This is an experimental feature
Because this feature is still in development in some browsers, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental feature is subject to change in future version of browsers as the spec changes.

Asynchronous API

The asynchronous API methods return without blocking the calling thread. To get asynchronous access to a database, call open() on the indexedDB attribute of a window object. This method returns an IDBRequest object; asynchronous operations communicate to the calling application by firing events on IDBRequest objects.

• IDBCursor iterates over object stores and indexes.         
• IDBDatabase represents a connection to a database. It's the only way to get a transaction on the database.
• IDBFactory provides access to a database.
• IDBEnvironment provides access to a client-side database. It is implemented by window objects.
• IDBIndex provides access to the metadata of an index.
• IDBObjectStore represents an object store.
• IDBOpenDBRequest represents a request to open a database.
• IDBRequest provides access to results of asynchronous requests to databases and database objects. It is what you get when you call an asynchronous method.
• IDBTransaction represents a transaction. You create a transaction on a database, specify the scope (such as which object stores you want to access), and determine the kind of access (read only or write) you want.  
• IDBVersionChangeEvent indicates that the version of the database has changed.

Early version of the specification also defined the now removed interface. They are still documented in case you need to update previously writtent code:

• IDBVersionChangeRequest represents a request to change the version of a database. The way to change the version of the database has since changed (by calling IDBFactory.open() rather than IDBDatabase.setVersion()) and the interface IDBOpenDBRequest now have the functionality of the removed IDBVersionChangeRequest.

Synchronous API

To get synchronous access to a database, call open() on the Unimplemented indexedDBSync attribute of a worker object. This returns an IDBDatabaseSync object, which enables you to create, open, and remove object stores and indexes, set the version of the database, and create transactions.

• IDBCursorSync iterates over object stores and indexes.
• IDBDatabaseSync represents a connection to a database. It's the only way to get a transaction on the database.
• IDBEnvironmentSync provides access to a client-side database. It is implemented by worker objects.
• IDBFactorySync provides access to a database.
• IDBIndexSync provides access to the metadata of an index.
• IDBObjectStoreSync represents an object store.
• IDBTransactionSync creates a transaction in the database.

Shared interfaces

The following interfaces are used by both the synchronous and the asynchronous APIs.

• IDBDatabaseException represents exception conditions that can be encountered while performing database operations.
• IDBKeyRange defines a range of keys.

Example

A powerful example of what IndexedDB can be utilized for on the web is the example by Marco Castelluccio, winner of the IndexedDB Mozilla DevDerby. The winning demo was eLibri, a library and eBook reader application.

Browser compatibility

Storage limits

For Google Chrome, you can have up to 5 MB of storage, by default. Installed apps can have unlimited storage if you set your manifest file to have unlimited storage and your user grants that permission to your app. 

See also

• Basic Concepts About IndexedDB
• Using IndexedDB
• Storing images and files in IndexedDB
• A simple TODO list using HTML5 IndexedDB.
  Note: This tutorial is based on an old version of the specification and does not work on up-to-date browsers: for example, it still uses the removed setVersion() method.
• Indexed Database API specification
• IndexedDB — The Store in Your Browser
• IndexedDB Support in browsers
• IndexedDB Examples