Based on the facts as you have presented them:You are selling a product, as I see it, and not a service - although there's something of a gray area here, this is more like an intangible asset than it is providing a personal service for compensation. That product is being offered to US-based customers who are using it in the US - your focus is building up your market in the US, and you are doing that under the auspices of an LLC which is US-based. Looking at all of the facts and circumstances surrounding the conduct of your business, as you have presented them and as the IRS will look at them if asked, I conclude that you are conducting a business in the US and your income from US sources is effectively connected with the conduct of that business in the US, which means that you are subject to US taxes on that income.With that conclusion, Form W-8ECI is the proper form to prto your US sources if you wish to prevent withholding on the income from your business.I want to add one point, since this seems to be coming up frequently - while an LLC is a disregarded entity for tax purposes, it is still a legal entity in the US - and the fact that you, as a nonresident alien, choose to operate a business under the auspices of a US-based LLC is a piece of evidence that can, under the appropriate set of facts and circumstances, be used by the IRS to support an argument that you are conducting business in the US and that your income from that business that comes from US sources should be taxable in the U.S. You should not assume that as a nonresident alien you have carte blanche to create a US LLC, operate a business under its auspices, and then at tax time argue that the income should not be taxable in the US because the LLC is a disregarded entity. The IRS will look at all of the facts and circumstances surrounding your business, including your choice of a US-based entity as the face of your business, and while that decision alone won't be dispositive, it will certainly be considered.