Load JSON from disk

"Load JSON from disk" is a fine name, but the url input trips up every first-time user, because it's not a web URL at all. This node reads a JSON file straight off your machine and turns it into a JSON object you can pipe into the rest of your graph. It's the read half of LF Nodes' file I/O story - pair it with the JSON manipulation nodes and you can load config files, LoRA test datasets, or wildcard lists without hand-typing them into a string node.

The one field that matters is url, and the format matters. On Windows it looks like file://C:/myjson.json; on Linux or macOS it's file:///home/you/data.json - note the extra slash after file: on Unix paths. Missing that third slash is the classic "why won't it load" moment. There's a second input, ui_widget, but that's LF's house style: a widget the frontend uses to render the value as a collapsible tree, not something you wire anything into.

Output is a single JSON port. From there it plugs into the rest of the LF JSON family - LF_GetValueFromJSON to pull a field out, LF_SortJSONKeys or LF_ShuffleJSONKeys to rearrange it, or straight into any node that accepts a JSON object. Because the output type is LF's own JSON type, you'll mostly be wiring it into other LF nodes or into workflows that already use this pack.

Install is the standard LF Nodes route: ComfyUI Manager → search "LF Nodes" → install and restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/lucafoscili/comfyui-lf

Restart ComfyUI and you're done - no model downloads, no Python dependency roulette. This is a data node, not a generation node.

Two things worth knowing before you build around it. First, it reads the file at execution time, so if you edit the JSON on disk and re-run the workflow you get the fresh content - no cache to clear. Second, a heads-up on the pack itself: comfyui-lf went into legacy mode in February 2025, frozen and fully functional, while the author moved active development to the renamed lf-nodes repo. Your existing workflows keep running here; when you start fresh, install the new repo instead and the same node is waiting for you there.