Borrow library books, buy train tickets, pick up online orders or even eat dinner with friends -- Taiwan's expansive network of convenience stores takes the concept to a whole new level.

The island of 23 million people is home to the highest density of convenience stores in the world, with more than 10,000 in total -- one per 2,300 people.

But as the number of physical shops plateaus, the retail chains are turning to alternative ways to keep money rolling in.

As well as selling standard snacks and toiletries, Taiwan's plethora of 7-Elevens and FamilyMarts then moved to serve up hot meals, from steamed buns to soups and stews, day and night.

Now they are revamping their dining areas and adding fancier meals to the menu -- Japanese ramen, Korean kimchi stew, pesto pasta -- complete with calorie labels.

FamilyMart, a Japanese chain, has even introduced crossover stores with Taiwanese organic produce vendor Tanhou, selling frozen fish and naturally yeasted breads.

But it is by tapping into the island's thriving online retail culture that the ubiquitous stores hope to become the ultimate one-stop shop.

Taiwan's e-commerce market is worth Tw$1.1 trillion ($35 billion) and is set to grow another 11 percent this year.

However, cash is still most online customers' preferred form of payment and many choose to have their internet orders delivered to convenience stores where they then pay for them.

Morning Shop, a popular new online vendor of imported breakfast cereals and granola bars says 85 percent of its sales are settled at convenience stores rather than paid for online.

"Doubts over the safety of online payments are still quite high and seen as more troublesome," said the firm's product manager Chris Chen.

The firm has seen its monthly sales surge from Tw$620,000 ($19,739) in 2015 to an expected Tw$30 million within the first quarter this year.

Convenience stores are also reaping benefits from the arrangement.

They make a slim profit from each transaction and are hoping volume will turn it into a moneyspinner.

FamilyMart aims to up e-commerce to 10 percent of its revenue in five years.

President Chain Store Corp (PCSC) which owns the Taiwan franchise of US chain 7-Eleven, says cash payments for online purchases "abolish the non-trust issue".

"Taiwan can do this while other countries can't because we're a relatively small island," it said in a statement to AFP.

- Plugged in -

Convenience stores are also finding a place in the logistics of daily life.

The shop chains double as a delivery network, enabling residents to send belongings from one part of the island to the other.

Student Lee Yun-hsuan uses them as a postal service when she needs to haul books to and from university.

Lee, 20, sends a box of books from a convenience store near her university on Taiwan's east coast to the closest outlet near her home in Taipei.

"Post offices aren't everywhere and they're not always open," she told AFP.

They have even linked up with libraries in Taipei so readers can pick up borrowed books at a convenience store of their choice.

Now they want to take things to the next level so shoppers can access their services on smartphones.

7-Eleven has introduced the 'iBon' system, with machines installed in most of its shops performing a myriad of functions, including photo printing, purchasing train and concert tickets, or paying parking fines.

Taiwanese franchise owner PCSC is working on expanding iBon's reach by turning it into a mobile application.

"We want to get to the point where everyone can have an iBon in their pocket," it said.

As they ratchet up their tech credentials, residents are increasingly using convenience stores as a catch-all.

Taipei resident Serena Chen, 40, says she goes to a local store at least twice a week, paying her bills over the counter and using photocopying and scanning services.

She also has books and magazines ordered online delivered to the stores for pick-up and payment.

But Chen says the shops' more basic offerings -- from sugary treats to potato chips -- still play their part.

"When I was stressed out at my last job I went every day," Chen told AFP.

"I needed snacks!"