Marker.io is a visual feedback and bug reporting tool primarily used by web development and design teams. It allows users to capture screenshots, annotate them with comments and drawings, and then send them directly to project management or issue tracking tools like Jira, Trello, GitHub, or Asana.

The tool simplifies the process of reporting bugs or providing feedback on websites or web applications by streamlining communication between developers, designers, and stakeholders. Instead of relying on written descriptions of issues, users can visually pinpoint problems or suggest changes, making it easier for teams to understand and address them efficiently.