‘Crowdfunding’ may be generally used as an umbrella term for describing the use of small amounts of money, obtained from a large number of individuals or organizations to fund a project, a business, a personal loan or for other needs. This may happen through an online web-based platform.
Factors like the size of investment/ donation, purpose/ ROI, online presence, stage of funding and the like may help differentiate between different types of crowdfunding, like donation based, reward based, equity crowdfunding, P2P. The laws may apply accordingly.
Since you have referred to milaap and ketto, you may want to be doing donation based crowdfunding. In this regard, depending upon the kind of donation, eligibility of the donor and eligibility of the donee involved various laws may apply such as Foreign Contribution Regulation Act, 2010 (in case donation involves foreign funds), Income Tax Act (if the donor is seeking tax exemption) and CSR Rules (if the donor is giving the CSR funds) and the like. KYC process and requirements may also be determined on the basis of kind of crowdfunding you wish to facilitate online.
Broadly, one may register as an NGO only if the aim is to not generate profits out of the platform. However, in case one wants to make profit, the a private limited company may be suitable. This is one of the may criteria which you may want to assess before you choose the form of legal entity for your startup. This article may help regarding other criteria. https://economictimes.indiatimes.com/small-biz/legal/top-ten-things-to-consider-while-choosing-a-legal-entity-for-your-start-up-in-india/articleshow/47320669.cms