What HTML file do I edit to add code before the before the bottom tag?

use theme’s footer.php

use theme’s footer.php

put the script before </body>

<script type="text/javascript" src="https://cache0.bigcartel.com/shopindie/badge.js"></script>
</body>

Thank you both. That worked.

is there an echo in here?

@samuel. i am really sorry. i do not mean it