When you are searching for a new tool, uploader etc. you always face limits, banners and so on.
Then, a personal list of accepted links:
- https://docupub.com/pdfconvert/
- https://freepdfonline.com/converttopdfa/ – no confidential files
- https://pdf.online/it/pdf-to-pdfa – just one per day
- https://www.ilovepdf.com/it/pdf-in-pdfa – just one per day
- https://www.freepdfconvert.com/pdf-to-pdfa – one per hour