THE first ever e-commerce transaction, conducted by students from Stanford and MIT in the early 1970s, involved the sale of a small quantity of marijuana. For decades afterwards, the online drugs trade was severely constrained by the ability of law enforcement to track IP addresses and the means of payment. The trickle of transactions threatened to become a flood with the emergence a few years ago of Silk Road, a drug-dealing site on the “dark net”. These e-depths cannot be reached through a normal browser but only with anonymising software called Tor. Buyers and sellers transact there pseudonymously in bitcoin, a crypto-currency.

Silk Road was shut last year with the arrest of Ross Ulbricht, the 29-year-old American whom investigators believe to be Dread Pirate Roberts, the site’s founder. Mr Ulbricht is due to stand trial in New York next January on charges that include computer hacking and money laundering. But law enforcers who predicted that Silk Road’s demise would mark the beginning of the end for online black-market bazaars were wrong. Instead, dozens of dark-net Amazons and eBays (also known as crypto-markets) have sprung up to fill the void. They are not only proving remarkably resilient but expanding their offerings and growing more sophisticated.

The number of for-sale listings in the 18 crypto-markets tracked by the Digital Citizens Alliance (DCA), an advocacy group, grew from 41,000 to 66,000 between January and August. The largest market until August, Silk Road 2.0 (whose logo, like its predecessor’s, features an Arab trader on a camel), has since been overtaken by two upstarts, Agora and Evolution, whose combined listings have grown by 20%, to 36,000 in the past two months. Each of these three has more listings than the original Silk Road ever did (see chart). It is unclear whether listings are a good measure of sales, which the markets do not disclose.

Vendors vary in size: the largest turn over several million dollars a month on a single site, the smallest a few hundred. They pay a fee to register and a commission per transaction, typically 3-6%. Buyers come from all over the world. Their purchases are sent by post—the vast majority appear to arrive undetected. Customer satisfaction is high. Illegal and prescription drugs are the largest product category. (Some sellers are crooked pharmacists.) Silk Road 2.0, whose operators are avowedly libertarian, focuses almost exclusively on weed, powders and pills. Agora, whose mascot is an armed bandit, sells weapons, too. These are marketed mostly to Europeans, who face strict gun-control laws. The fastest-growing of the big three, Evolution, is the least principled. Though, like the others, it bans child pornography, it hawks stolen credit-card, debit-card and medical information, guns and fake IDs and university diplomas. One-fifth of its listings are in its “Fraud” section or in “Guides and Tutorials”, which often explain how to commit crimes. Some see Evolution’s rapid growth as a worrying sign that cyber-criminals are looking to fuse their identity-theft operations with the “victimless” online drugs trade. (It is not, however, the most unsavoury corner of the dark net, where some make markets in contract killings.) For drug buyers, online markets offer several advantages. They are less physically dangerous than street trades. This goes for dealers, too: a recent study found that a third or more of sales on Silk Road were to “a new breed of retail drug dealer”, a transformation of the wholesale market that “should reduce violence, intimidation and territorialism.”

Product quality is higher, largely thanks to an Amazon-like five-star customer-review system. With 29 reviews for the average listing on Silk Road 2.0, a high score provides reassurance. MDMA (or ecstasy) is particularly popular on the site, presumably because the street version can be laced with lethal impurities. The dark net’s hundreds of forums provide further intelligence on dodgy gear and scammers. The FBI made over 100 purchases on Silk Road before closing it down. An agent testified that these showed “high purity levels”.

High ratings are sellers’ lifeblood. Reputation is crucial when clients know they cannot fall back on small-claims courts or arbitration. “It’s the ultimate irony: a den of thieves who don’t know each other but need to trust each other,” says a researcher with the DCA who requested anonymity for reasons of security.

As drug sales move online, power is shifting to buyers. The big markets’ customer service and marketing strategies increasingly resemble those of legitimate retailers. They are quick to apologise for technical glitches. Two-for-one specials, loyalty discounts and promotional campaigns are common (on Smoke Weed Day, say). Other methods borrowed from the corporate world include mission statements, terms and conditions, and money-back guarantees. “It has become so prosaic it could be shoes,” says James Martin, author of “Drugs on the Dark Net”.

Markets are also innovating to cut fraud. In the free-for-all in the months after Silk Road’s closure, thousands of buyers lost bitcoins that were supposedly held in escrow, either because markets were hacked or because their administrators ran off with the money. The emerging solution is “multi-signature” escrow, from where funds can be moved only with the approval of a least two of the three interested parties (buyer, seller and market). Some markets are trying to build a community of trusted buyers and sellers with invitation-only participation. Those whose customers had bitcoins stolen have begun to devise schemes to make them whole.

Sites that specialise in stolen card data display their own brand of customer-friendliness. Some offer a service that allows buyers to verify purchased cards are still active, using compromised merchant accounts. The client’s balance is automatically refunded the value of cards that are declined. (Cards sell for anywhere from $10 to $100 each.) Others batch their cards for sale according to the location of the hacked retailer, says Brian Krebs, a cyber-security blogger. Buyers favour cards stolen from consumers who live nearby because banks often treat transactions as suspicious if they take place far from the legitimate cardholder’s home address. A site that has pioneered this segmentation is McDumpals. Its logo features a gun-toting Ronald McDonald and its motto is “I’m Swipin’ It”.

Several factors make life hard for those looking to crack down on the dark net, including its technical complexity, the physical separation of buyers and sellers, and their mobility (vendors typically post on more than one market, allowing them to keep selling if a site goes offline). Tellingly, the only market forcibly closed since Silk Road was Utopia, which was shut by Dutch authorities soon after it opened in February. Some law enforcers want to target Tor, but even if that were technically possible it would cause “collateral damage”, points out Nicolas Christin of Carnegie Mellon University, because the software has worthy uses, such as to protect whistleblowers.

Moreover, the deep web’s denizens will continue to adapt. Jamie Bartlett, author of “The Dark Net”, predicts: “The future of these markets is not centralised sites like Silk Road 2.0, but sites where…listings, messaging, payment and feedback are all separated, controlled by no central party”—and thus impossible to close.