Five years after launch, the Marketplace Tab on Facebook now has over a billion monthly active users, more than Snapchat and Twitter combined.

in many early research studies, more than half of people studied in many countries cited Facebook as a place they had bought or sold things. This was less common in Western markets, which made it a blind spot for many of those at the company.

Kids generate a lot of used goods, many of which are insanely expensive to buy new. I also had friends in Asia who talked about how meaningful buying and selling in groups was to them, and how Facebook was the place to connect for commerce.

We decided to set up a way to allow group admins to opt into becoming classified commerce groups. This allowed us to track organic behaviors on the platform.

We also started to rank the group content to help people discover products for sale. Prior to this, no group content was ranked—it was purely chronological.

We evaluated a number of options for building the V1, balancing speed and functionality, and decided to use React Native, one of the first major products to do so. This enabled us to build nearly twice as fast, at the cost of flexibility.

Our early bet was that supply would drive demand—that having sufficient inventory would get buyers excited about coming to this new tab to browse. To do that, we had to get sellers on board.

A small bug in the fraud queues resulted in a massive flood of violating items.

1. Focusing on trust

Buying and selling face-to-face meant that trust was a huge factor, especially when it came to bulky items that required people to meet up in person.

He felt more comfortable seeing their real identities and the duration they had been on the Facebook platform, something that wasn’t possible on other, anonymous platforms.

3. Integrating with Messenger

Being integrated with Facebook Messenger makes communication fast and easy. It allows you to pin your location and have someone come to you, or easily send a deposit to someone.

4. Leveraging the Groups community

This idea of people-powered commerce, buying from your neighbors, and reducing waste was part of the ethos of the product from the start.

1. Follow the data

Knowing someone had mutual friends or had been active on Facebook for over a decade provided confidence to those who were looking for someone to live with. The same goes for car selling: Trust is important, since you are meeting and getting into a car with a stranger.

Following the data, we were able to iterate and evolve the product to be what users were looking for.

2. Device matters

While the product started primarily for mobile, we realized that to be competitive, we needed to add a desktop version. This was important for larger purchases and would make listing easier for high-volume sellers.

3. Navigating scaling

To address both violations and transaction measurement, we settled on encouraging buyers and sellers to report transactions by incentivizing ratings and reviews.