Games that use Vulkan can now use FSR 4 upscaling thanks to the latest OptiScaler
A third-party tool, OptiScaler, has beaten AMD to the punch in using FSR 4 upscaling with Vulkan-based games. According to a changelog on the tool's Discord server, the latest test build, v0.9.0-pre10, has "added Vulkan w/Dx12 support – FSR4 VK w/Dx12, FSR 2.1 VK w/Dx12" (via Reddit user eduhfx).
OptiScaler lets you expand the number of upscaling and similar features that are available to hardware, which aren't officially natively supported in many games. Such that, for instance, you can force FSR 4 in games that say they don't support it for your hardware. Installing it involves pasting files into your game installation folders and sometimes modifying batch scripts.
The third-party tool has been used for quite some time now, with even AMD RX 9000-series gamers using it throughout the first half of 2025 to get FSR 4 working in many games where there wasn't an official implementation. Since then, AMD has given FSR 4 support to additional games, but only ones that already supported DX12 and FSR 3.1.
Notably excluded from that roster of games are Vulkan ones, because FSR itself doesn't work with this graphics API. OptiScaler steps in once again, as it did to help with initial FSR 4 support in DirectX games, bypassing the whole problem by using a system where the upscaling instructions are processed via DirectX 12, instead of Vulkan.
It's somewhat of a point of contention with many AMD gamers that the GPU manufacturer hasn't done more to actually implement its latest and greatest features, such as FSR 4 and Redstone, into games, leaving gamers to use OptiScaler instead.
One of the main draws to Vulkan is that it's cross-platform; you'll see plenty of games running on the API if you switch over to Linux for that reason. OptiScaler doesn't run natively on Linux, but you can get it working through Proton and Mesa with a little work.
This added support won't just be useful for Linux gamers, though. Some games are exclusively or primarily Vulkan, such as Doom Eternal, and Vulkan is sometimes more performant than DX12, especially on older hardware.
Given FSR 4 is just objectively better than previous versions, especially when it comes to image quality, this should be a nice update for many who aren't squeamish about messing with game files and the like. It might still be a little behind Nvidia's solution, DLSS 4.5, but it's almost closed that gap. Which is why it's frustrating that support is so limited. Well, officially, at least. Thanks be to OptiScaler.