CoverageImpact is a standalone tool made by the team here at CoverageBook. Its free to use!
You can import spreadsheets from your favourite PR tools to create a coverage timeline graph, with the option of plotting other data on top (sales, sign ups, traffic/visits data) to visualise the impact of your PR activity.
Visit https://coverageimpact.com/ to get started!
If you're a CoverageBook customer, you can also import any charts you make as Slides to your report. Click here for how to import slides.