All your exchanges go through the built-in chat, reached from the Messages tab. That's where you talk to ask questions and arrange a sale.
To contact a seller:
- Open their listing, then tap Message ;
- Write your question (availability, condition, pick-up spot…) ;
- You can also share photos straight into the conversation.
Good news if the other person speaks another language: the chat offers automatic translation, with a button to switch between the translated text and the original.
If the seller made their number public, a green Call button appears on the listing so you can phone them directly. For your safety, keep your exchanges in the app at first and never share banking details by message.