Add that to the title!

The service looks really great, it solves a problem, it looks ready to be used in production, market that. "docamatic makes document creation easy using HTML template and an API" or such.

HN is fairly technical audience but the tools you used are secondary.

My feedback: Terms-of-service say it's based in the UK, privacy policy talks about safeguards when data travels from Europe to outside Europe. I think that might need to be updated to the GDPR regulation that came into effect last year.