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Functional HTTP client for Elixir with support for HTTP/1 and HTTP/2
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Mint 🌱

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Functional HTTP client for Elixir with support for HTTP/1 and HTTP/2.


To install Mint, add it to your mix.exs file. Unless you're using your own SSL certificate store, also add the CAStore library to your dependencies.

defp deps do
    {:castore, "~> 0.1.0"},
    {:mint, "~> 0.1.0"}

Then, run $ mix deps.get.


Mint is different from most Erlang and Elixir HTTP clients because it provides a process-less architecture. Instead, Mint is based on a functional and immutable data structure that represents an HTTP connection. This data structure wraps a TCP or SSL socket. This allows for more fine-tailored architectures where the developer is responsible for wrapping the connection struct, such as having one process handle multiple connections or having different kinds of processes handle connections.

Below is an example of a basic interaction with Mint. First, we start a connection through Mint.HTTP.connect/3:

iex> {:ok, conn} = Mint.HTTP.connect(:http, "", 80)

This transparently chooses between HTTP/1 and HTTP/2. Requests are sent with:

iex> {:ok, conn, request_ref} = Mint.HTTP.request(conn, "GET", "/", [], "")

The connection socket runs in active mode, which means that the user of the library needs to handle TCP messages and SSL messages:

iex> flush()
{:tcp, #Port<0.8>,
 "HTTP/1.1 200 OK\r\n" <> _}

To handle such messages, Mint provides a stream/2 function that turns messages into HTTP responses. Responses are streamed back to the user in parts through response parts :status, :headers, :data, and finally :done.

iex> {:ok, conn} = Mint.HTTP.connect(:http, "", 80)
iex> {:ok, conn, request_ref} = Mint.HTTP.request(conn, "GET", "/", [], "")
iex> receive do
...>   message ->
...>     {:ok, conn, responses} =, message)
...>     IO.inspect responses
...> end
  {:status, #Reference<...>, 200},
  {:headers, #Reference<...>, [{"connection", "keep-alive"}, ...},
  {:data, #Reference<...>, "<!DOCTYPE html>..."},
  {:done, #Reference<...>}

The connection API is stateless, this means that you need to make sure to always save the returned conn:

# Wrong
{:ok, _conn, ref} = Mint.HTTP.request(conn, "GET", "/foo", [], "")
{:ok, conn, ref} = Mint.HTTP.request(conn, "GET", "/bar", [], "")

# Correct
{:ok, conn, ref} = Mint.HTTP.request(conn, "GET", "/foo", [], "")
{:ok, conn, ref} = Mint.HTTP.request(conn, "GET", "/bar", [], "")

For more information, see the documentation.

SSL certificates

When using SSL, you can pass in your own CA certificate store or use one provided by Mint. Mint doesn't ship with the certificate store itself, but it has an optional dependency on CAStore, which provides an up-to-date certificate store. If you don't want to use your own certificate store, just add :castore to your dependencies.

def deps do
    {:castore, "~> 0.1.0"},
    {:mint, "~> 0.1.0"}


If you wish to contribute check out the issue list and let us know what you want to work on so we can discuss it and reduce duplicate work.

Tests are organized with tags. Integration tests that hit real websites over the internet are tagged with :integration. Proxy tests are tagged with :proxy and require that you run docker-compose up from the Mint root directory in order to run (they are excluded by default when you run $ mix test). A few examples of running tests:

  • $ mix test to run the test suite without caring about Docker and docker-compose up.

  • $ mix test --exclude integration to only run local tests (for example, you don't have an internet connection available).

  • $ mix test --include proxy to run all tests, including proxy tests.


Copyright 2018 Eric Meadows-Jönsson and Andrea Leopardi

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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