Helloslide is a smart service that transforms PDF slides into a rich audiovisual format by letting you add audio to presentations in PDF format. This web application works by adding speech to each slide and then automatically generates the audio. Simply upload a presentation, type the text you want to hear for each side and the audio will instantly be generated for the particular text. With HelloSlide, your slideshow is just like a live lecture. The service allows you to customize slides and add audio for them, which can be listened to instantly.