Is PDF Editor for Chrome:Edit, Fill, Sign, Print safe?

// If the PDF is a local file (file:// URL), read it and base64-encode it
async function getLocalDocumentByUrl(request) {
    const { url } = request;
    const isLocalDoc = url.indexOf('file://') > -1;
    if (!isLocalDoc) return; // remote URLs skip this step

    const response = await fetch(url);          // reads the file from disk
    const buffer = await response.arrayBuffer();
    // encode the raw bytes as base64 and attach to the request object
    request.file = btoa(
        new Uint8Array(buffer).reduce(
            (data, byte) => data + String.fromCharCode(byte), ''
        )
    );
    // request.file is now the entire PDF encoded as base64
}

// Sends the PDF to pdffiller.com and returns the editor URL
function sendPdffillerAPI(request, sender, sendResponse) {
    const options = {
        source: 1,
        filename: request.filename,
        pdf_url: request.url,      // remote PDF: send the URL
        type: 'chrome.ext',
        out: 'json'
    };
    if ('file' in request) {
        // local PDF: drop the URL field, send the full base64 file contents
        delete options.pdf_url;
        options.pdf_file = request.file;
    }
    fetch('https://www.pdffiller.com/flash/data/up.php', {
        method: 'post',
        body: new URLSearchParams(options),
        headers: { 'Content-Type': 'application/x-www-form-urlencoded;charset=UTF-8' },
    })
    .then(res => res.json())
    .then(res => {
        // open the pdffiller editor in a new tab
        sendResponse(res.url + '?' + utmParams);
    });
}

// Fires when the user clicks the pdfFiller button on a Gmail attachment
$(document).on('click', '.pdffiller-link', function() {
    // locate the attachment container element in Gmail's DOM
    var attachment = $(this).parents('.aZo.N5jrZb');
    var file = attachment.attr('download_url').split(':');
    var name = decodeURI(file[1]);   // the attachment filename
    var url  = file[2] + ':' + file[3]; // the download URL
    getFile(url, name, 'GMAIL');     // type='GMAIL' triggers the metadata scrape
});

function getFile(url, filename, type) {
    // ask the service worker to fetch the file bytes
    chrome.runtime.sendMessage({ contentScriptQuery: 'getGmailFile', url }, file => {
        if (type === 'GMAIL') {
            // scrape sender email from Gmail's DOM
            var from    = $('.iv .gD').attr('email');  // sender address attribute
            var subject = $('.nH .ha .hP').html();    // email subject line
            // send file + metadata to service worker for upload
            sendToPdffillerGmailApi(file, filename, from, subject);
        }
    });
}

// Uploads the attachment and email metadata to pdffiller.com
function sendPdffillerGmailAPI(request, sender, sendResponse) {
    $.post('https://www.pdffiller.com/flash/data/up.php', {
        filename: request.filename,
        pdf_file: request.file,    // base64-encoded attachment contents
        type:     'GMAIL',         // identifies this as a Gmail attachment upload
        from:     request.from,    // sender's email address (scraped from DOM)
        subject:  request.subject, // email subject line (scraped from DOM)
        out:      'json'
    }, function(json) {
        if (json.result) {
            // open the pdffiller editor for the uploaded attachment
            sendResponse(json.url);
        }
    }, 'json');
}