There are many online courses available for digital marketing. Some popular options include:

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

2. Udemy: Has a wide range of digital marketing courses, including paid and free options.

3. Coursera: Offers digital marketing courses from universities and industry experts.

4. HubSpot Academy: Offers free digital marketing, sales, and service courses, as well as certifications.

5. Hootsuite Academy: Offers social media marketing courses and certifications.

6. Digital Marketing Institute: Offers a range of digital marketing certifications and courses, including a Professional Diploma in Digital Marketing.

It's always wise to go through the reviews and ratings of the course before enrolling and choose the one that fits your needs and preferences best.