How I Built a 273 Template AI Ad Generator as a Solo Dev

Two weeks ago I had an idea: what if you could drop any brand's URL and get professional ad creatives generated instantly? Today, Silo has 92 users, 273 ad templates, and people are actually using it to generate real ads for their brands. Here's how I built it. The Stack Nothing fancy: Next.js 14 (App Router) Prisma + SQLite on Fly.io (single machine, volume mounted) Gemini AI for both Brand DNA extraction and image generation Stripe for billing Google OAuth for sign in Total infrastructure cost: under $10/month. SQLite on a single Fly.io machine is honestly all you need until you hit thousands of users. How Brand DNA Works When a user drops a URL, here's what happens: We scrape the page using Cheerio (server side, no headless browser needed) Extract all visible text, meta tags, Open Graph data, and image URLs Send everything to Gemini with a detailed prompt asking it to analyze: brand colors, typography style, voice/tone, target audience, key messaging The AI returns structured JSON w