There are a variety of free digital marketing courses available online, depending on your interests and goals. Some popular options include:

1. Google Digital Garage: Offers a range of free courses on digital marketing topics, including search engine optimization (SEO), social media marketing, and digital advertising.

2. HubSpot Academy: Offers a range of free marketing, sales, and service courses, including inbound marketing, email marketing, and content marketing.

3. Digital Marketing Institute: Offers free online courses, webinars, and tutorials on a variety of digital marketing topics.

4. Facebook Blueprint: Offers free online courses, webinars, and certifications on Facebook and Instagram marketing.

5. Coursera: Offers free online courses on digital marketing and related topics from leading universities and organizations, such as the University of Illinois at Urbana-Champaign, and Google.

6. edX: Free online course, they have a lot variety of digital marketing, from SEO, Social media, E-commerce and many more, from well-known institution such as Harvard, MIT and etc

It's worth noting that some of these courses may require you to create an account, and many offer paid certifications for a fee.