I was looking for an affordable way to use Invoke AI in my mobile office, as I don't have a powerful PC with an Nvidia graphics card there. Unfortunately, I couldn't find anything suitable. However, there seem to be two websites where you can use ComfyUI for free (untested):
According to the price list, the starter version of ComfyUI Cloud is free. However, without registering, it's impossible to see what features it offers.
On the Comfyai Run website, however, you can download a large number of free workflows even without registration.
Here too, the starter version is free according to the price list. To decide whether registering on one (or both) sites would be worthwhile for me, I saved the workflow for creating SDXL images locally.
To do this, first go to "Browse Templates" in the upper right corner and select a workflow. Then, click on "Workflow" in the upper left corner and then on "Download".
Since I already have several checkpoints on my computer, I only needed an SDXL refiner to execute the workflow.
Then I selected a checkpoint from the drop-down list and the refiner (which also needs to be copied into the comfyui>models>checkpoints folder).
The initial tests looked quite good. I'll run a few more tests to see if a mobile online version of ComfyUI is of interest to me or not.
Addendum: The free basic version only includes the basic software. It doesn't include custom LoRAs or checkpoints. Therefore, it's not of interest to me.