Entrepreneurship starts with creating a business plan. Part of that business plan is identifying your target market, your competition, and defining how you are unique. It's not so much that something has been done before but rather what sets you apart. If your concern is legal, then patents (google scholar) and trademarks are what you should be looking at. Copywrite is a bit more difficult but after performing your market research you should have an idea of what's out there. In other words, who is your target market and what are they using now that your startup is aiming to satisfy?
Unless you're copying someone else's code, text or graphics, you're not infringing their copyright. Copyright would be the "easy one" since it's near impossible to accidentally infringe, unlike trademarks or patents.
Entrepreneurship starts with creating a business plan. Part of that business plan is identifying your target market, your competition, and defining how you are unique. It's not so much that something has been done before but rather what sets you apart. If your concern is legal, then patents (google scholar) and trademarks are what you should be looking at. Copywrite is a bit more difficult but after performing your market research you should have an idea of what's out there. In other words, who is your target market and what are they using now that your startup is aiming to satisfy?