Hi guys, I have a small problem.

What does the store widget connect to? Stripe or paypal?

I would start by understanding how the users are using your product, mainly how frequent and why. Then, think about how much time you have to dedicate of your day, week or month to that one user. I mean, what does it take for you to have a product being used by 600 people?

Just get some data and conclusions and attack on a business model, whether a subscription based product, or a 'pay once' product.

It's hard, but you will never know how users could react if you don't even try. What's the worst thing that could happen? You need money, so it means you just cannot keep working on this for free. If you shut it down right now, you would make yourself a favor. Then, start charging for it however you think it's best.

If none of your users pay for the product, you will have to shut it down anyway. If only 10% of your users start paying for your product, you will have a starting point that will allow you to make new decisions.

Go for it!

Your revenue model should come from "Powered by". A huge marketing opportunity. "Powered by" is a known marketing opportunity to create backlinks. Contact me and I can help you earn money from this. gator8899 @ yahoo .com -- Thinking more, I can pay you for this service .... https://www.indiehackers.com/forum/powered-by-a-marketing-channel-nobody-talks-about-60ff198713

I think this is very cool. Reminds me of IFTTT and Airtable :)

Thinking out loud: What's the most popular widget? (why do people sign up?) If you can figure that out, perhaps it'd help you narrow your focus to serve those people and what they want to do better. For example, is it the instagram sync? Perhaps you can monetise by an advanced tool for instagram marketing?

Here's what I'd do:

1. Reach out to a few dozen of the users using the upload widget (you said this was your most popular product)
2. Make a simple landing page for the upload widget and replace your current page with that (keep the old page around, but link to it from your new front page)
3. Set a limit of uploads per month for the free version that's somewhere around the max uploads your most active users use every month (so if 10% of your users use 100 uploads per month, set the limit at ~100 uploads per month)
4. Email all the users who are close to the upload limit and ask them to upgrade. If they push back and don't want to pay, offer to extend their "free trial" for another year in exchange for feedback. Get feedback about why they don't want to pay, what they're using it for, what they WOULD pay for, and if they need any additional features
5. Use this feedback to turn your most popular product (the uploading) into a REAL product whose users you KNOW and UNDERSTAND and who you can market to, since now you understand their needs
6. Profit!!

On a related note, I ran across this article earlier today. I think you might find it interesting: https://chagency.co.uk/blog/increasing-user-retention/how-to-convert-a-free-user-to-a-premium-user/

EDIT: Btw, your website looks awesome and if I'd heard about it before, I'd be likely to recommend it to friends. I think your marketing copy could use some work and it'd be nice if there was some guarantee that you'd be around in a few years (especially if people are going to build you into their core business), but I honestly think you're totally onto something BIG. It's like a simplified version of Zapier that, if marketed correctly, could help thousands of small businesses create simple web apps!