I built a local-first image checker for marketplace sellers

Marketplace sellers often discover image problems too late.

A product photo may look fine in an editor, but after uploading it to a marketplace it can become:

• cropped in search thumbnails
• too small for zoom previews
• the wrong aspect ratio for a sales channel
• risky for Amazon-style main image requirements
• awkward when reused across Etsy, Amazon, TikTok Shop, Shopify, eBay, or Walmart

I wanted a simple preflight step before publishing product images, so I built ListingPic:

👉 https://listingpic.com/

What it does

ListingPic is a browser-based marketplace image checker and resizer.

You upload a product photo, choose the marketplaces you care about, and get a readiness report covering things like:

• image dimensions
• aspect ratio
• file type
• file size
• thumbnail crop risk
• safe-area positioning
• marketplace-specific warnings

The goal is not to replace manual review. It is to catch obvious image risks before sellers waste time uploading, previewing, deleting, resizing, and re-uploading.

Why local-first?

A lot of product photos are sensitive:

• unreleased SKUs
• private product photography
• branded assets
• client images
• images sellers do not want copied or stored elsewhere

So ListingPic processes images locally in the browser.

Your images are not uploaded to our server for analysis.

That also makes the tool fast for quick checks: drop in an image, review the warnings, adjust before publishing.

Current checkers

The MVP includes marketplace-focused checks for:

• general marketplace readiness
• Etsy image checks
• Amazon product image checks
• TikTok Shop image checks

There are also entry points for Shopify, eBay, and Walmart workflows.

Example use case

Imagine you have one product photo and want to reuse it across multiple channels.

ListingPic can help answer:

• Is the image large enough?
• Will the product be cut off in thumbnails?
• Is the image close enough to square for a channel that prefers square previews?
• Is the product too close to the edge?
• Do I need a separate crop for Etsy or TikTok Shop?
• Do I need to manually review Amazon main image requirements?

What I learned while building it

A few product lessons stood out:

1. Sellers do not think in pixels first.
   
   They think in terms like “will this upload?”, “will the product be cut?”, and “will this hurt my listing?”

2. Different marketplaces create hidden image work.
   
   A single photo may need different crops or checks depending on where it is published.

3. Privacy matters even for small tools.
   
   Local browser processing is a strong default for tools that touch product photos.

4. The hardest part is not just resizing.
   
   It is explaining image risks in a way that non-technical sellers can act on quickly.

What I am improving next

I am still iterating on the tool and would love feedback from developers, indie makers, and marketplace sellers.

Possible next improvements:

• clearer platform-specific recommendations
• better examples of risky vs safe crops
• batch checking multiple images
• downloadable marketplace-ready variants
• more detailed guides for Etsy, Amazon, TikTok Shop, Shopify, eBay, and Walmart

If you sell on marketplaces or build tools for ecommerce sellers, I would love to know:

• What image checks are missing?
• Would batch processing be more useful than a single-image checker?
• Which marketplace image rules are the most painful in practice?

You can try it here:

👉 https://listingpic.com/

Thanks for reading — feedback is very welcome.