Hi guys, Just wanted to give you a heads up that yesod's sendFile is not setting the Content-Length header, which 'breaks' some proxies and load balancers. (in our case, amazon elastic load balancer). I don't know if that's by design, I'm not 100% sure but not setting the header would be only useful for 'long pooling' of binary files for doing some sort of hackish http streaming, which I don't think is yesod's purpose anyways :) A workaround is setting the Content-Length header before calling sendFile, I guess it may be something easy to add, I was going to propose a patch that just wraps the current implementation in a do block that sets the header, but then I noticed a number of optimizations being made that hint there should be a 'better' way. cheers! ----nubis :)