Nissan and Honda's merger collapsed last year, but they're working together in a new way.

The two companies announced they would develop common computers and operating systems for software-defined vehicles.

Vehicles on these new platforms should roll out starting in 2029, the companies said on Monday.

It's finally happening: Honda and Nissan are officially joining forces. The Japanese automakers nearly merged, but those negotiations fell through last year. Now the companies have announced concrete plans to work together on software-defined vehicles, as they both work to combat what's coming out of China and Silicon Valley.

On Monday, the companies said they have entered into a joint development agreement to standardize core electronic control units (ECUs), vehicle operating systems, middleware, and vehicle control software for future vehicles. Specifically, the ECUs include high-performance main computers and zonal ECUs that control specific areas of the vehicle.