Kalkio (https://kalkio.app) uses these open-source libraries and fonts. They run unmodified in your browser.

heic-to 1.5.2 (HEIC/HEIF photo decoding, includes libheif and libde265 compiled to WebAssembly)
  License: GNU Lesser General Public License v3.0 or later (LGPL-3.0)
  Source: https://github.com/hoppergee/heic-to  ·  npm: https://www.npmjs.com/package/heic-to
  It is loaded as a separate, unmodified file, so it can be replaced with any compatible version.
  License text: https://www.gnu.org/licenses/lgpl-3.0.txt

PDF.js (pdfjs-dist 6.3.289), Mozilla Foundation, Apache License 2.0, https://github.com/mozilla/pdf.js
pdf-lib 1.17.1, Andrew Dillon, MIT License, https://github.com/Hopding/pdf-lib
@pdf-lib/fontkit 1.1.1, MIT License, https://github.com/Hopding/fontkit
fflate 0.8.3, Arjun Barrett, MIT License, https://github.com/101arrowz/fflate
qrcode-generator 1.4.4, Kazuhiko Arase, MIT License, https://github.com/kazuhikoarase/qrcode-generator

Fonts: Barlow and Barlow Semi Condensed (Jeremy Tribby) and IBM Plex Mono (IBM),
  SIL Open Font License 1.1, https://openfontlicense.org (Barlow's license is also in /fonts/OFL.txt)