This is a very well done site but perhaps a bit too much of a demand test to be on HN which is extremely tech heavy (the typical reader is likely to wonder "I can already ask an LLM to do this. Why would I pay this company to do this for me?"). This would do very well on other, less tech heavy sites. I would also suggest some changes.
Above the fold, there's a lot of pitch how Draw.io requires "No credit card, no trial periods, no BS." and "It's genuinely free - has been for years, always will be. That's why millions use it, and why converting your images to Draw.io format makes so much sense. Your converted files will always be editable, no subscription required"
Below the fold and at the very bottom, this service itself starts off at $5/mo on sale right now.
I would imagine this would confuse people. They might interpret that this service is free too, then be suprised at the "no free tier" and some are going to be outright angry and very vocal about it.
So I would change the messaging along the lines of "We help you convert images into Draw.io so you pay us just once for the diagram you want converted"
To enhance the message, I would further say "This is how much we sponsor Draw.io for enabling our own business" and write blog posts about the struggles to build the service or even open source the methods to fine-tune a model to do the conversion.
Good luck, this is valuable!