“2S4S” (2nd-hand items 4 Sale)

An app platform to buy and sell second hand goods

Design brief

Design a purchasing experience on a mobile e-commerce platform selling secondhand goods?

For anyone looking to sell secondhand goods, allowing potential buyers to negotiate the price is a great way to help close the sales. Buyers can save a few bucks and sellers get to offload their stuff. Secondhand marketplace also has its own unique characteristics and behaviours.

How would you design the purchasing flow starting from the price negotiation through to the checkout?

Problem/pain points

Most of the second hand classifieds are just a filter or another category on those platforms.

Classified website or apps are tailored to cater to a wide category of buy & sell items usually that are brand new or with retail prices. These are often focused on real estate, home rent, or car sale (bigger item categories).

Users sort to creating FB Groups to sell their pre-loved items in their respective areas or regions. The problem is these group pages aren’t really created efficiently to this kind of marketplace. Posts are often pushed down the timeline and there are no efficient filter method.

In these DIY groups, it is often that transactions are with meetups or the buyer mostly shouldering the pickup if these are larger items (i.e. furniture, kitchen appliance). That’s one of the main reason buyers ask for more discount just to cover that expense.

Security for purchases and essentially just how to pay for services or products online are one of the worries and problem of users—not only in this industry but in almost all online businesses. This is one more problem for the user-lack of trust. And this is one more of the reasons why they prefer meeting up and paying upfront with the seller.


There has been a number of studies online discussing on the different motivations of consumers nowadays that turn into buying second hand items.

“Consumers turn to second-hand consumption because they cannot afford new goods and have been excluded from traditional retail channels as ‘excluded consumers’”.

It might be that sellers just want to offload some stuff but a lot of sellers make a decent amount of money selling used/pre-loved items. Its evident on the popularity of platforms such as ebay for example, that have “sustainable” consumers.

  1. https://www.marketingweek.com
  2. https://www.verbraucherforschung.nrw/
  3. http://umu.diva-portal.org/
research notes

Research notes/writeups

Design Process


For this exercise, I skipped the persona development and instead I will “scratch my own itch” and look into myself as as example on how would I want this kind of platform to use. I myself purchases every now and then second hand items as well as sell them. I once sold all my plants when I moved out our apartment. I tried both posting on the social media groups and classified websites. It was very tedious and one should repost your listing if you want your post come up in the top results.

Competitor research

A competitive research/analysis is one way to ideate about products/services in the marketplace. Doing this highlights each strengths and weaknesses of their service/product. This will give us insights in making more informed decisions about your product strategy. I searched through local/regional classifieds as well as through social media channels (Facebook groups) to see the pros and cons of these.


Looking back at the given brief, one solution of making it highly user friendly and engaging is to have a more trendy user interface for the app. Place the main features of having a message function, a straightforward way to list items for sale, introduce an in-app service that picks up and delivers the bought/sold items to make the buyer/seller hassle free, and of course, have a secure/easy method of paying on items.

Ratings on the users is another way to promote “trustworthyness” as well as having verified users to begin using the app as one requirement to prevent scammers. Having this first in place will have a thriving community of users that are real people.

wireframe sketch notes

Wireframe sketches for app user journey.


Did some hand drawn wire frame sketches and rendered to digital layouts using Sketch App for the app screens.

Based on user research from exsting reports and to my own persona, I defined the relevant parts of the journey from having a verified login to begin with. Referred to other classified websites and apps to create the category hierarchy for the app. I omitted the automobiles/cars in this app since they are high value items and wanted to focus on smaller priced items (highest maybe furniture or home appliance items in this case though).

UI trend research/moodboard

Created a quick moodboard to experiment the website’s brand style as well as plan visual hierarchy of a project. I tried experimenting on bold and sharp colors for font and background for its minimal look and feel.

wireframe sketch notes

Moodboard trend research. I’m a fan of Duolingo ;)

Prototyping/Usalibilty testing

I opted to create hight fidelity screens for better user usability testing. Colour affects user behaviour, as well as creating animations that makes the eye follow certain actions. Created a simple prototype of the steps from logging in, choosing an item, buying, and posting to sell.


Created the High fidelity mockup screens in Invision.

Invision app prototype link:

Mobile app

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