I'm building Trezow, a free-sharing marketplace, and almost every design decision came back to one question: how do two people who have never met feel safe enough to hand something over? This is how the flow ended up looking, and why.

1. Ask first, don't just take

On a classified site you can message a seller about anything. In a free marketplace, that opens the door to dozens of "is this available?" messages for one sofa, most of them never followed through.

So instead of an open message box, the receiver sends a request. It carries a few small choices (how they'd like to collect, a short note) rather than a blank text field. The giver sees a clear list of requests and decides. That one change turns noise into a decision.

2. The giver is always the one who accepts

Nothing moves forward until the giver accepts. Chat opens only after that. Two reasons:

• The giver controls who knows their pickup area.
• It removes the pressure to answer every message right away.

Declining is a normal, one-tap outcome, not an awkward conversation.

3. Show an area, never an address

Items show a pickup area, not a street address. The exact spot is shared in chat, after acceptance. It is a small thing, but it is the difference between "a stranger can find my home from a listing" and "I decide who gets that detail".

4. A handover code to close the loop

Free items have a quiet problem: nobody can tell whether a pickup actually happened. People forget to mark things as given, and others keep requesting an item that left days ago.

A short handover code solves that. When the receiver arrives, the code confirms the handover from both sides, and the item is marked as given. It is simple, it needs no payment infrastructure, and it gives both people a clear "done" moment.

5. Make "not now" cheap

A few rules keep the exchange healthy without heavy moderation:

• A limit on how many requests one person can send in a day, so the giver isn't flooded.
• A cool-off before asking for the same item again after a decline.
• Withdrawing a request is always possible, and visible to the giver.

None of these are clever. Together they make the default behaviour polite.

What I'd still like to improve

• Making the first-time experience clearer, so a new user understands the flow in seconds.
• Helping people who don't have an item to give yet, which is why I added a "make a wish" feature where you can ask your neighbours for something specific.

Try it, tell me what's missing

Trezow started in India and works anywhere, on the web at trezow.com and as an Android app.

If you've built a marketplace, or used one, I'd love to hear: what's the one moment where you decided to trust (or not trust) a stranger?