FastAPI + OCR Pipeline: Should You Use BackgroundTasks or Celery? A Complete Guide

FastAPI + OCR Pipeline: Should You Use BackgroundTasks or Celery? A Complete Guide You've just deployed your document processing system, and everything works great—until your first user uploads a 50-page scanned document at 2 PM on a Tuesday. Their browser hangs. Your FastAPI server is locked up. And you're frantically googling whether you made a terrible architectural decision. Welcome to the real-world challenge of building async document processing systems. I've been there, and I'm going to walk you through exactly how to avoid this situation—and when to know it's time to level up your infrastructure. The Root Cause: Why This Matters Here's the thing about OCR processing: it's computationally expensive. Whether you're using Tesseract, EasyOCR, or a more sophisticated solution, you're looking at CPU-intensive operations that can take anywhere from 2-30 seconds per document. In a traditional synchronous architecture, this would completely block your server, making it unable to handle