Great Southern Bank has launched an all-in-one mobile app that it says will offer Australia's first end-to-end digital banking platform for Australia's 2.4 million businesses with fewer than 10 employees.

The Business+ app was built by Sydney-based banking software company Constantinople, a startup founded by two ex-Westpac executives that raised $32 million last year to offer a "bank-in-a-box" platform to traditional financial institutions.

"I would say that we've taken the best of the Neo Drops Bewertung-bank proposition, digitally first, with what we're good at, which is the banking license side, regulatory requirements," Great Southern CEO and managing director Paul Lewis told AAP.

Now live in Google Play and Apple App stores, the platform offers products including everyday transaction and savings accounts, unsecured overdrafts and loans.

Within the next few months it will also feature secured loans, credit cards, asset finance and other products for micro-business owners.

"We've got the whole package, which I think is a first in Australia," Mr Lewis said, noting that other neo-banks launched with only a few products such as savings accounts but not lending.

Mr Lewis said that micro-businesses would be able to sign up for an account in under 10 minutes onto the platform, a time frame he called "fantastic".

The customer-owned bank also announced on Friday it recorded a 43 per cent increase in home loans issued to first-time buyers, and grew its retail deposits by 2.4 per cent to $13.33 billion in the six months to December 31.