This call returns at most 1000 file names per transaction, but it can be called repeatedly to scan through all of the file names in a bucket. Each time you call, it returns a "nextFileName" that can be used as the starting point for the next call.

There may be many file versions for the same name, but this call will return each name only once. Files that have been hidden will not be returned; to see all versions of a file, including hide markers, use b2_list_file_versions instead.

To go through all of the file names in a bucket, use a loop like this:

startFileName = null
while true:
    response = b2_list_file_names(bucketId = ..., startFileName = startFileName)
    for file in response.files:
        process_one_file_name(file)
    if response.startFileName == null:
         break
    startFileName = response.nextFileName

Prefixes and Delimiters

You can optionally specify a file name prefix, which will restrict the results to only files starting with that prefix.

Another option is to specify a delimiter (usually "/") for folder names. If found after the file name prefix, the delimiter is treated as the end of a folder name, and the folder name is returned, replacing all of the files in that folder. Each item returned is either an "upload" (a file) or a "folder" (representing one or many files).

As an example, if you have these files in your bucket:

photos/alice.jpg
photos/alfred.jpg
photos/cats/fluffy.jpg
photos/cats/mittens.jpg
photos/dogs/spot.jpg
photos/lilly.jpg

With the default prefix of "" and no delimiter, you get all of the files:

upload    photos/alice.jpg
upload    photos/alfred.jpg
upload    photos/cats/fluffy.jpg
upload    photos/cats/mittens.jpg
upload    photos/dogs/spot.jpg
upload    photos/lilly.jpg

If you use a prefix of "photos/c" you will get the same list as if you specify "photos/cats/" as the prefix:

upload    photos/cats/fluffy.jpg
upload    photos/cats/mittens.jpg

With a prefix of "" (meaning all files), and a delimiter of "/", you would get:

folder    photos/

With a prefix of "photos/", and a delimiter of "/", you would get:

upload    photos/alice.jpg
upload    photos/alfred.jpg
folder    photos/cats/
folder    photos/dogs/
upload    photos/lilly.jpg

Prefixes are parsed as literal strings, so regular expressions and wildcards cannot be used in this context. For example, a prefix of .*cats would only find a match if a file's full name starts with the literal string .*cats.

Bucket and Prefix Restrictions

When using an application key that is restricted to one bucket, and to files matching a name prefix in that bucket, you must only ask about those files. Listing files in other buckets is not allowed. Listing files that do not match the prefix is not allowed, so you must specify a prefix that is at least as restrictive as the one in the application key.

Request

Request HTTP Headers

Authorization

required

The account authorization token returned by b2_authorize_account. The token must have the listFiles capability.

Request HTTP Message Body Parameters

bucketId

required

The bucket to look for file names in. Returned by b2_list_buckets.

startFileName

optional

The first file name to return. If there is a file with this name, it will be returned in the list. If not, the first file name after this the first one after this name.

maxFileCount

optional

The maximum number of files to return from this call. The default value is 100, and the maximum is 10000. Passing in 0 means to use the default of 100.
NOTE: b2_list_file_names is a Class C transaction (see Pricing). The maximum number of files returned per transaction is 1000. If you set maxFileCount to more than 1000 and more than 1000 are returned, the call will be billed as multiple transactions, as if you had made requests in a loop asking for 1000 at a time. For example: if you set maxFileCount to 10000 and 3123 items are returned, you will be billed for 4 Class C transactions.

prefix

optional

Files returned will be limited to those with the given prefix. Defaults to the empty string, which matches all files.

delimiter

optional

Files returned will be limited to those within the top folder, or any one subfolder. Defaults to NULL. Folder names will also be returned. The delimiter character will be used to "break" file names into folders.

Response

Response HTTP Status 200

List of file names as JSON:

files

An array of objects, each one describing one file or folder. (See below.)

nextFileName

What to pass in to startFileName for the next search to continue where this one left off, or null if there are no more files. Note this this may not be the name of an actual file, but using it is guaranteed to find the next file in the bucket.

And each of the files is:

accountId

The account that owns the file.

action

One of "start", "upload", "hide", "folder", or other values added in the future. "upload" means a file that was uploaded to B2 Cloud Storage. "start" means that a large file has been started, but not finished or canceled. "hide" means a file version marking the file as hidden, so that it will not show up in b2_list_file_names. "folder" is used to indicate a virtual folder when listing files.

bucketId

The bucket that the file is in.

contentLength

The number of bytes stored in the file. Only useful when the action is "upload". Always 0 when the action is "start", "hide", or "folder".

contentSha1

The SHA1 of the bytes stored in the file as a 40-digit hex string. Large files do not have SHA1 checksums, and the value is "none". The value is null when the action is "hide" or "folder".

contentMd5

optional

The MD5 of the bytes stored in the file as a 32-digit hex string. Not all files have an MD5 checksum, so this field is optional, and set to null for files that do not have one. Large files do not have MD5 checksums, and the value is null. The value is also null when the action is "hide" or "folder".

contentType

When the action is "upload" or "start", the MIME type of the file, as specified when the file was uploaded. For "hide" action, always "application/x-bz-hide-marker". For "folder" action, always null.

fileId

The unique identifier for this version of this file. Used with b2_get_file_info, b2_download_file_by_id, and b2_delete_file_version. The value is null when for action "folder".

fileInfo

The custom information that was uploaded with the file. This is a JSON object, holding the name/value pairs that were uploaded with the file.

fileName

The name of this file, which can be used with b2_download_file_by_name.

fileRetention

The Object Lock retention settings for this file, if any.
This field is filtered based on application key capabilities; the readFileRetentions capability is required to access the value. See Object Lock for more details on response structure.
This field is omitted when the action is "hide" or "folder".

legalHold

The Object Lock legal hold status for this file, if any.
This field is filtered based on application key capabilities; the readFileLegalHolds capability is required to access the value. See Object Lock for more details on response structure.
This field is omitted when the action is "hide" or "folder".

replicationStatus

The Replication Status for this file, if any. This will show either PENDING, COMPLETED, FAILED, or REPLICA. For details see Cloud Replication
This field is omitted when the file is not part of a replication rule.

serverSideEncryption

When the file is encrypted with Server-Side Encryption, the mode ("SSE-B2" or "SSE-C") and algorithm used to encrypt the data. If the file is not encrypted with Server-Side Encryption, then both mode and algorithm will be null.
This field is omitted when the action is "hide" or "folder".

uploadTimestamp

This is a UTC time when this file was uploaded. It is a base 10 number of milliseconds since midnight, January 1, 1970 UTC. This fits in a 64 bit integer such as the type "long" in the programming language Java. It is intended to be compatible with Java's time long. For example, it can be passed directly into the java call Date.setTime(long time).
Always 0 when the action is "folder".

Response Errors

If possible the server will return a JSON error structure. Errors include:

status	code	description
400	bad_bucket_id	The requested bucket ID does not match an existing bucket.
400	bad_request	The request had the wrong fields or illegal values. The message returned with the error will describe the problem.
400	cannot_delete_non_empty_bucket	A bucket must be empty before it can be deleted. To delete this bucket, first remove all of the files in the bucket, then try the delete operation again.
400	invalid_bucket_id	Invalid bucketId: <bucketId>
400	out_of_range	maxFileCount out of range: <maxFileCount>
401	bad_auth_token	The auth token used is not valid. Call b2_authorize_account again to either get a new one, or an error message describing the problem.
401	expired_auth_token	The auth token used has expired. Call b2_authorize_account again to get a new one.
401	unauthorized	The auth token used is valid, but does not authorize this call with these parameters. The capabilities of an auth token are determined by the application key used with b2_authorize_account.
403	transaction_cap_exceeded	Transaction cap exceeded. To increase your cap, sign in to your B2 Cloud Storage account online. Then select the Caps & Alerts link in the B2 Cloud Storage section of the sidebar.
429	too_many_requests	B2 may limit API requests on a per-account basis.
503	bad_request	Timed out while iterating and skipping files

API Versions

v2: Object Lock (May 11, 2021)

Now returns fileRetention and legalHold.

v2: Server-Side Encryption (March 5, 2021)

Now returns serverSideEncryption.

v2: Remove application key workaround (Sept 13, 2018)

Listing file names will always return all of the file names you ask for. If your application key has a file name prefix restriction, and you ask for files outside that prefix, the call is unauthorized.

Now returns accountId and bucketId. Does not return size any more; use contentLength instead.

v1: Workaround for existing applications and application keys (August 9, 2018)

When using an application key with a file name prefix restriction, a request to list files will be filtered to show only files allowed by the application key.

v1: Original release (September 22, 2015)

Original release.

Sample Code

Code

curl \
    -H 'Authorization: ACCOUNT_AUTHORIZATION_TOKEN' \
    -d '{"bucketId": "BUCKET_ID"}' \
    https://apiNNN.backblazeb2.com/b2api/v2/b2_list_file_names

Output

{
  "files": [
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 7,
      "contentSha1": "dc724af18fbdd4e59189f5fe768a5f8311527050",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10904e5ca06493a1_d20180914_m223119_c002_v0001094_t0002",
      "fileInfo": {
        "src_last_modified_millis": "1536964184056"
      },
      "fileName": "testing.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-C"
      },
      "uploadTimestamp": 1536964279000
    },
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 8,
      "contentSha1": "596b29ec9afea9e461a20610d150939b9c399d93",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10076875fe98d4af_d20180914_m223128_c002_v0001108_t0050",
      "fileInfo": {
        "src_last_modified_millis": "1536964200750"
      },
      "fileName": "testing2.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-B2"
      },
      "uploadTimestamp": 1536964288000
    }
  ],
  "nextFileName": null
}

Code

import java.io.*;
import java.util.*;
import javax.json.*;
import java.net.HttpURLConnection;
import java.net.URL;

String apiUrl = ""; // Provided by b2_authorize_account
String accountAuthorizationToken = ""; // Provided by b2_authorize_account
String bucketId = "";  // The ID of the bucket you are querying
HttpURLConnection connection = null;
String postParams = "{\"bucketId\":\"" + bucketId + "\"}";
byte postData[] = postParams.getBytes(StandardCharsets.UTF_8);
try {
    URL url = new URL(apiUrl + "/b2api/v2/b2_list_file_names");
    connection = (HttpURLConnection)url.openConnection();
    connection.setRequestMethod("POST");
    connection.setRequestProperty("Authorization", accountAuthorizationToken);
    connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    connection.setRequestProperty("Charset", "UTF-8");
    connection.setRequestProperty("Content-Length", Integer.toString(postData.length));
    connection.setDoOutput(true);
    DataOutputStream writer = new DataOutputStream(connection.getOutputStream());
    writer.write(postData);
    String jsonResponse = myInputStreamReader(connection.getInputStream());
    System.out.println(jsonResponse);
} catch (Exception e) {
    e.printStackTrace();
} finally {
    connection.disconnect();
}

static public String myInputStreamReader(InputStream in) throws IOException {
    InputStreamReader reader = new InputStreamReader(in);
    StringBuilder sb = new StringBuilder();
    int c = reader.read();
    while (c != -1) {
        sb.append((char)c);
        c = reader.read();
    }
    reader.close();
    return sb.toString();
}

Output

{
  "files": [
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 7,
      "contentSha1": "dc724af18fbdd4e59189f5fe768a5f8311527050",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10904e5ca06493a1_d20180914_m223119_c002_v0001094_t0002",
      "fileInfo": {
        "src_last_modified_millis": "1536964184056"
      },
      "fileName": "testing.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-C"
      },
      "uploadTimestamp": 1536964279000
    },
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 8,
      "contentSha1": "596b29ec9afea9e461a20610d150939b9c399d93",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10076875fe98d4af_d20180914_m223128_c002_v0001108_t0050",
      "fileInfo": {
        "src_last_modified_millis": "1536964200750"
      },
      "fileName": "testing2.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-B2"
      },
      "uploadTimestamp": 1536964288000
    }
  ],
  "nextFileName": null
}

Code

import json
import urllib2

api_url = "" # Provided by b2_authorize_account
account_authorization_token = "" # Provided by b2_authorize_account
bucket_id = "" # The ID of the bucket you are querying
request = urllib2.Request(
	'%s/b2api/v2/b2_list_file_names' % api_url,
	json.dumps({ 'bucketId' : bucket_id }),
	headers = { 'Authorization': account_authorization_token }
	)
response = urllib2.urlopen(request)
response_data = json.loads(response.read())
response.close()

Output

{
  "files": [
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 7,
      "contentSha1": "dc724af18fbdd4e59189f5fe768a5f8311527050",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10904e5ca06493a1_d20180914_m223119_c002_v0001094_t0002",
      "fileInfo": {
        "src_last_modified_millis": "1536964184056"
      },
      "fileName": "testing.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-C"
      },
      "uploadTimestamp": 1536964279000
    },
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 8,
      "contentSha1": "596b29ec9afea9e461a20610d150939b9c399d93",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10076875fe98d4af_d20180914_m223128_c002_v0001108_t0050",
      "fileInfo": {
        "src_last_modified_millis": "1536964200750"
      },
      "fileName": "testing2.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-B2"
      },
      "uploadTimestamp": 1536964288000
    }
  ],
  "nextFileName": null
}

Code

import Foundation

let apiUrl = "" // Provided by b2_authorize_account
let accountAuthorizationToken = "" // Provided by b2_authorize_account
let bucketId = "" // The ID of the bucket you are querying

// Create the request
var request = URLRequest(url: URL(string: "\(apiUrl)/b2api/v2/b2_list_file_names")!)
request.httpMethod = "POST"
request.addValue(accountAuthorizationToken, forHTTPHeaderField: "Authorization")
request.httpBody = "{\"bucketId\":\"\(bucketId)\"}".data(using: .utf8)

// Create the task
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
	if let data = data {
		let json = String(data: data, encoding: .utf8)
		print("\(json!)")
	}
}

// Start the task
task.resume()

// Swift 4.1 (swiftlang-902.0.48 clang-902.0.37.1) Xcode 9.3.1 (9E501)

Output

{
  "files": [
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 7,
      "contentSha1": "dc724af18fbdd4e59189f5fe768a5f8311527050",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10904e5ca06493a1_d20180914_m223119_c002_v0001094_t0002",
      "fileInfo": {
        "src_last_modified_millis": "1536964184056"
      },
      "fileName": "testing.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-C"
      },
      "uploadTimestamp": 1536964279000
    },
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 8,
      "contentSha1": "596b29ec9afea9e461a20610d150939b9c399d93",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10076875fe98d4af_d20180914_m223128_c002_v0001108_t0050",
      "fileInfo": {
        "src_last_modified_millis": "1536964200750"
      },
      "fileName": "testing2.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-B2"
      },
      "uploadTimestamp": 1536964288000
    }
  ],
  "nextFileName": null
}

Code

require 'json'
require 'net/http'

api_url = "" # Provided by b2_authorize_account
account_authorization_token = "" # Provided by b2_authorize_account
bucket_id = "" # The ID of the bucket you are querying
uri = URI("#{api_url}/b2api/v2/b2_list_file_names")
req = Net::HTTP::Post.new(uri)
req.add_field("Authorization","#{account_authorization_token}")
req.body = "{\"bucketId\":\"#{bucket_id}\"}"
http = Net::HTTP.new(req.uri.host, req.uri.port)
http.use_ssl = true
res = http.start {|http| http.request(req)}
case res
when Net::HTTPSuccess then
    res.body
when Net::HTTPRedirection then
    fetch(res['location'], limit - 1)
else
    res.error!
end

Output

{
  "files": [
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 7,
      "contentSha1": "dc724af18fbdd4e59189f5fe768a5f8311527050",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10904e5ca06493a1_d20180914_m223119_c002_v0001094_t0002",
      "fileInfo": {
        "src_last_modified_millis": "1536964184056"
      },
      "fileName": "testing.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-C"
      },
      "uploadTimestamp": 1536964279000
    },
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 8,
      "contentSha1": "596b29ec9afea9e461a20610d150939b9c399d93",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10076875fe98d4af_d20180914_m223128_c002_v0001108_t0050",
      "fileInfo": {
        "src_last_modified_millis": "1536964200750"
      },
      "fileName": "testing2.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-B2"
      },
      "uploadTimestamp": 1536964288000
    }
  ],
  "nextFileName": null
}

Code

String apiUrl = "API_URL"; //Provided by b2_authorize_account 
String accountAuthorizationToken = "ACCOUNT_AUTHORIZATION_TOKEN"; //Provided by b2_authorize_account
String bucketId = "BUCKET_ID; //The unique bucket ID
HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(apiUrl + "/b2api/v2/b2_list_file_names");
string body = "{\"bucketId\":\"" + bucketId + "\"}";
var data = Encoding.UTF8.GetBytes(body);
webRequest.Method = "POST";
webRequest.Headers.Add("Authorization", accountAuthorizationToken);
webRequest.ContentType = "application/json; charset=utf-8";
webRequest.ContentLength = data.Length;
using (var stream = webRequest.GetRequestStream())
{
stream.Write(data, 0, data.Length);
stream.Close();
}
WebResponse response = (HttpWebResponse)webRequest.GetResponse();
var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
response.Close();
Console.WriteLine(responseString);

Output

{
  "files": [
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 7,
      "contentSha1": "dc724af18fbdd4e59189f5fe768a5f8311527050",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10904e5ca06493a1_d20180914_m223119_c002_v0001094_t0002",
      "fileInfo": {
        "src_last_modified_millis": "1536964184056"
      },
      "fileName": "testing.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-C"
      },
      "uploadTimestamp": 1536964279000
    },
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 8,
      "contentSha1": "596b29ec9afea9e461a20610d150939b9c399d93",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10076875fe98d4af_d20180914_m223128_c002_v0001108_t0050",
      "fileInfo": {
        "src_last_modified_millis": "1536964200750"
      },
      "fileName": "testing2.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-B2"
      },
      "uploadTimestamp": 1536964288000
    }
  ],
  "nextFileName": null
}

Code

$api_url = ""; // From b2_authorize_account call
$auth_token = ""; // From b2_authorize_account call
$bucket_id = "";  // The ID of the bucket

$session = curl_init($api_url .  "/b2api/v2/b2_list_file_names");

// Add post fields
$data = array("bucketId" => $bucket_id);
$post_fields = json_encode($data);
curl_setopt($session, CURLOPT_POSTFIELDS, $post_fields); 

// Add headers
$headers = array();
$headers[] = "Authorization: " . $auth_token;
curl_setopt($session, CURLOPT_HTTPHEADER, $headers); 

curl_setopt($session, CURLOPT_POST, true); // HTTP POST
curl_setopt($session, CURLOPT_RETURNTRANSFER, true);  // Receive server response
$server_output = curl_exec($session); // Let's do this!
curl_close ($session); // Clean up
echo ($server_output); // Tell me about the rabbits, George!

Output

{
  "files": [
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 7,
      "contentSha1": "dc724af18fbdd4e59189f5fe768a5f8311527050",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10904e5ca06493a1_d20180914_m223119_c002_v0001094_t0002",
      "fileInfo": {
        "src_last_modified_millis": "1536964184056"
      },
      "fileName": "testing.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-C"
      },
      "uploadTimestamp": 1536964279000
    },
    {
      "accountId": "ACCOUNT_ID",
      "action": "upload",
      "bucketId": "b2f6f21365e1d29f6c580f18",
      "contentLength": 8,
      "contentSha1": "596b29ec9afea9e461a20610d150939b9c399d93",
      "contentType": "text/plain",
      "fileId": "4_zb2f6f21365e1d29f6c580f18_f10076875fe98d4af_d20180914_m223128_c002_v0001108_t0050",
      "fileInfo": {
        "src_last_modified_millis": "1536964200750"
      },
      "fileName": "testing2.txt",
      "fileRetention": {
        "isClientAuthorizedToRead": true,
        "value": {
          "mode": null,
          "retainUntilTimestamp": null
        }
      },
      "legalHold": {
        "isClientAuthorizedToRead": true,
        "value": null
      },
      "serverSideEncryption": {
        "algorithm": "AES256",
        "mode": "SSE-B2"
      },
      "uploadTimestamp": 1536964288000
    }
  ],
  "nextFileName": null
}