Felix Weis (left) in Prague, with one of his few purchases in euros.

Felix Weis has become used to blank stares any time he tries to pay for something. Since January, the 28-year-old freelance computer programmer from Luxembourg has been on a trip around the world using only bitcoin.

Most store clerks, bartenders and tour operators he's encountered have never heard of the virtual currency. But that is what Weis intended. He is targeting ordinary people rather than tech geeks who already understand it.

"Bitcoin is the most exciting global socioeconomic experiment right now," Weis said. "I really believe in it."

As proof of his devotion to the six-year-old currency, Weis converted all his money into bitcoin and cut up his credit card. He carries the two halves in a clear plastic bag for anyone who doubts his seriousness.

Often three or four people gather to listen as he — usually — convinces someone to accept it as payment. Then he pulls out a selfie stick.

In the 14 countries Weis has visited so far, he has snapped dozens of photos with first-time bitcoin users holding up their smartphones to show off their first transaction. That includes this reporter.

Bitcoin was invented as an alternative to government-run monetary systems, and allows users to make payments instantly and anonymously, even across borders, with no need for a bank or other third party. It can be used to buy goods and services, traded for traditional currency on a bitcoin exchange, or stored in a virtual "wallet".

The virtual currency is controlled by an international network of computers, rather than a central bank or government. Its underlying technology is the blockchain, a sort of public ledger of each bitcoin transaction. Thousands of specialised computers worldwide verify transactions using a computer code that — in theory — is unbreakable.

That transparency and cryptographic proof are bitcoin's appeal for users who distrust banks or government-backed currencies — or would like to keep their transactions out of sight.

To use bitcoin, you need to first download a bitcoin wallet app to your smartphone. Then you can buy bitcoins online through an exchange, or in person through a local seller. Websites such as spendbitcoins.com show where you can spend bitcoin in your area.

Its potential advantages for frequent travellers are obvious: paying by bitcoin is instantaneous, with no need to exchange currency in each country or pay foreign transaction fees.

Weis intends to visit 21 countries by the end of the year to symbolise the 21 million bitcoins that can ever come into use, as designed by the currency's mysterious founder, who is known only by the name Satoshi Nakamoto. The name is widely believed to be fake.

Weis sticks to three rules. He must use bitcoin whenever possible to pay for food, accommodations and travel. He can never use a debit or credit card.

And he may use limited amounts of local currency, but only if he obtains it by exchanging bitcoin for physical money with local people found via a special website, localbitcoins.com.

Varying success

So far he has visited much of Europe, plus Turkey, Israel and Ukraine. To book his travel, Weis uses travel companies that accept the digital currency. Expedia.com customers can use it to pay for hotel bookings, while CheapAir takes it for hotels and flights.

After a free historical tour of the Israeli port city Jaffa, Weis had offered to tip his tour guide in bitcoin. To do so, he had her download a bitcoin wallet app to her smartphone, then used his own phone to scan the wallet's QR code. Within seconds the guide possessed the bitcoin equivalent of 30 shekels.

Finally, Weis pulled up a map of Tel Aviv on Coinmap.org to show her all the nearby stores, restaurants and services where she could spend it.

In other countries, Weis has used the virtual currency to pay for scuba diving lessons, paragliding and bungee jumping. Weis' experiences in each country vary widely depending on bitcoin adoption rates and awareness. Sometimes he has a limited choice of stores, restaurants and activities, and he can't always persuade merchants to take a chance on a new currency.

For a few days in Varna, Bulgaria, Weis' only meal was the complimentary hotel breakfast. Budapest and Berlin had the most places that took bitcoin. In Turkey in May, Weis celebrated "Bitcoin Pizza Day" — the anniversary of the first real-world transaction using bitcoin in 2010 — two days late because it took him that long to find a pizzeria he could convince to accept it.

Despite his enthusiasm for bitcoin, Weis does not encourage others to go to the same extremes. As with any digital technology, bitcoin wallets are susceptible to hacking or file corruption. But unlike bank-issued cards, bitcoins aren't overseen by an authority that can help in those situations.

The currency is highly volatile: At one point in 2013, the price per bitcoin soared to more than US$1200 ($1819) and crashed 70 per cent a month later. Days after he started his trip, Weis thought he would have to cut it short by two months when the price dropped to US$180. He'd budgeted for a year with bitcoin selling for at least US$250. It now trades around US$255 on the Bitstamp exchange.

Last week, Weis flew to Hong Kong to begin the Asian leg of his journey. He will go to South America later in the fall. He hopes to learn more about how bitcoin is used differently depending on economic factors, he said.

In the Philippines, for instance, personal remittances make up 10 per cent of the GDP. Bitcoin makes it cheaper to transfer money, because there's little to no fee.

Meanwhile, in Venezuela and Argentina, bitcoin adoption has been fueled by high inflation and capital controls. At least 65 per cent of Latin Americans do not have bank accounts, but many do have smartphones, which give them easy and cheap access to bitcoin, according to Sebastian Serrano, founder of BitPagos, Argentina's biggest bitcoin company.

Weis' last stop will be Berlin, where his trip began and where he's thinking about creating a software startup to make using bitcoin "easier and safer for the average person." He says he would like to get paid in bitcoin and plans to keep his savings in the digital currency as well.

Said Weis: "Now that I know it's possible to live off bitcoin in 14 countries, why go back to the boring old system?"