Register new user with curl post request - django

Question

I'm trying to implement registration with my Django REST API.
I know how to login or obtain a token, so that one could do
curl -X POST -d "username=user2&password=qwer" http://localhost:8000/signin > index.html
curl -X POST -d "username=user2&password=qwer" http://localhost:8000/api-token-auth/
But what I need now is to register a new user. I tried it this way:
curl --cookie cookie.txt http://localhost:8000/signup/ -H "Content-Type: application/json" -H "X-CSRFToken: TP5mW4dxjpVO6UOk3nG6Ugk8jqv2u8E2" -X POST -d '{"username":"user4","email":"ggg#gmail.com","password":"qwer"}' >index.html
But nothing happens except I get a sign up page in my index.html file. No new user is created in the database.
This is my HTML template of sign up form. It works perfectly.
What request should I pass to my site in order to register a new user?
{% extends 'base.html' %}
{% block title %}Sign up · Parsifal{% endblock %}
{% block javascript %}
<script>
$(function () {
$('#id_username').focus();
});
</script>
{% endblock %}
{% block content %}
<div class="row">
<div class="col-md-6 col-md-offset-3">
<div class="panel panel-default">
<div class="panel-heading">
<h3 class="panel-title">Sign up for Parsifal</h3>
</div>
<div class="panel-body">
<form action="/signup/" method="post">
{% csrf_token %}
<div class="panel-group{% if form.username.errors %} has-error{% endif %}">
<label class="control-label" for="{{ form.username.id_for_label }}">{{ form.username.label }}</label>
<input type="text" class="form-control" value="{{ form.username.value|default_if_none:'' }}" id="{{ form.username.id_for_label }}" name="{{ form.username.html_name }}" maxlength="{{ form.username.field.max_length }}">
<span class="help-block">(Usernames may contain <strong>alphanumeric</strong>, <strong>_</strong> and <strong>.</strong> characters)</span>
{% for error in form.username.errors %}
<span class="help-block">{{ error }}</span>
{% endfor %}
</div>
<div class="panel-group{% if form.email.errors %} has-error{% endif %}">
<label class="control-label" for="{{ form.email.id_for_label }}">{{ form.email.label }}</label>
<input type="email" class="form-control" value="{{ form.email.value|default_if_none:'' }}" id="{{ form.email.id_for_label }}" name="{{ form.email.html_name }}" maxlength="{{ form.email.field.max_length }}">
{% for error in form.email.errors %}
<span class="help-block">{{ error }}</span>
{% endfor %}
</div>
<div class="panel-group{% if form.password.errors %} has-error{% endif %}">
<label class="control-label" for="{{ form.password.id_for_label }}">{{ form.password.label }}</label>
<input type="password" class="form-control" value="{{ form.password.value|default_if_none:'' }}" id="{{ form.password.id_for_label }}" name="{{ form.password.html_name }}">
{% for error in form.password.errors %}
<span class="help-block">{{ error }}</span>
{% endfor %}
</div>
<div class="panel-group{% if form.confirm_password.errors %} has-error{% endif %}">
<label class="control-label" for="{{ form.confirm_password.id_for_label }}">{{ form.confirm_password.label }}</label>
<input type="password" class="form-control" value="{{ form.confirm_password.value|default_if_none:'' }}" id="{{ form.confirm_password.id_for_label }}" name="{{ form.confirm_password.html_name }}">
{% for error in form.confirm_password.errors %}
<span class="help-block">{{ error }}</span>
{% endfor %}
</div>
<button type="submit" class="btn btn-success">Create an account</button>
</form>
</div>
</div>
</div>
</div>
{% endblock content %}