Is there a storage limit for attachments in online QuickBooks? How often are company files backed up by Intuit?

Thanks for checking in with us, rahmat-mosaik-ng. 

There is no file size or storage limit for attachments you store locally, however, there must be enough space on your local system to store the documents. Also, to protect the security of your QuickBooks Online account, the file types you can attach are limited to the following:

• PDF
• JPEG
• PNG
• DOC
• XLSX
• CSV
• TIFF
• GIF
• XML

Here's an article you can refer to for more details about Attachments in QuickBooks Online. Also, each field in your company data file has a maximum number of characters that can be entered. You can check out this article for the maximum number of characters you can enter in each field: Character limitations for fields in QuickBooks. 

On the other hand, automatic backups are performed every night. The security of your data is our priority and that's why we’ve invested a great deal of thought and resources into ensuring a completely reliable system. To learn more about this one, check out this article: Do I need to back up my data with QuickBooks Online?.

For more tips and other resources, you may visit our page in managing your business in QuickBooks: QuickBooks Self-help articles.

Do you need more help completing other tasks in QuickBooks? Please let me know and I'll assist you with some guides and other pointers. Have a great weekend.

@rahmat-mosaik-ng 

You can utilize a backup restore app to integrate with your QBO.

https://rewindio.grsm.io/quickbooks