Mercari uses OpenAI to improve listings and help sellers
In plain words
Japanese marketplace Mercari uses GPT-4o mini to enhance product listings and give sellers better support.
What happened: Better listings and seller help across the whole marketplace.
Source: openai.com ↗
How to do it yourself
Our suggested steps. The company didn't publish theirs.
- 1
Take 3-5 clear photos of the item.
- 2
Upload them to ChatGPT with the prompt below.
- 3
Check the details it suggests (brand, size, condition) and correct.
- 4
Paste title, description and price into your listing.
- 5
Relist unsold items after 7 days with its suggested price drop.
The instructions to give the AI
Paste this into ChatGPT (the free plan is fine), swap the [brackets] for your details, and test it on a few real examples.
Agent instructions (prompt)
From these photos, write a marketplace listing for [platform]: title (max 60 chars with brand/model/size), condition, 5-line description, item specifics, and a suggested price range in [currency] based on typical resale values. Ask me to confirm anything you can't see.
[Highlighted] = replace with your own details before you run it.
What you should get back: "Sony WH-1000XM4, black, very good condition — 5-line description and specs, ready to post."
Written by Quickly and Good, inspired by this case.
More detail: tools, prices and what you'll need
The company used: OpenAI GPT-4o mini
You could use: ChatGPT (with image upload) for marketplace sellers on eBay, Mercari, Trade Me, Facebook
- ChatGPT
General AI assistant: writes, summarises and answers from files you give it.
Free plan; paid plans available · Official site ↗
Prices from each tool's own pricing page, checked Oct 2026.
What you'll need
- ☐A ChatGPT or Claude account
- ☐Your own documents, templates or examples
- ☐The agent instructions (prompt)
- ☐A habit of checking every output before you use it
Can I do this myself?
Yes. You can try this today with a chat assistant and your own files.
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