app.py

from fastapi import FastAPI, UploadFile, File
from fastapi.responses import Response
from rembg import remove, new_session

app = FastAPI()

# Create ONE session (cached in memory)
SESSION = new_session(
    "u2net",
    alpha_matting=True,
    alpha_matting_foreground_threshold=240,
    alpha_matting_background_threshold=10,
    alpha_matting_erode_size=10,
)

@app.get("/")
def health():
    return {"status": "ok"}

@app.post("/remove-bg")
async def remove_bg(file: UploadFile = File(...)):
    input_bytes = await file.read()

    output_bytes = remove(
        input_bytes,
        session=SESSION
    )

    return Response(
        content=output_bytes,
        media_type="image/png"
    )