you are adding tests, add these to /test/unit. Make sure the test is named fooTest.js and is located in a similar folder to the node module that is being tested.

Always run npm test before you commit.

Upgrading from 0.9.x to 1.0.x

For this update, we've switched the back end HTTP request library from request to axios as it has better Promise and progress support built in. However, there are a couple changes that will break your code and ruin your day. Here are the changes:

  • The Promise resolution has a different data structure. Where previously, the request response data was the root object in the promise resolution (res), this data now resides in
  • In v0.9.12, we added request progress reporting via the third parameter to then(). Because we are no longer using the same promise library, this functionality has been removed. However, progress reporting is still available by passing a callback function into the b2.method() that you're calling. See the documentation below for details.
  • In v0.9.x, b2.downloadFileById() accepted a fileId parameter as a String or Number. As of 1.0.0, the first parameter is now expected to be a plain Object of arguments.

Response Object

Each request returns an object with

status - int, html error Status





data - actual returned data from backblaze,

Basic Example

var B2 = require('backblaze-b2');
var b2 = new B2({
  accountId: '<accountId>',
  applicationKey: 'applicationKey'
async function GetBuckets() {
  try {
    await b2.authorize();
    var response = await b2.listBuckets()
  } catch (e){
    console.log('Error getting buckets:', e)

Uploading Large Files

To upload large files, you need to split the file into parts (between 5MB and 5GB) and upload each part seperately

First, you initiate the large file upload to get the fileId

var response = await this.b2.startLargeFile({bucketId: bucketID,fileName: fileName })
var fileID =

Then for each part you request an uploadUrl, and use the response to upload the part

var response = await this.b2.getUploadPartUrl({fileId: this.fileID})
var uploadURL =
var authToken =
response = await this.b2.uploadPart({
          partNumber: parNum,
          uploadUrl: uploadURL,
          uploadAuthToken: authToken,
          data: buf
// status checks etc.

Then finish the uploadUrl

var response = await this.b2.finishLargeFile({
      fileId: this.fileID,
      partSha1Array: {return sha1(buf)})


    var B2 = require('backblaze-b2');
    // All functions on the b2 instance return the response from the B2 API in the success callback
    // i.e. {})
    // create b2 object instance
    var b2 = new B2({
        accountId: 'accountId',
        applicationKey: 'applicationKey'
    // authorize with provided credentials
    b2.authorize();  // returns promise
    // create bucket
      bucketType // one of `allPublic`, `allPrivate`
    );  // returns promise
    // delete bucket
    b2.deleteBucket(bucketId);  // returns promise
    // list buckets
    b2.listBuckets();  // returns promise
    // update bucket2
    b2.updateBucket(bucketId, bucketType);  // returns promise
    // get upload url
    b2.getUploadUrl(bucketId);  // returns promise
    // upload file
        uploadUrl: 'uploadUrl',
        uploadAuthToken: 'uploadAuthToken',
        filename: 'filename',
        mime: '', // optional mime type, will default to 'b2/x-auto' if not provided
        data: 'data', // this is expecting a Buffer, not an encoded string
        hash: 'sha1-hash', // optional data hash, will use sha1(data) if not provided
        info: {
            // optional info headers, prepended with X-Bz-Info- when sent, throws error if more than 10 keys set
            // valid characters should be a-z, A-Z and '-', all other characters will cause an error to be thrown
            key1: value
            key2: value
        onUploadProgress: function(event) || null // progress monitoring
    });  // returns promise
    // list file names
        bucketId: 'bucketId',
        startFileName: 'startFileName',
        maxFileCount: 100,
        delimiter: '',
        prefix: ''
    });  // returns promise
    // list file versions
        bucketId: 'bucketId',
        startFileName: 'startFileName',
        maxFileCount: 100
    });  // returns promise
    // hide file
        bucketId: 'bucketId',
        fileName: 'fileName'
    });  // returns promise
    // get file info
    b2.getFileInfo(fileId);  // returns promise
    // get download authorization
      bucketId: 'bucketId',
      fileNamePrefix: 'fileNamePrefix',
      validDurationInSeconds: 'validDurationInSeconds', // a number from 0 to 604800
      b2ContentDisposition: 'b2ContentDisposition'
    });  // returns promise
    // download file by name
        bucketName: 'bucketName',
        fileName: 'fileName',
        onDownloadProgress: function(event) || null // progress monitoring
    });  // returns promise
    // download file by fileId
      fileId: 'fileId',
      onDownloadProgress: function(event) || null // progress monitoring
    });  // returns promise
    // delete file version
        fileId: 'fileId',
        fileName: 'fileName'
    });  // returns promise
    // start large file
      bucketId: 'bucketId',
      fileName: 'fileName'
    }) // returns promise
    // get upload part url
      fileId: 'fileId'
    }) // returns promise
    // get upload part
      partNumber: 'partNumber', // A number from 1 to 10000
      uploadUrl: 'uploadUrl',
      uploadAuthToken: 'uploadAuthToken', // comes from getUploadPartUrl();
      data: Buffer // this is expecting a Buffer not an encoded string,
      onUploadProgress: function(event) || null // progress monitoring
    }// returns promise
    // finish large file
      fileId: 'fileId',
      partSha1Array: [partSha1Array] // array of sha1 for each part
    }) // returns promise
    // cancel large file
      fileId: 'fileId'
    }) // returns promise


  • Yakov Khalinsky (@yakovkhalinsky)
  • Ivan Kalinin (@IvanKalinin) at Isolary
  • Brandon Patton (@crazyscience) at Isolary