Opera Dragonfly documentation

Storage Inspector

The Storage Inspector in Opera Dragonfly is accessible from the Storage panel in the application toolbar. The Storage Inspector displays all the data that is stored by the site or application on the client side – this includes cookies, HTML5 localStorage and sessionStorage, and Widget Preferences (for applications based on W3C Widgets, such as Opera Widgets and Opera Extensions).


A cookie consists of name-value pairs and associated metadata. An HTTP server can use the Set-Cookie header to pass the pairs to the browser in the HTTP header response. When the user agent makes subsequent requests to the server, the user agent uses the metadata and other information to determine whether to return the name/value pairs in the Cookie header.

The cookies panel lists all cookies set by the site being debugged: they are arranged in a table, sorted by domain and grouped by the host and path. Each row includes a column for each cookie attribute: name, value, expiry date etc.

Storage tab, showing a list of all cookies set by the current site

Types of cookies

There are various kinds of cookies. Opera Dragonfly provides a means to view and modify cookies as follows.

Session cookie

A session cookie, once set by the server, will be deleted at the end of the session (when the browser is closed or the session times out after a period of inactivity). These cookies are labelled with session in the Expires column.

Persistent cookie

A persistent cookie is not destroyed when the session ends. It lasts for the time period listed in the Expires column. The Expires column uses a human-friendly representation of the expiry date. Hovering over the expiry date will show the complete expiry date and time in a tooltip.

Secure cookie

Session and persistent cookies can also be secure. A secure cookie is encrypted when sent to the browser using the HTTPS protocol. It is not transmitted when using HTTP. Secure cookies are labelled with a tick icon in the Secure column.

HTTPOnly cookie

Session and persistent cookies can also be HTTPOnly. A HTTPOnly cookie can not be accessed by client-side scripting, which is designed to help against cross-site scripting attacks. HTTPOnly cookies are labelled with a tick icon in the HTTPOnly column.

Sorting and grouping cookies

Clicking on the headings of each column will sort the table in ascending/descending order by the column in question.

Selecting cookies

Clicking on a cookie's row will select it. It is possible to select multiple cookies by holding down the Ctrl / key while clicking on them.

The cookie context menu

Right-clicking a cookie brings up the context menu. From here, cookies can be added, edited, deleted and updated. Additionally, you can quickly choose to delete all cookies from the same domain.

Adding a cookie

A cookie can be added by selecting Add cookie from the context menu or by clicking on the Add cookie button. When the cookies are grouped, each domain has a Add cookie button, which pre-fills the domain field to that domain. When ungrouped, the button can be found at the bottom of the table, and the domain is pre-filled to the same domain as the previous cookie. The domain can be set to any valid domain, but it will not be shown if it doesn't match one of the listed domains. The cookie will be shown when inspecting the domain on which it was set.

Adding a new cookie

The expiry date can be selected using the provided calendar widget. Opera Dragonfly will automatically translate the date and time into a easily human-readable date. To set a session cookie leave the expires field blank.

Editing cookies

Cookies can be edited by double-clicking on the cookie row, or by selecting Edit cookie from the context menu, to bring up editable fields and then altering the text in each field. As with adding a cookie, editing a cookie to apply to a different domain will keep the cookie, but it will not show in the list as it will no longer apply to the current debugging context.

Deleting cookies

There are two options for deleting cookies. An individual cookie can be removed by selecting Remove cookie from the cookie row’s context menu. All cookies for a specific domain can be removed by selecting Remove cookies of domain name from the context menu of any cookie that is set on that domain.

Web Storage

The Web Storage API defines persistent storage of data using key-value pairs in web clients. Web Storage can fulfill the same use cases as cookies, without many of the drawbacks such as increased storage space or the ability to access stored data for the same website across two different windows.

The Storage Inspector separates the two types of Web Storage into their own sub panels. Each entry is displayed in a key-value list.

local storage

Session Storage

Session Storage is somewhat similar to a session cookie in that it lasts for the lifetime of the session and is then destroyed. Data stored with Session Storage can be found in the Session Storage panel.

Local Storage

Local Storage is more like persistent cookies. The data stored with Local Storage is not destroyed unless the user deletes it through the browser UI, or for security reasons. Data stored with Local Storage can be found in the Local Storage panel.

Manipulating Web Storage

Session and Local Storage can be added, edited, and deleted in the same way as Cookies. The only difference is that the interface is simpler due to Web Storage only having a key and value for each entry.

Widget Preferences

Widget Preferences use the same Storage interface as Web Storage, but they are specific to applications implementing the Widgets API – Opera Widgets (which are now deprecated) and Opera Extensions.

Each widget or extension has its own storage area to store its preference data. The data in this storage area can be found via the Widget Preferences panel, which remains blank for websites and applications that do not implement the Widgets API.

Data in the Widget Preferences panel can be manipulated in exactly the same way as Web Storage entries.