Product Engineer Backend, Global Supply

In the Marketplace business, we aim to realize a global marketplace that creates new value—driving the growth of diverse businesses through the creation of customer value.

Starting with the operation of Mercari, Japan's largest flea-market service, we advance the Mercari Group's mission through our cross-border business and various new ventures.

We’re building a single commerce foundation shared across all Mercari marketplaces, rather than separate foundations for each business and country.

As part of the team, your mission will be to realize our global marketplace—enabling both individual sellers and businesses to list items that customers worldwide can buy with ease and confidence.

Under a development structure that assumes AI, we pursue both the delivery of customer value and maximum speed at the same time.

Engineers in this position are expected to act as Product Engineers (PdE), taking end-to-end responsibility from specification through the completion of delivery.

You will not be confined to your own area of expertise, and are expected to cross boundaries in order to solve problems.

From the Definition phase onward, you'll take the initiative and autonomously lead specification concretization, alignment, quality and measurement, release, and the operations that follow.

As a Product Engineer (PdE), you will take end-to-end accountability for Global Supply — from shaping specifications through production release and the operations that follow — working closely with a Product Manager and other stakeholders.

Across all of this, you'll be building for more than the first market — from how items get listed to how customers worldwide reach them, what you ship should hold up for the next country without being rewritten.

Start from working prototypes: use running code to settle open questions and finalize specifications, and lead implementation across services and platforms

Establish measurement (events, logs, dashboards), quality bars, and phased rollout plans, and carry changes through production release and the operations that follow

Decide what belongs in the shared foundation versus what stays specific to a market, and when to extend what exists versus build new

A range of tools centered on Claude are available

We expand and change the models and tools we offer on an ongoing basis, in line with requests and industry trends

Mercari's marketplace grew up in Japan, and much of what powers it today was built for Japan. This area is about shaping the foundation for a genuinely global marketplace — one designed from the start for multiple markets, languages, currencies, and regulatory environments rather than retrofitted for them.

That runs all the way down to how listing itself works: it has to stay effortless for someone selling a single item, work just as well for a business listing at scale through an API, and still produce data structured enough to power search, pricing, and recommendations in every market.

Global demand is growing faster than the supply available to serve it, which puts this area directly on the critical path for growth.

There is a short and visible line between what you ship and how much selection customers around the world can actually reach — and the foundation underneath it doesn't stop at supply.

Much of this is still undecided: where the boundary sits between what's shared globally and what stays specific to a market, what to build new versus what to carry forward, and which problems to solve first.

We're also asking what changes when AI agents, not just people, are listing and buying.

You'll be part of deciding, not handed the answers.