Here is my product: https://matchkraft.com/. It is a marketing toolkit. I think you need to ask for feedback, asking why users don't want to pay for a premium subscription. So far, you are getting new users that is a good sign you are going to the right direction. Maybe, who is your ideal customer or maybe your product is ok but need more visibility (maybe paying ads). Try to get active users. I really want to... Source: 12 months ago

Calling a 3rd party API: There is a complete ecosystem providing "google-sheets-as-DB". I personally tested and recommend https://sheetson.com/ but there are a lot more with free tiers https://sheetsu.com/ https://sheety.co/. Source: about 2 years ago

Yes I also made wip.co startup.jobs highscore.money expensive.chat buildinpublic.com pr.co caption.cat getfaces.com requestforstartup.co openmargin.com eatmore.io pushmore.io [😁.to](https://😁.to) linkhyper.com tweet.photo sp-forums.com tunnelvision.xyz hundredunderhundred.com. Source: over 2 years ago

Marc Köhlbrugge is the founder of a seemingly never ending list of products. Examples include BetaList (startup discovery platform), Startup Jobs (job board) and WIP (community of makers). More recently he launched BuildInPublic.com (Twitter community). He has also made more experimental products like Highscore Money (pay your way into a leaderboard) and Expensive Chat (chatroom where you pay 1 cent per letter). Source: over 2 years ago