Juzer Burhani

complete flexibility and freedom to move your data in and out of Zoho Invoice at your will.  This is how it is done.
"Yes, we are happy to announce the support for import and export functionality in Zoho Invoice, a feature long awaited but well worth the wait.
What can you import or export?
Your complete set of data!
Yes, you can import or export your customer information, contacts, the items you sell (products or services), invoices and quotes.
What are the formats supported?
We have support for most of the standard formats.

• Data can be exported in CSV (Comma Separated Values), TSV (Tab Separated Values), XLS (Spreadsheet) and JSON formats.  Additionally we also support exporting of customer and contact information in vCards (.vcf files) format.
• You can import your data in CSV (Comma Separated Values) or TSV (Tab Separated Values) formats.  Additionally we also support vCard format for importing your contacts or customer information

If you feel, we have missed out any important format drop us a note.  We will be more than happy to add support for that format.
Couple of screenshots for a quick look:
Importing contact information into Zoho Invoice:
Exporting invoices from Zoho Invoice:
Please feel free to share your comments. "