You'll need to include more than a basic level of development and calculation in your spreadsheet. There are lots of free spreadsheets on the web. Most of which are very simple and easy to build. People aren't going to buy a spreadsheet that they can get for free. Take yours to the next level by adding all the value you can imagine. Then research on how you can offer a little bit more on the development and functionality side.
Financial templates are highly complex and they deal with very large and advanced calculations. These spreadsheets are used in mortgage, loans, and property investments and so on.
Apart from these very popular categories, business owners can find various other types of spreadsheets solutions by collaborating with a prominent, reliable spreadsheet-solution-providing company and opt for the 'Personalized Spreadsheet'; solutions that are especially designed to meet your imposed criteria, created from scratch, tailor-made and adapted to your particular needs.
You'll need to find a way to make your spreadsheet accessible. You can build a website, which will require paying for a domain, hosting, site security, dealing with an internet transaction service, graphic design, content for the website, marketing your website, Search Engine Optimization, and all the other madness that comes with managing a site.
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