Fintechs are new-age banks that provide more ease to the users. They are more secure and prevent fraud compared to the traditional baking system. However, you must conduct due diligence before investing or depositing money in any fintech company.
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If you mean safe in as a stock option, then you have to differentiate. Long-term it's definitely a good investment and generally safe, if you do your due diligence and don't bet on a failing horse of course.