A question related to AppExchange, Is it mandatory to become a Salesforce ISV/OEM Partner to upload unmanaged package on AppExchange. I want to upload some apps(Those will be unmanaged packages) on AppExchange. Do I need to become Salesforce's partner? As a developer, Can I upload some app without being a Salesforce Partner? Is it possible ?
You can upload and distribute unmanaged (and even managed) packages, but you won't be able to list it "publicly." Users can still install it if they can get a link to it, for example, from your website. If you want to actually have it be searchable directly in the AppExchange, you need to get certified (i.e. pass security review), which requires being in an agreement as an ISV/OEM. Being certified makes your package "limitless", meaning the code, objects, fields, and so on don't count against the global org limits (e.g. number of objects, fields per object, number of code characters...). I have personally uploaded packages that were never certified and could be installed by any org, although not in a number of years. Some consulting companies will develop code in a managed/unmanaged package, and then provide links to their clients to install the package.
You can package and distribute unmanaged packages without being an ISV Partner, but you cannot list them publicly on the AppExchange. You would share the install link for the package to the end-consumer of it, but again, they would not be able to find/install from the AppExchange.
The process to become an ISV Partner is pretty time consuming. There are several business/technical questionnaires and discussions to go through, legal contracting to become a partner, and then the extensive Security Review process to get your application approved to be listed on the AppExchange. It is uncommon for an unmanaged package to be approved, but it can happen. Estimate a minimum of 6 months to go through the process to get it listed publicly.