SelectBbox

A detector rarely finds exactly one thing. SelectBbox is the node that turns "here's a list of N boxes" into "here's the one box I actually want," picked by a plain numeric index.

The inputs and outputs that matter

• index (INT, default 0, range 0–50) - which position to pull out.
• bboxes (BBOX, optional) - a native bbox list, typically from an upstream detector or this pack's own bbox nodes.
• bboxes_json (STRING, optional) - a raw JSON alternative, useful if the box coordinates are coming in from outside the graph entirely - say, directly in an API request body - rather than from something already running inside ComfyUI.
• bbox (BBOX) - the single box at index.

Wire in whichever of the two optional inputs you actually have; index then pulls the entry at that position out as a single box.

Where you'd actually use it

The natural next step after this node is MaskByBboxes (feed the selected box in as the collection to paint a mask from) or CropImageByBbox elsewhere in this pack, if all you want is that one detected region isolated from the rest of the image - the same detect-crop-refine shape that drives most region-specific editing.

How to install it

Via ComfyUI Manager: search comfyui-easyapi-nodes, install, restart. Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/lldacing/comfyui-easyapi-nodes.git
cd comfyui-easyapi-nodes
pip install -r requirements.txt

Restart ComfyUI. No models needed.

Common issues & troubleshooting

index tops out at 50. That's a hard ceiling baked into the node's own schema, not an arbitrary UI limit - if a detector genuinely returns more than 51 boxes, anything past index 50 isn't reachable through this node's slider as it stands.

Leave both bboxes and bboxes_json unconnected and there's nothing to select from. Exactly one of the two needs to actually be wired or filled in for this node to do anything - an easy thing to miss if you copied this node in from a template workflow and left a placeholder wire disconnected.

If both happen to be connected at once, treat that as a configuration mistake rather than a deliberate fallback - this node's job is picking one item from one collection, and having two possible sources wired in simultaneously is exactly the kind of ambiguous setup worth cleaning up before you rely on the output, rather than trusting whichever one happens to win.