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Important: This API works only on ChromeOS. DescriptionUse the chrome.fileSystemProvider API to create file systems, that can be accessible from the file manager on Chrome OS.
fileSystemProvider
You must declare the "fileSystemProvider" permission and section in the extension manifest to use the File System Provider API. For example:
{
"name": "My extension",
...
"permissions": [
"fileSystemProvider"
],
...
"file_system_provider_capabilities": {
"configurable": true,
"watchable": false,
"multiple_mounts": true,
"source": "network"
},
...
}
The file_system_provider section must be declared as follows:
configurable (boolean) - optional
multiple_mounts (boolean) - optional
watchable (boolean) - optional
source (enum of "file", "device", or "network") - required
Files app uses above information in order to render related UI elements appropriately. For example, if configurable is set to true, then a menu item for configuring volumes will be rendered. Similarly, if multiple_mounts is set to true, then Files app will allow to add more than one mount points from the UI. If watchable is false, then a refresh button will be rendered. Note, that if possible you should add support for watchers, so changes on the file system can be reflected immediately and automatically.
File System Provider API allows extensions to support virtual file systems, which are available in the file manager on ChromeOS. Use cases include decompressing archives and accessing files in a cloud service other than Drive.
Mounting file systemsProviding extensions can either provide file system contents from an external source (such as a remote server or a USB device), or using a local file (such as an archive) as its input.
In order to write file systems which are file handlers (source is "file") the provider must be a packaged app, as the onLaunched event is not available to extensions.
If the source is network or a device, then the file system should be mounted when onMountRequested event is called.
Source of the file system data Entry point"file" Available to packaged apps only. "device" or "network" onMountRequested Configuring file systems
Provided file systems once mounted can be configured via the onConfigureRequested event. It's especially useful for file systems which provide contents via network in order to set proper credentials. Handling this event is optional.
Life cycleProvided file systems once mounted are remembered by Chrome and remounted automatically after reboot or restart. Hence, once a file system is mounted by a providing extension, it will stay until either the extension is unloaded, or the extension calls the unmount method.
Types PropertiesThe identifier of the file system related to this operation.
operationRequestId
number
An ID of the request to be aborted.
The unique identifier of this request.
The identifier of the action. Any string or CommonActionId for common actions.
The title of the action. It may be ignored for common actions.
The path of the entry to be observed.
The identifier of the file system related to this operation.
Whether observing should include all child entries recursively. It can be true for directories only.
The unique identifier of this request.
The type of the change which happened to the entry.
Information relating to the file if backed by a cloud file system.
The path of the changed entry.
Type of a change detected on the observed directory.
CloseFileRequestedOptions PropertiesThe identifier of the file system related to this operation.
A request ID used to open the file.
The unique identifier of this request.
versionTag
string optional
A tag that represents the version of the file.
The provider's identifier for the given file/directory.
Identifier for the cloud storage provider (e.g. 'drive.google.com').
List of common actions. "SHARE" is for sharing files with others. "SAVE_FOR_OFFLINE" for pinning (saving for offline access). "OFFLINE_NOT_NECESSARY" for notifying that the file doesn't need to be stored for offline access anymore. Used by onGetActionsRequested and onExecuteActionRequested.
"SAVE_FOR_OFFLINE"
"OFFLINE_NOT_NECESSARY"
"SHARE"
The identifier of the file system to be configured.
The unique identifier of this request.
The identifier of the file system related to this operation.
The unique identifier of this request.
The source path of the entry to be copied.
The destination path for the copy operation.
The path of the directory to be created.
The identifier of the file system related to this operation.
Whether the operation is recursive (for directories only).
The unique identifier of this request.
The path of the file to be created.
The identifier of the file system related to this operation.
The unique identifier of this request.
The path of the entry to be deleted.
The identifier of the file system related to this operation.
Whether the operation is recursive (for directories only).
The unique identifier of this request.
Information that identifies a specific file in the underlying cloud file system. Must be provided if requested in options and the file is backed by cloud storage.
Cloud storage representation of this entry. Must be provided if requested in options and the file is backed by cloud storage. For local files not backed by cloud storage, it should be undefined when requested.
isDirectory
boolean optional
True if it is a directory. Must be provided if requested in options.
Mime type for the entry. Always optional, but should be provided if requested in options.
modificationTime
Date optional
The last modified time of this entry. Must be provided if requested in options.
Name of this entry (not full path name). Must not contain '/'. For root it must be empty. Must be provided if requested in options.
File size in bytes. Must be provided if requested in options.
thumbnail
string optional
Thumbnail image as a data URI in either PNG, JPEG or WEBP format, at most 32 KB in size. Optional, but can be provided only when explicitly requested by the onGetMetadataRequested event.
The identifier of the action to be executed.
The set of paths of the entries to be used for the action.
The identifier of the file system related to this operation.
The unique identifier of this request.
A human-readable name for the file system.
The identifier of the file system.
List of currently opened files.
The maximum number of files that can be opened at once. If 0, then not limited.
supportsNotifyTag
boolean optional
Whether the file system supports the tag field for observing directories.
List of watchers.
Whether the file system supports operations which may change contents of the file system (such as creating, deleting or writing to files).
List of paths of entries for the list of actions.
The identifier of the file system related to this operation.
The unique identifier of this request.
Set to true if cloudFileInfo value is requested.
Set to true if cloudIdentifier value is requested.
The path of the entry to fetch metadata about.
The identifier of the file system related to this operation.
Set to true if is_directory value is requested.
Set to true if mimeType value is requested.
Set to true if modificationTime value is requested.
Set to true if name value is requested.
The unique identifier of this request.
Set to true if size value is requested.
Set to true if thumbnail value is requested.
A human-readable name for the file system.
The string indentifier of the file system. Must be unique per each extension.
openedFilesLimit
number optional
The maximum number of files that can be opened at once. If not specified, or 0, then not limited.
persistent
boolean optional
Whether the framework should resume the file system at the next sign-in session. True by default.
supportsNotifyTag
boolean optional
Whether the file system supports the tag field for observed directories.
writable
boolean optional
Whether the file system supports operations which may change contents of the file system (such as creating, deleting or writing to files).
The identifier of the file system related to this operation.
The unique identifier of this request.
The source path of the entry to be moved into a new place.
The destination path for the copy operation.
The type of the change which happened to the observed entry. If it is DELETED, then the observed entry will be automatically removed from the list of observed entries.
List of changes to entries within the observed directory (including the entry itself)
The identifier of the file system related to this change.
The path of the observed entry.
Mode of the observed entry.
Tag for the notification. Required if the file system was mounted with the supportsNotifyTag option. Note, that this flag is necessary to provide notifications about changes which changed even when the system was shutdown.
The path of the opened file.
Whether the file was opened for reading or writing.
A request ID to be be used by consecutive read/write and close requests.
The path of the file to be opened.
The identifier of the file system related to this operation.
Whether the file will be used for reading or writing.
A request ID which will be used by consecutive read/write and close requests.
Error codes used by providing extensions in response to requests as well as in case of errors when calling methods of the API. For success, "OK" must be used.
"OK"
"FAILED"
"IN_USE"
"EXISTS"
"NOT_FOUND"
"ACCESS_DENIED"
"TOO_MANY_OPENED"
"NO_MEMORY"
"NO_SPACE"
"NOT_A_DIRECTORY"
"INVALID_OPERATION"
"SECURITY"
"ABORT"
"NOT_A_FILE"
"NOT_EMPTY"
"INVALID_URL"
"IO"
The path of the directory which contents are requested.
The identifier of the file system related to this operation.
Set to true if is_directory value is requested.
Set to true if mimeType value is requested.
Set to true if modificationTime value is requested.
Set to true if name value is requested.
The unique identifier of this request.
Set to true if size value is requested.
Set to true if thumbnail value is requested.
The identifier of the file system related to this operation.
Number of bytes to be returned.
Position in the file (in bytes) to start reading from.
A request ID used to open the file.
The unique identifier of this request.
The path of the watched entry.
The identifier of the file system related to this operation.
Mode of the watcher.
The unique identifier of this request.
The path of the file to be truncated.
The identifier of the file system related to this operation.
Number of bytes to be retained after the operation completes.
The unique identifier of this request.
The identifier of the file system to be unmounted.
The identifier of the file system to be unmounted.
The unique identifier of this request.
The path of the entry being observed.
Tag used by the last notification for the watcher.
Whether watching should include all child entries recursively. It can be true for directories only.
Buffer of bytes to be written to the file.
The identifier of the file system related to this operation.
Position in the file (in bytes) to start writing the bytes from.
A request ID used to open the file.
The unique identifier of this request.
chrome.fileSystemProvider.get(
fileSystemId: string,
): Promise<FileSystemInfo>
Returns information about a file system with the passed fileSystemId.
chrome.fileSystemProvider.getAll(): Promise<FileSystemInfo[]>
Returns all file systems mounted by the extension.
mount()chrome.fileSystemProvider.mount(
options: MountOptions,
): Promise<void>
Mounts a file system with the given fileSystemId and displayName. displayName will be shown in the left panel of the Files app. displayName can contain any characters including '/', but cannot be an empty string. displayName must be descriptive but doesn't have to be unique. The fileSystemId must not be an empty string.
Depending on the type of the file system being mounted, the source option must be set appropriately.
In case of an error, runtime.lastError will be set with a corresponding error code.
chrome.fileSystemProvider.notify(
options: NotifyOptions,
): Promise<void>
Notifies about changes in the watched directory at observedPath in recursive mode. If the file system is mounted with supportsNotifyTag, then tag must be provided, and all changes since the last notification always reported, even if the system was shutdown. The last tag can be obtained with getAll.
To use, the file_system_provider.notify manifest option must be set to true.
Value of tag can be any string which is unique per call, so it's possible to identify the last registered notification. Eg. if the providing extension starts after a reboot, and the last registered notification's tag is equal to "123", then it should call notify for all changes which happened since the change tagged as "123". It cannot be an empty string.
Not all providers are able to provide a tag, but if the file system has a changelog, then the tag can be eg. a change number, or a revision number.
Note that if a parent directory is removed, then all descendant entries are also removed, and if they are watched, then the API must be notified about the fact. Also, if a directory is renamed, then all descendant entries are in fact removed, as there is no entry under their original paths anymore.
In case of an error, runtime.lastError will be set will a corresponding error code.
chrome.fileSystemProvider.unmount(
options: UnmountOptions,
): Promise<void>
Unmounts a file system with the given fileSystemId. It must be called after onUnmountRequested is invoked. Also, the providing extension can decide to perform unmounting if not requested (eg. in case of lost connection, or a file error).
In case of an error, runtime.lastError will be set with a corresponding error code.
chrome.fileSystemProvider.onAbortRequested.addListener(
callback: function,
)
Raised when aborting an operation with operationRequestId is requested. The operation executed with operationRequestId must be immediately stopped and successCallback of this abort request executed. If aborting fails, then errorCallback must be called. Note, that callbacks of the aborted operation must not be called, as they will be ignored. Despite calling errorCallback, the request may be forcibly aborted.
The callback parameter looks like:
(options: AbortRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onAddWatcherRequested.addListener(
callback: function,
)
Raised when setting a new directory watcher is requested. If an error occurs, then errorCallback must be called.
The callback parameter looks like:
(options: AddWatcherRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onCloseFileRequested.addListener(
callback: function,
)
Raised when opening a file previously opened with openRequestId is requested to be closed.
The callback parameter looks like:
(options: CloseFileRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onConfigureRequested.addListener(
callback: function,
)
Raised when showing a configuration dialog for fileSystemId is requested. If it's handled, the file_system_provider.configurable manfiest option must be set to true.
The callback parameter looks like:
(options: ConfigureRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onCopyEntryRequested.addListener(
callback: function,
)
Raised when copying an entry (recursively if a directory) is requested. If an error occurs, then errorCallback must be called.
The callback parameter looks like:
(options: CopyEntryRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onCreateDirectoryRequested.addListener(
callback: function,
)
Raised when creating a directory is requested. The operation must fail with the EXISTS error if the target directory already exists. If recursive is true, then all of the missing directories on the directory path must be created.
The callback parameter looks like:
(options: CreateDirectoryRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onCreateFileRequested.addListener(
callback: function,
)
Raised when creating a file is requested. If the file already exists, then errorCallback must be called with the "EXISTS" error code.
The callback parameter looks like:
(options: CreateFileRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onDeleteEntryRequested.addListener(
callback: function,
)
Raised when deleting an entry is requested. If recursive is true, and the entry is a directory, then all of the entries inside must be recursively deleted as well.
The callback parameter looks like:
(options: DeleteEntryRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onExecuteActionRequested.addListener(
callback: function,
)
Raised when executing an action for a set of files or directories is\ requested. After the action is completed, successCallback must be called. On error, errorCallback must be called.
The callback parameter looks like:
(options: ExecuteActionRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onGetActionsRequested.addListener(
callback: function,
)
Raised when a list of actions for a set of files or directories at entryPaths is requested. All of the returned actions must be applicable to each entry. If there are no such actions, an empty array should be returned. The actions must be returned with the successCallback call. In case of an error, errorCallback must be called.
The callback parameter looks like:
(options: GetActionsRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
(actions: Action[]) => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onGetMetadataRequested.addListener(
callback: function,
)
Raised when metadata of a file or a directory at entryPath is requested. The metadata must be returned with the successCallback call. In case of an error, errorCallback must be called.
The callback parameter looks like:
(options: GetMetadataRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
(metadata: EntryMetadata) => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onMountRequested.addListener(
callback: function,
)
Raised when showing a dialog for mounting a new file system is requested. If the extension/app is a file handler, then this event shouldn't be handled. Instead app.runtime.onLaunched should be handled in order to mount new file systems when a file is opened. For multiple mounts, the file_system_provider.multiple_mounts manifest option must be set to true.
The callback parameter looks like:
(successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onMoveEntryRequested.addListener(
callback: function,
)
Raised when moving an entry (recursively if a directory) is requested. If an error occurs, then errorCallback must be called.
The callback parameter looks like:
(options: MoveEntryRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onOpenFileRequested.addListener(
callback: function,
)
Raised when opening a file at filePath is requested. If the file does not exist, then the operation must fail. Maximum number of files opened at once can be specified with MountOptions.
The callback parameter looks like:
(options: OpenFileRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
(metadata?: EntryMetadata) => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onReadDirectoryRequested.addListener(
callback: function,
)
Raised when contents of a directory at directoryPath are requested. The results must be returned in chunks by calling the successCallback several times. In case of an error, errorCallback must be called.
The callback parameter looks like:
(options: ReadDirectoryRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
(entries: EntryMetadata[], hasMore: boolean) => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onReadFileRequested.addListener(
callback: function,
)
Raised when reading contents of a file opened previously with openRequestId is requested. The results must be returned in chunks by calling successCallback several times. In case of an error, errorCallback must be called.
The callback parameter looks like:
(options: ReadFileRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
(data: ArrayBuffer, hasMore: boolean) => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onRemoveWatcherRequested.addListener(
callback: function,
)
Raised when the watcher should be removed. If an error occurs, then errorCallback must be called.
The callback parameter looks like:
(options: RemoveWatcherRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onTruncateRequested.addListener(
callback: function,
)
Raised when truncating a file to a desired length is requested. If an error occurs, then errorCallback must be called.
The callback parameter looks like:
(options: TruncateRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onUnmountRequested.addListener(
callback: function,
)
Raised when unmounting for the file system with the fileSystemId identifier is requested. In the response, the unmount API method must be called together with successCallback. If unmounting is not possible (eg. due to a pending operation), then errorCallback must be called.
The callback parameter looks like:
(options: UnmountRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
chrome.fileSystemProvider.onWriteFileRequested.addListener(
callback: function,
)
Raised when writing contents to a file opened previously with openRequestId is requested.
The callback parameter looks like:
(options: WriteFileRequestedOptions, successCallback: function, errorCallback: function) => void
The successCallback parameter looks like:
() => void
The errorCallback parameter looks like:
(error: ProviderError) => void
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Last updated 2025-08-11 UTC.
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