- Cold emailing. Find people in your niche and personally contact them, find people who are likely to need an app and make a personalized offer.<p>- Content Marketing + Social Media. Write a blog or make a youtube channel, share free value, submit links to HN/Subreddits, use it to advertise your service's landing page. This can be combined with smart PR/Influencer marketing(guest blog for people, get people to share your content), and SEO(think about long-tail very niche keywords that you can rank for).<p>- "Engineering as marketing" - create open source or free software that your potential clients will want to use, use it to drive traffic to your page. Look at draw.io or chapp.is for example.<p>- Facebook ads. Target audience in your niche, make an appealing ad that offers free consultation. If you think you can afford $1-2 per lead, that could be the best way to quickly test how well your offer will convert.<p>- Collaborate with people who already have clients(for example contact app designers, offer them development services).<p>- Referrals and word of mouth. This is kind of a chicken and the egg problem at the beginning, but after you have first clients, they might bring more business or recommend more clients. Consider giving people heavy discounts at the beginning, if you think they will bring you more business in the future.