Downloading Large Files with Finch in Elixir

In this TIL, we will explore how to download large files using the Finch HTTP client library in Elixir. Finch is a highly efficient, concurrent HTTP client that utilizes the powerful concurrency features provided by Elixir.

The following code demonstrates how to download a large zip file using Finch:

path = "/tmp/" file =!(path, [:write, :exclusive]) url = "" request =, url), App.Finch, nil, fn {:status, status}, _ -> IO.inspect("Download assets status: #{status}") {:headers, headers}, _ -> IO.inspect("Download assets headers: #{inspect(headers)}") {:data, data}, _ -> IO.binwrite(file, data) end) File.close(file)

This code snippet downloads a large zip file, storing it in the /tmp directory. We first build the Finch request using, and then stream the response by calling By streaming the response, we can efficiently handle large files without consuming excessive memory. The data chunks are written directly to the file using IO.binwrite/2 as they are received, making it an ideal approach for downloading large files.

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