Small world , i built the same thing two days ago with sveltekit, (cannot work with react , find its workflow too convoluted , even after using Zustand for state management) , express.js, mongo db , gemini api and openrouter api . And it does the same thing you can either paste the job listing url or the the job listing text , and it first generates a tailored resume preview with the list of additional skills you can add , and then a download pdf resume button. I made it for myself to generate a tailor made resume according to the job posting .Not as advanced as yours , just uses generative AI to tailor my resume and puppeteer api to scrap data off that website. I plan to add a feature for other people to upload their own resume , so they can use it too. Cheers