natalya-api
You may want to use Paddle (which takes a bigger chunk of your profits) for that or some other marketplace: in that way Paddle is selling to end customers, taking a cut and then paying you in a business to business transaction.
You are also responsible for other types of taxes (assuming you are working via a limited liability corporation): sales taxes / VAT, corporate taxes, personal taxes, capital gain tax.
Some countries allow you to do some trading without setting up a company but as your earnings go up it will become either not very efficient from a tax perspective or not allowed by the law.
From my experience:
You need to pay VAT in European countries no matter where you're selling from (I use vatlayer.com for getting all the different VAT rates). You generally don't need to pay taxes in other countries until you reach a threshold of earnings / number of sales.
Quaderno.io is another service which track all these different factors for you.
Sales tax / VAT is displayed and charged to customers and you need to pay it to the relevant authorities every quarter.
Then you can pay yourself a salary (which is a cost) from the money you received in the company, based on your country's personal income rates. On what's left, on your company's profit you need to pay corporate tax rate, based on your country's corporate tax rates. On the remaining profits in the company you can generally chose to pay yourself dividends (on which you pay other taxes, based on your country's tax rates on dividends). If you sell your company, you'll have to pay capital tax gain taxes on the profit you made with the company (the delta between the company's capital and how much you sold it for).
TL;DR: you probably need an accountant.
I started with a couple of common ideas that we always had to implement for a lot of clients and I built a couple of simple Django-based services on Digital Ocean, in the free time I had from taking care of my newborn.
Therefore right now I'm running:
- https://getgeoapi.com: a GeoLocation API with additional data
- https://currency.getgeoapi.com: a Currency Conversion API
I'm terrible at marketing, so what I did was to leverage existing marketplaces. Slowly, over months, I started to build a reputation and build a userbase.
Profits range between 1000$-1800$ and I'm planning to expand to other marketplaces (I have a lot of customer who are on Shopify, even if I don't offer a Shopify app) and build other APIs. Hopefully I'll have more time once my sons go to nursery / school.
I use Stripe for direct sales on the website and RapidAPI (ex Mashape) as a marketplace.
I can't say RapidAPI is been smooth sailing: their payment processing is riddled with fees (thanks PayPal) and there are frequent outages and issues with their proxy. Still, I think using a marketplace can be a decent approach for developers who don't want to spend their days on reddit or finding their clients.