# Request timeouts | Modal Docs

- **URL:** https://modal.com/docs/guide/webhook-timeouts
- **Summary:** Handle long-running Web Function requests on Modal with automatic redirects and polling patterns for results.

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Request timeouts
================

Web Function requests should complete quickly, ideally within a few seconds. All Web Function types ([`modal.fastapi_endpoint`](https://modal.com/docs/sdk/py/latest/modal.fastapi_endpoint)
, [`modal.asgi_app`](https://modal.com/docs/sdk/py/latest/modal.asgi_app)
, [`modal.wsgi_app`](https://modal.com/docs/sdk/py/latest/modal.wsgi_app)
, and [`modal.web_server`](https://modal.com/docs/sdk/py/latest/modal.web_server)
) have a maximum HTTP request timeout of 150 seconds enforced. However, the underlying Modal Function can have a longer [timeout](https://modal.com/docs/guide/timeouts)
.

In case the Function takes more than 150 seconds to complete, an HTTP status 303 redirect response is returned pointing at the original URL with a special query parameter linking it that request. This is the _result URL_ for your function. Most web browsers allow for up to 20 such redirects, effectively allowing up to 50 minutes (20 \* 150 s) for Web Functions before the request times out.

(**Note:** This does not work with requests that require [CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS)
, since the response will not have been returned from your code in time for the server to populate CORS headers.)

Some libraries and tools might require you to add a flag or option in order to follow redirects automatically, e.g. `curl -L ...` or `http --follow ...`.

The _result URL_ can be reloaded without triggering a new request. It will block until the request completes.

(**Note:** As of March 2025, the Python standard library’s `urllib` module has the maximum number of redirects to any single URL set to 4 by default ([source](https://github.com/python/cpython/blob/main/Lib/urllib/request.py)
), which would limit the total timeout to 12.5 minutes (5 \* 150 s = 750 s) unless this setting is overridden.)

Polling solutions 

Sometimes it can be useful to be able to poll for results rather than wait for a long running HTTP request. The easiest way to do this is to have your web endpoint spawn a `modal.Function` call and return the function call id that another endpoint can use to poll the submitted function’s status. Here is an example:

    import fastapi
    
    import modal
    
    
    image = modal.Image.debian_slim().pip_install("fastapi[standard]")
    app = modal.App(image=image)
    
    web_app = fastapi.FastAPI()
    
    
    @app.function()
    @modal.asgi_app()
    def fastapi_app():
        return web_app
    
    
    @app.function()
    def slow_operation():
        ...
    
    
    @web_app.post("/accept")
    async def accept_job(request: fastapi.Request):
        call = slow_operation.spawn()
        return {"call_id": call.object_id}
    
    
    @web_app.get("/result/{call_id}")
    async def poll_results(call_id: str):
        function_call = modal.FunctionCall.from_id(call_id)
        try:
            return function_call.get(timeout=0)
        except TimeoutError:
            http_accepted_code = 202
            return fastapi.responses.JSONResponse({}, status_code=http_accepted_code)

[_Document OCR Web App_](https://modal.com/docs/examples/doc_ocr_webapp)
 is an example that uses this pattern.

[Request timeouts](https://modal.com/docs/guide/webhook-timeouts#request-timeouts)
[Polling solutions](https://modal.com/docs/guide/webhook-timeouts#polling-solutions)