Liner has a simple purpose: it allows users to highlight text as they read. Want to highlight or annotate interesting sections of a research article? Give Liner a try. The Google Chrome extension and iOS application automatically syncs across multiple devices, allowing users to select a specific text or piece of information in an article or PDF. In addition, Liner also works with screenshots. This feature may appeal to anyone wanting to highlight a specific piece of text on a website during a presentation or as part of a social media post.