RIVR: The Stair-Climbing Robot Amazon Just Acquired

RIVR: The Autonomous Delivery Robot That Climbs Stairs and Got Acquired by Amazon

Most delivery robots stop at the kerb. They roll along flat paths, reach the front gate, and wait. The last 30 metres — up the steps, to the actual door — still belongs to a human. That gap is exactly what RIVR was built to close. On March 19, 2026, Amazon decided the solution was worth acquiring entirely.

RIVR is a Zurich-based robotics company building autonomous delivery robots powered by General Physical AI. Founded in April 2023 as a spinout from ETH Zurich's Robotic Systems Lab, it started as Swiss-Mile before rebranding in January 2025. The robot combines four articulated legs with wheels at each endpoint. On flat ground, it drives at up to 15 km/h. When terrain gets complicated — stairs, kerbs, uneven paths — it switches to walking. Throughout, it carries payloads of up to 60 kilograms directly to the door without human help.

How the Autonomous Delivery Robot Physical AI System Learns

The intelligence behind RIVR is what separates it from every flat-ground sidewalk bot before it. Physical AI combines neural networks trained through reinforcement learning and physics-based simulation, developed in close collaboration with NVIDIA. Every real delivery generates new data. Moreover, each delivery makes the AI sharper than the last.

Marko Bjelonic, co-founder and CEO, was the first researcher to apply artificial neural networks to wheel-legged locomotion during his PhD at ETH Zurich. His foundational research is the engine behind RIVR's commercial robots today. Furthermore, just before the acquisition closed, RIVR launched RIVR TWO — its second-generation robot, more capable and more refined than anything previously deployed.

From Zurich Streets to Amazon: The Last-Mile Autonomous Delivery Robot That Delivered

The robot proved itself on real streets with real customers. In Zurich, RIVR partnered with Just Eat Takeaway.com, letting customers select robot delivery through the JET app and retrieve orders via QR code. In May 2025, it launched with Veho in Austin, Texas. In early 2026, it went live in Milton Keynes, UK. Three cities. Three countries. All live, revenue-generating operations.

RIVR raised $25 million in total. Its $22 million seed round in August 2024 was co-led by Jeff Bezos through Bezos Expeditions and HongShan, with the Amazon Industrial Innovation Fund also participating. Consequently, when Amazon acquired the company outright in March 2026, it was deepening a relationship it had already backed twice.

The global last-mile delivery market surpassed $155 billion in 2024, growing at 8.4% annually through 2032. The bottleneck has never been the van. It's the walk from the van to the door — where drivers spend the most time covering the shortest distances. RIVR was designed to own that walk, returning those minutes to drivers and reducing physical strain across a workforce where final-stage injury rates remain high.

Three years from ETH Zurich lab to Amazon acquisition. That's what Physical AI looks like when the real world confirms it works.