Rebrickable

Users on Rebrickable are able to sell and distribute instructions for custom builds, known as MOCs (My Own Creations), with the buyer acquiring parts elsewhere to build it. Creations uploaded to the website include alternate builds, which reuse parts from existing sets. The website also contains a database with information about different Lego sets and parts, with users being able to see what MOCs they can design with their current Lego collection.

Rebrickable was founded by Nathan Thom in 2011; initially, it was primarily meant to index Technic sets. Thom told Popular Mechanics in March 2020 that "I began Rebrickable because I had thousands of pieces I collected from sets and wondered if there was something else, already designed, I could build with them". The website went through major updates in 2014 and 2017, respectively. In 2017, a similar platform known as MOCPlans merged with Rebrickable after it was shut down. Bricksafe, a sister website for file hosting, was created in 2013.

The website hosted over 15,000 MOCs by 2020, and as of 2026, it now hosts almost 200,000. According to the Australian Financial Review, designs for ships, trains and large buildings are particularly popular.

Rebrickable's data on Lego sets is crowdsourced, with a team of administrators attempting to ensure its accuracy and reliability. Among the projects developed by them is RebrickNet, an artificial intelligence system for detecting Lego parts in photos.