Adding a deeply integrated online marketplace feature to WhatsApp for efficient buyer-seller communication.


UX Designer
(with mentor guidance)

2 weeks

Tools Used

The Challenge

  • It can be difficult to tell if a buyer/seller might be a scammer.

  • Users want to limit the amount of personal information they share with buyers/sellers.

  • Irrelevant listings sometimes show up in search results, making it difficult to find the right item.

  • There is currently no easy way to do in-app payments for online marketplaces.

Project Goals

  • Create an in-app local market allowing users to buy, sell, and browse goods within their area.

  • Utilize WhatsApp’s existing chat feature to simplify communication between buyers and sellers.

  • Establish Bazaar as a safe place to shop and protect user privacy.

  • Allow users selling multiple items per listing to easily reference specific products.

My Approach

  • Allow users to see if a buyer/seller is verified with positive reviews/ratings.

  • Separate Bazaar communication from general chats.

  • Include comprehensive filters for both regular search results and comparison tools to find similar listings.

  • Allow users to complete all transaction-related activity within their chat window (making an offer, setting up a meeting date/time/location, upselling multiple items, payment).

This is a fictional project to explore adding a feature to an existing app.

01 Research


Why an Online Marketplace?

WhatsApp has recently surpassed 2 billion users, and part of the reason is the company’s commitment to privacy with strong end-to-end encryption. The app is free to download and does not display any advertisements. But this also means it lacks a revenue stream. The company wants to begin turning in a profit in a non-evasive way that can leverage the company’s existing chat functionalities. To do that, it will establish a reputable in-app C2C market called Bazaar, allowing users to buy and sell goods in their local area. WhatsApp will charge a small fee for each posting and integrate existing P2P payment apps like Venmo and PayPal for transactions.

All users by default already go through one level of verification, which is their phone number (required for all WhatsApp accounts) for extra buyer-seller protection. Bazaar will be an added benefit for existing WhatsApp users who prefer the communication platform over a social media outlet with less security and privacy.

Exploring the C2C Space

I took a look at direct competitors in the online marketplace realm and compared available features. Indirect competitors include small businesses and have product shipping options that I won't be covering in the first version of this feature due to logistical complexities, but I was interested in seeing how they tackled product listing pages and filters.


Basic Chat Functionality

Apps like LetGo and OfferUp have a very basic chat feature built in for text messages used only within the app. Facebook Messenger can store Marketplace messages, but it exists as a separate app. Alerts on the native FB app are easily missable, as they exist alongside all other notifications (ex. birthdays, events, status updates, etc).

No Consistent Filters

Each selling app has different filters that are not entirely comprehensive. Some might be missing parameters for condition, seller rating, or delivery methods.

Ambiguous Payment Methods

Currently there is no way of knowing or filtering by accepted payment methods for each seller unless it is explicitly stated in the product description. Facebook Marketplace is the only app that accepts payment via credit card or PayPal.

Poor Handling of Multiple Items per Listing

Listings with multiple products for sale feature photos that are lumped together, often lacking descriptions or pricing that are itemized. 

Understanding Current Buyer/Seller Behavior

To learn more about motivations behind usage of certain selling apps, as well as how transactions are usually handled, I interviewed and shadowed 5 users who are either buyers, sellers, or both. Participants shared their phone screens and showed me how they normally browse for items and communicate during transactions.


Temporary Buying/Selling Apps

Users download multiple selling apps to reach a wider audience or see more search results. Sellers deleted their apps after they have nothing more to sell (usually following a purge, like when moving). WhatsApp differentiates itself by being primarily a chat app that users can keep around regardless of whether they have something to sell.

Selling Multiple Items

Users stated that listings with multiple items sometimes are labeled "Free" to encourage clicking into the listing. Buyers would negotiate for lower prices if buying multiple items from one listing, or the seller would offer a discount. Sellers would prefer to put multiple items under one listing as it is easier to manage. However, they have to type out the item number or include a link to clarify which one they are referencing. 

Alternative Payment Methods

Currently users deal mostly with cash transactions, but they would like to use other payment methods. For sellers, offering more payment options can increase audience reach. They are also easier to track than cash.

Determining the Legitimacy of Buyers/Sellers

It is important for users to see if a buyer/seller is reputable. They would like to see a real profile picture, reviews, ratings. 

Narrowing Down Search Results

When users cannot find what they are looking for, they change their search terms to be more specific. Sometimes they would narrow down by categories, but this isn't always accurate as sellers might incorrectly categorize items.

Privacy is Important

Users don't want their listings to be broadcasted to their contacts or to share their phone numbers.

02 Define

Different Use Cases

Through user interviews, I identified three personas based on their motivations for buying and/or selling. Separate user flows were created for each based on their unique use cases.


Looking for a Specific Item

Kenneth exhibits the most common buyer behavior amongst users I interviewed: knowing exactly what he wants, and looking for it on WhatsApp Bazaar. The deciding factor on purchases will boil down to which listing is the most affordable.

Temporary Purging

On the seller side, Zoey is looking to get rid of many items at a time, likely due to a major life event (ex. moving). This user is more likely to offer bundle prices for multiple sales so she can move products as quickly as possible.


Frequent Buying / Selling

Prima is more of a casual buyer/seller who would use WhatsApp Bazaar from time to time as items accumulate in her home, or if she is looking to change up her environment. Since she does not always have a specific item in mind, a comparison tool can provide inspiration for other listings she might be interested in.

Identifying Needs and Pain Points

I created a user journey map to empathize with the customer from the buyer's perspective on what they experience before, during, and after using Bazaar. Most negative emotions concern aspects of the shopping process that are more unpredictable, such as quality of search results and communication with buyers/sellers. I will focus on optimizing these experiences.


Creating Top-Level Categories

I was interested in seeing how users organized top-level categories in a space as complex as an online marketplace, which can have a huge variety of items.

I conducted a remote open card sort with 10 participants using Trello. There are 75 unsorted cards for them to categorize, all items found from real online marketplaces.

Overall, categories such as Vehicles, Electronics, Hobbies and Clothing and Accessories mirrored existing marketplaces. However, there were other notable distinctions such as separation between what goes in the home and what is outdoors, renaming “Classifieds” to “Services,” and including unique “Gift,” “Sports / Exercise,” and “Furniture” categories.

For this first iteration of Bazaar, I want to focus on physical items that can be picked up or delivered, and so removed housing, services, and vehicles.


Finding a Place for Bazaar Within WhatsApp

I created a site map to show how Bazaar lives within the information architecture of WhatsApp. It is still primarily a chat app, so I corralled all shopping activities within the Bazaar section. The only exception would be buyer-seller conversations, which are found in the Chat section. This makes it easier for users to access new Bazaar messages in an area of the app they already frequent.

03 Ideate

Mapping Out Three Core Activities

Bazaar consists of three main experiences - browsing for an item, selling items, and communicating between buyers and sellers. I began by sketching low-fidelity wireframes to quickly visualize relationships between screens. Doing this exercise helped act as a foundation for developing user flows later on. A simple color dot system shows which screens are interconnected.


Tackling Low Points from the User Journey

For the first round of designs, I want to focus on two main activities (browsing for an item, and communicating with buyers/sellers) as these were the low points found in my user journey map. I also wanted to explore how a comparison tool would work to further enhance browsing. A design system already exists for WhatsApp, so I was able to jump directly to high-fidelity wires after developing these user flows.

04 Prototype


Verification and Privacy

Users can see a buyer/seller's rating and reviews, but it will not link through to their personal profiles. All messaging is done within WhatsApp, but the option to call will only be available to existing contacts to protect user privacy.

Complete Transactions within One App

Leveraging WhatsApp's existing chat functionality, buyers and sellers can easily share meetup locations, send additional photos, and be notified of new messages. Now they can also pay with integrated Venmo and PayPal options, as long as both parties have linked accounts.


Two Chat Streams

In order to maintain WhatsApp's core purpose of enabling chats between friends and family, I separated these "General" groups from "Bazaar" communications. Users can easily toggle between the two without confusion of which is personal or business-related.

Selling Multiple Items

Users from earlier interviews stated they would offer bundle prices to buyers interested in multiple items. To make upselling even easier and help with memorability, I added an option that allows them to reference an item from their listing through a dropdown. They can then send a direct link to the item through the chat window without having to go back to the original listing page.


Making the Comparison Tool Dynamic

I created a dynamic comparison tool that gives the user more control over what they would like to see more of. Similar to a filter, users can narrow down results based on price, distance, seller rating, condition, or product description keywords relative to the base item they are comparing against. Instead of scanning a chart to compare features of similar products, they can now dictate which attribute is most important to them. This tool is especially helpful for users who do not have a specific product in mind.

05 Testing

Pinpointing UI Improvements

For the first round of usability tests, I used Maze, an unmoderated remote testing tool, to get some quick feedback on the UI and for proof of concept from 9 users. With heat maps and user flow tracking, I completed some rapid usability fixes before conducting more in-depth testing where users would reflect more on actual use cases:

  • Display prompt to select a location after exchanging messages about meeting up and a prompt about paying after they announce they are on location.

  • Give users the flexibility to choose a location or post a picture by clicking on prompts, selecting its respective icon, or clicking the "+" pop up menu.

  • Bring down the dropdown for additional items so it is closer to the user's eye level (by the keyboard).

  • Include an alternative route to the Chat windows from Bazaar so users do not have to navigate back to the home screen to access the Chat feature. Overtime, users will learn that they don't have to go back to Bazaar to access their buying/selling-related chats.

  • Create clear distinction between base item that is being compared and similar products.

Comparing to Real World Situations

In my second round of usability tests, I observed 5 users interacting with the mobile prototype and asked for feedback on how the design compares to their actual real-world experience using WhatsApp or buying/selling.

Raising Awareness for a New Feature

Users did not immediately notice the "Bazaar" tab in the main Chat section, even though the placement follows existing UI for Broadcast Lists (perhaps a seldom-used feature). There will have to be some onboarding when this new feature rolls out. But they noted that they liked separating their main chats with friends and family from Bazaar-related messages.


Filters are Helpful

Although categories were not the go-to solution for users who know what they're looking for, they did find filters helpful and suggested additional parameters they'd like to see included, such as seller rating and delivery options.

Clarifying the Comparison Tool

There was some confusion surrounding the comparison tool due to lack of context for its filters. In the redesign, I included parameters so users can customize their specifications.


More Integrations for Transactions

Users liked being able to select meetup locations, pay, and share photos of items through the chat window. They would also like to schedule meetup dates/times and add them to their phone or Google calendars.


Searching for Specific Items vs. Browsing

Through usability tests, participants expressed that they would normally already have an item in mind when using online marketplaces. They are more likely to input a search query directly than browse categories. However, sometimes their search terms bring up irrelevant items. In this case, they will narrow down results by tapping into specific categories.

Initially, users were confused by seeing categories underneath the search bar and were under the impression that they must select a category along with their query. In a later iteration, I separated the categories so it is more obvious that narrowing down results is optional.

Learnings & Next Steps

Seller Dashboard

For future iterations, I'd explore how the Seller Dashboard would look and how settings in there can help facilitate buyer/seller communication further. For example, confirmation of agreed-upon amounts for each listing protects sellers from being further low-balled during in-person meetings. Sellers should also be able to pre-select a number of meeting locations and pickup dates/times, which buyers can view to reduce the amount of back-and-forth. Additionally, sellers would receive reminders to update the status of their listings after a period of inactivity to ensure items posted are still available.

Success Metrics

All WhatsApp transactions are encrypted. However, we can measure the number of listings and unique sellers over a three-month period to test the adoption rate. For buyers, we can measure engagement based on the number of total impressions on listings. For qualitative feedback, we will read through customer reviews.