Save Image with Metadata

The built-in Save Image already embeds your workflow in the PNG - that part is automatic and it's the whole basis of ComfyUI's sharing culture. What it won't do is save anything you want to say beyond that. Save Image (Metadata) is a drop-in replacement that writes your own custom metadata into the file, alongside the usual prompt and workflow chunks.

Reach for it when you want the output to carry extra baggage: which model and sampler you used, LoRA names, a CivitAI-style "parameters" string, or a note to your future self about what worked. Because it lands in the PNG's text chunks, it survives sharing - whoever downloads the image can read it back with this same pack or any PNG-info viewer.

How it works

It takes the image tensor and a metadata text, then writes the PNG with PngImagePlugin.PngInfo: the normal ComfyUI prompt and workflow chunks from the hidden prompt/extra_pnginfo inputs, plus your custom metadata as its own chunks. If you pass valid JSON, each key/value becomes a chunk and non-string values get JSON-serialized. If the text isn't valid JSON, the whole thing lands under a single UserMetadata key - so plain text works fine, it just gets a generic label.

The neat bit: leave metadata_text empty and it looks for the _metadata attribute riding on the tensor, set by Load Image (Metadata) or Set Image Metadata. That's the pack's headline feature - set it upstream, save it here, never type the same string twice.

Inputs that matter

• images - what to save. Accepts a batch.
• metadata_text - optional. A JSON object or plain text to embed. Empty means "inherit from the tensor."
• filename_prefix - default "ComfyUI", same counter/numbering behavior as core Save Image.

No outputs - it's an output node, and it reports the saved files back to the UI.

Installing

ComfyUI Manager, search "Metadata Tools", install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/0nikod/ComfyUI-Metadata-Tools

Restart afterwards (plus pip install -r requirements.txt if the environment insists). Two notes: the README's own clone URL is typo'd - it reads dniko0/ but the repo is 0nikod/ - and the only declared dependency is Pillow, which ComfyUI already ships. No models, no heavy deps.

Troubleshooting

• Your custom metadata didn't appear. The usual cause is the tensor losing its _metadata attribute somewhere upstream - any node that clones, cats, or rebuilds the tensor drops it silently. Fix: pass metadata_text explicitly instead of relying on the attribute.
• You passed a JSON array and it saved as one Metadata chunk. The node only expands JSON objects; arrays and numbers get stashed whole. Pass a dict.
• The workflow still saves regardless. The prompt and workflow chunks are always written, so this node is strictly a superset of Save Image - you can't accidentally strip the workflow by switching to it.