Is there a size limit on files uploaded to Dropbox, Google Drive, etc?

Yes, the file size limits are below:

• Dropbox – 350 GB;
• Google Drive – 5 TB;
• Amazon S3 – 5 TB;
• Microsoft OneDrive – 10 GB;
• OpenStack Swift – 5 GB;
• WebDAV servers – depends on the server settings (usually 50 MB);
• FTP and SFTP servers – depends on the server settings;
• Box – depends on the type of account:
• 250 MB – Free Personal account;
• 2GB – Starter;
• 5GB – Business/Enterprise account.