Thumbor

Thumbor is an open-source smart imaging service that provides on-demand image cropping, resizing, and flipping capabilities. While not strictly an AdTech company, Thumbor plays a significant role in the digital advertising ecosystem by enabling publishers, advertisers, and ad tech platforms to dynamically optimize and serve images at scale. The service is particularly valuable for responsive ad creative delivery, where images need to be automatically adjusted for different screen sizes, devices, and placements without manual intervention. Originally developed by Globo.com (a major Brazilian media company), Thumbor has become a widely-adopted open-source solution used by media companies, e-commerce platforms, and digital publishers worldwide. Its ability to process images on-the-fly makes it especially useful for programmatic advertising environments where creative assets need to be optimized in real-time for various ad formats and placements. The project is maintained by a community of developers and has spawned various commercial implementations and hosting services built on top of the core technology.