Building a free image toolkit zero-server architecture, ad-supported

I launched LeanImg (https://leanimg.com), a free browser-based image toolkit with 4 tools: compressor, resizer, cropper, and format converter.

The idea: Most online image tools upload your files to a server, process them, and send them back. But modern WebAssembly lets you run production-grade codecs (MozJPEG, OxiPNG, libwebp, libavif) directly in the browser. No server needed.

Why I built it: I'm a web developer and I constantly need to compress, resize, crop, and convert images for client projects. TinyPNG only compresses. Squoosh only handles one image. iLoveIMG uploads everything. I wanted all four tools in one place with no upload.

What's live:

• Compressor — JPEG, PNG, WebP, AVIF with smart presets

• Resizer — exact dimensions, percentages, social media presets

• Cropper — interactive visual crop with aspect ratio presets or freeform

• Converter — 50+ format pairs across 11 formats (JPG, PNG, WebP, AVIF, HEIC, GIF, SVG, TIFF, BMP, ICO, PDF)

Architecture:

• Next.js 16 static site deployed on Vercel

• WASM codecs via jSquash

• Zero backend — the entire app is client-side

• Cost to run: just the domain and hosting

Monetization: AdSense only. No premium tier, no API product. Revenue = traffic x RPM. Each tool page is both a keyword target and an ad surface — the multi-tool approach multiplies traffic and revenue.

Roadmap: More tools planned: watermark, background removal, rotate, etc. Each new tool adds pages and cross-links, compounding SEO and traffic.

Would love feedback from other solo builders. How do you approach monetization on free utility tools like that?