BackgroundTasks

A collection of background tasks to be executed after sending a response to the client.

BackgroundTasks

A collection of background tasks that will be called after a response has been sent to the client. This is useful for operations that need to happen after the request but don’t need to block the response, such as sending emails, processing data, or logging.

from fastapi import BackgroundTasks, FastAPI

app = FastAPI()

def write_notification(email: str, message=""):
    with open("log.txt", mode="w") as email_file:
        content = f"notification for {email}: {message}"
        email_file.write(content)

@app.post("/send-notification/{email}")
async def send_notification(email: str, background_tasks: BackgroundTasks):
    background_tasks.add_task(write_notification, email, message="some notification")
    return {"message": "Notification sent in the background"}

Methods

add_task

Add a function to be called in the background after the response is sent.

def add_task(
    func: Callable,
    *args,
    **kwargs
) -> None

func · Callable · required

The function to call after the response is sent. It can be a regular def function or an async def function.

*args · Any

Positional arguments to pass to the function.

**kwargs · Any

Keyword arguments to pass to the function.

Usage Notes

• Background tasks are executed after the response has been sent to the client
• Both sync (def) and async (async def) functions are supported
• Tasks are executed in the order they are added
• Multiple tasks can be added to the same response
• Background tasks run in the same process, so they’re suitable for lightweight operations

Learn More

Read more in the FastAPI docs for Background Tasks.