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The world’s largest fashion resales marketplace
San Francisco, California, USA
2018 – till now
  • Fasion
  • /
  • California
  • /
  • 2018

E-commerce store


Ruby on Rails, React.js, Redis, Sidekiq, RSpec,
Postgres 11

thredUP is the world’s largest fashion resales marketplace. The platform allows to buy and sell women’s and kid’s apparel, shoes, and accessories globally.

The platform promotes the idea of a sustainable fashion future by making it easy to buy and sell women’s and kids’ secondhand apparel, shoes, and accessories.

With the support of world-class investors, thredUP has developed a powerful resale engine that has already distributed over 100 million unique clothing items. Currently, the company is working on introducing the resale to a broader fashion industry through their resale-as-a-service (RAAS) platform.

At the beginning of 2022, the thredUP platform raised a fantastic $168 million with its initial public offerings, or IOP for short. It achieved a valuation of almost $1.3 billion. Apart from that, the company succeeded in selling 12 million shares at $14 apiece.

The core idea behind the fashion resale marketplace thredUP

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1 /
Reduce fashion waste and extend the life of clothing items by means of responsible recycling and resale.
2 /
Sell donated items as soon as possible with the help of personalized marketing and complex algorithms.
3 /
Allow consumers to buy and sell secondhand clothes in a fast and convenient way.
4 /
Help a new generation of consumers embrace a more sustainable future.
5 /
Educate consumers about the fashion waste crisis.

Project history

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The customer is a well-established business founded in 2009. The co-founder and CEO of thredUP Inc., James Reinhart, had a noble mission of bringing innovation into retail, the apparel industry, and the environment. So he decided to build a platform where consumers could sell gently used items they no longer needed or wore.

thredUP is a complex technology solution. Its technology stack includes many advanced proven programming languages, frameworks, and tools. They are PHP, Node.js, Ruby, and Ruby on Rails. The latter has become the main backend technology that made the company’s operations scalable, automated, and streamlined.


Required team extension

With the company’s growth, James Reinhart felt the need to expand his Ruby on Rails development team. After careful consideration, he found outsourcing his project to some remote development team the most suitable option. 

The primary search criteria was profound knowledge of Ruby on Rails technology. Apart from that, having a development team ready to take on their project was a deal maker for thredUP’s owners.

Our current customer recommended Syndicode as a reliable software development company focused on building custom marketplaces with Ruby on Rails. 

James Reinhart came to our office in Kyiv to have a personal meeting with our development team. As a result of this meeting, thredUP hired several dedicated Ruby on Rails developers from Syndicode for full-time employment.

Ruby on Rails services provided by Syndicode

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In a few months, a supply engineering team was created. Thus, our developers became fully valid members of the thredUP project.

We focused on building and modifying the functionality for buyers. The biggest technical challenge our software development team had was related to the legacy code that we had to optimize and rewrite.


On the thredUP platform, suppliers can order a clean-out kit with the shipping label. It is a plastic bag that sellers fill with clothing items they no longer need and send back to thredUP. The company processes these orders, sells the items, and provides suppliers with payouts.

Our development team was responsible for improving this workflow. The aim was to improve the conversion rate so that sellers do not leave the website during the ordering process. To be more specific, we remade the filling form, which was very cumbersome and complicated. We reduced the number of steps users should take to make the form more convenient and user-friendly.

Apart from that, we provided sellers with an opportunity to generate online labels instead of ordering a physical bag. They can print these labels and stick them to their own bags or boxes that will be further sent to thredUP. As soon as the package arrives there, the staff members will scan the barcode and assign this parcel to a certain user. We optimized this workflow to make it fully automated.