FreshRSS/app/views/helpers/export/articles.phtml

<?php
    $username = Minz_Session::param('currentUser', '_');

    $articles = array(
        'id' => 'user/' . str_replace('/', '', $username) . '/state/org.freshrss/' . $this->type,
        'title' => $this->list_title,
        'author' => $username,
        'items' => array()
    );

    foreach ($this->entries as $entry) {
        if (!isset($this->feed)) {
            $feed = FreshRSS_CategoryDAO::findFeed($this->categories, $entry->feed ());
        } else {
            $feed = $this->feed;
        }

        $articles['items'][] = array(
            'id' => $entry->guid(),
            'categories' => array_values($entry->tags()),
            'title' => $entry->title(),
            'author' => $entry->author(),
            'published' => $entry->date(true),
            'updated' => $entry->date(true),
            'alternate' => array(array(
                'href' => $entry->link(),
                'type' => 'text/html'
            )),
            'content' => array(
                'content' => $entry->content()
            ),
            'origin' => array(
                'streamId' => $feed->id(),
                'title' => $feed->name(),
                'htmlUrl' => $feed->website(),
                'feedUrl' => $feed->url()
            )
        );
    }

    $options = 0;
    if (version_compare(PHP_VERSION, '5.4.0') >= 0) {
        $options = JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE;
    }

    echo json_encode($articles, $options);
?>