How will you market a productivity tool for freelancers?

Hello everyone, we are just about to launch https://www.simpletasking.com , a multi-project management platform. We believe it is extremely helpful for freelancers as it lets the user keep up and quickly switch between multiple projects. So need to set up Slack and Trello for each client, Simpletasking does this and also adds a multi-level thread and videoconferencing! (Users are still able to decide what features to enable on per project bases, ex, you may have a project with just chat enable).

Marketing is a challenge to us, so we are looking for ideas on how to grow our product.

Thank you!