Web Intents: A fresh look

Paul Kinlan

We have a huge problem on the web today. If I built an image gallery application and I wanted to let users edit an image so that they can remove red-eye from a photo I either have to build an application that edits the images, or integrate with a 3rd party solution. Doing this is hard and stops you from building an awesome image gallery; and what happens if the user has a favorite service that they already use to remove red-eye? Simple, you have a frustrated user.

We have a solution!

In December 2010 I announced a project called Web Intents whose goal was to allow developers to build applications and services that could work with each other, but not need to explicitly know about each other – the concept has heavily inspired by the Intent system in Android, although the API bore no resemblance. It would allow you to build applications using just the functionality your cared about, and then delegate the other functionality to the users preferred choice of service.

After some conversations, I moved to try and support Web Introducer as a specification over Web Intents. For one reason or another this didn’t quite work out so I decided to plug away at revising the WebIntents work that I started back in November.

It turns out there is a lot of interest internally with the idea of Web Intents and how it can work in modern browsers. We set up a small crack team and after a flurry of work, speccing and prototyping how we think it might look we have put a prototype API on to Github. Have a play, it is really easy to get started.

So what changed?

A lot as it happens. It is not the same as the initial project that I experimented with, although the goals are the same. We have an objective to make the developer experience of the API so painless that most developers can start integrating with applications in 5 minute of reading the spec – in fact we want it so that most developers can just copy and past examples and it will work with their service. We have tried to drastically reduce the API surface and make it so there is literally only one or two lines of code you need to start an activity.

Service registration has been made even easier that my initial project through the use of a new tag, for example:


This small tag, that is included in the head of your application will signal to the browser the intention to handle a “share” action for a selection of URI’s (think “share this page”), and will register it in the system so that the user can choose it when a client application wants to provide “share” functionality in their app.

When the service is chosen by the user, and the service is loaded the intent data is passed to the open application and is available on the window.intent object.

For clients to initiate an Activity it is easy too. Simply declare an intent and start the Activity as follows:

var intent = new Intent();
intent.action = "http://webintents.org/share";
intent.type = "text/uri-list";
intent.data = "http://paul.kinlan.me";


The system will take care of the service resolution for the action and compatible data formats and give the user the choice of using their favorite application to handle the “share” intent.

I have only just touched the surface of what you can do with the API. There are a lot of things that you can do with the API over and above what I have described in this 5 minute overview. A selection of examples can be found at http://examples.webintents.org/ where we show you how to build applications that solve some common use-cases. I particularly like the cloud kitten service provided by the “pick” example.

We are working with Mozilla to define a common approach to solving the challenges that web integrators face today. We are interested in hearing your thoughts and we are still thrashing out the API so bits of it might change but the intent is still the same.

My closing thoughts are: “This project will fundamentally change and improve the way we build applications on the web today for our users.”