The Difference Engine has been developed to provide portable access solutions, particularly for small-scale companies which produce site-specific or experimental work, outdoor shows, work performed in promenade or in-the-round, or performances in unusual or non-traditional spaces.  It delivers captions to audience members’ own mobile devices via an App or browser. It is not reliant on a WiFi connection, and where needed it can be run off a battery pack if there is no available power supply. It is operated directly by the organisations or venues who hire it, making it an affordable solution, particularly for small scale companies.

The Difference Engine is currently available for captioning events – see below for information on how to hire the system. We are also developing audio description, multi-channel captioning (for – amongst other things, translation),  programme content and more.

Using/hiring the Difference Engine

If you are interested in hiring the Difference Engine to caption performances or events, please download and complete this booking request form and send it to along with any additional info about your plans (including tour details if you have them) and any questions you may have. We will contact you to confirm availability and to discuss hire rates: these are currently subsidised as we continue to develop and test the system, and all hirers are asked to support this ongoing development by actively targeting D/deaf and hard of hearing audiences, and seeking feedback from them. Please also see our FAQs page for further information.

How it works

The operating system is easy to use: the company producing the show edits their script into caption-sized chunks of text and adds in any other description of sound effects/music, then uploads this to the Difference Engine system in advance. We recommend that the editing is done by someone in the creative team – and you might want to work with a professional captioner on this if you are new to it. Then you need someone to operate it during the show: it’s not technical – you just need someone who knows the show and understands cues and pacing.  This video gives an idea of how the system works:

Audiences access the captions via an App or through a browser connection (you can direct them to the Audience page of this website for links to download the App, or to get browser instructions)


We provide full instructions on how to use the system (which can also be downloaded from our Resources page). Most people using the Difference Engine have run it just by using the written instructions, which takes you through the process step by step. You can also get in touch via email with any queries.