## What Does It Do?

**WebJack is a wired, bidirectional data link between the Arduino Uno and your phone, established via headphone jack.** It uses two distinct frequencies for a modem-like serial transmission of data. WebJacks runs in the browser and its goal is to provide a way to read sensors without the burden to install native applications. Look for recent updates on Public Lab [here](http://publiclab.org/tag/webjack).

## Activities

This is a list of community-generated guides for specific applications and the development of WebJack. These [activities can be categorized](https://publiclab.org/wiki/activity-categories), and some may be more reproduced -- or reproducible -- than others. Try them out to build your skills, and help improve them by leaving comments. Together, we can repeat and refine the activities into experiments.

### Activity grid

[activities:webjack]

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## Frequently Asked Questions

<a class="btn btn-primary" href="/post?tags=question:webjack&template=question">Ask a question about WebJack</a>

[notes:question:webjack]

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[![IMG_0138_web.JPG](//i.publiclab.org/system/images/photos/000/017/089/large/IMG_0138_web.JPG)](//i.publiclab.org/system/images/photos/000/017/089/original/IMG_0138_web.JPG)

WebJack is an open source client-side JavaScript library that acts as audio modem. It is built for use with [SoftModem](https://github.com/arms22/SoftModem), the Arduino-side code. For example, with WebJack you can transmit:

* data as text
* binary data
* Firmata RPC messages

##Build a data link with WebJack

Instructions on the circuit and software needed for WebJack can be found here:

https://publiclab.org/notes/rmeister/07-18-2016/webjack-testers-needed

### Demo WebJack applications

- [Using Firmata with WebJack as transport](https://publiclab.github.io/webjack-firmata/example):

<iframe width="560" height="315" src="https://www.youtube.com/embed/eWr3kahwo78" frameborder="0" allowfullscreen></iframe>

- [WebJack demo website](https://publiclab.github.io/webjack/examples)


###Notes:

- For more information about WebJack, post a question to the "dev" mailing list [here](https://groups.google.com/group/plots-dev)) (also listed in the left sidebar)
- The github repo of WebJack is [here](https://github.com/publiclab/webjack)