Like many gig economy workers, Amazon Flex drivers start off their day by opening an app.

The Flex app is where drivers find package delivery jobs in their area. After they log in, drivers will repeatedly tap a big orange refresh button until delivery shifts, referred to as "blocks," appear on the screen.

As soon as blocks pop up, drivers race to claim one of a handful of available shifts. They have seconds to claim a shift by swiping on the block then tapping "accept" on the screen. New shifts appear in the app at seemingly random intervals, and if they don't swipe and tap fast enough, the block disappears. The competition can be cutthroat, with hundreds of drivers competing for a handful of blocks at the same time.

In response, some Flex drivers have begun using bots — combinations of hardware and software meant to mimic the action of tapping on blocks — to increase their odds of winning a coveted shift. Bots also remove some of the frustrations of the Flex app, like having to hit refresh constantly.

Using a bot is technically cheating and against Amazon's policies. But for many drivers, bots are their key to making Flex work worthwhile.

Amazon Flex, launched in 2015, remains a side hustle for some drivers, but for others, it has become one of their primary sources of income. The program uses everyday drivers to deliver packages from their own vehicles and operates in about 50 cities. Drivers earn $18 to $25 an hour depending on the type of block, but as independent contractors, they're responsible for any costs associated with their vehicle, like gas, tolls and maintenance.

By letting a bot do some of the gruntwork, users can get blocks faster than a human would be able to. But they also run the risk of Amazon suspending them from the app, since the Flex terms of service prohibit the use of programs or scripts "for the purpose of surveying, manipulating or data mining." If drivers are blocked from using the app, they can't get Flex jobs.

Despite the risks, bots have become an increasingly common tool for Flex drivers. Many have grown frustrated with the intense and often unpredictable nature of grabbing shifts, or they simply want to make more money, according to several current and former Flex drivers. Some of them spoke on condition of anonymity out of fear of retaliation from Amazon.

"Their business model is basically one that acts like someone tossing a fish into a bucket of lobsters," said Jonathan Lee Provost, a former Flex driver. "We all have to fight for a meal and literally have to manually tap several times per second, nonstop, until we see a block."

Drivers also join Facebook groups for other Flexers in their neighborhood, where people alert group members when shifts are posted, said Chad Polenz, an Amazon Flex driver and YouTuber who posts videos about his experience as a gig economy worker. In his two years as a Flex driver in Florida, Polenz said he has learned that Amazon usually drops new shifts in the app around 10:30 to 11:30 a.m. and 2:30 to 4:30 p.m.

"You start to learn when shifts become available, but there's no guarantee you'll open the app and something will be there," Polenz said. "It's completely unpredictable."

An Amazon spokesperson told CNBC that the company prohibits the use of bots.

"We're committed to creating fair opportunities for our delivery partners to secure delivery blocks," the spokesperson said. "The use of third party tools to accept work creates an unfair advantage, is against our policies, and can result in removal from the Amazon Flex program."

Faster than a human

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Not all bots work the same way.

One program, called Zero Flex, uses a script to analyze network traffic between the Flex app on a user's device and Amazon's servers. When the script detects that a new block is available, it's able to grab the blocks before they're released to other users. Drivers pay as much as $500 for access to a script, making it one of the more costly methods.

One Flex driver told CNBC he has used a variety of bots to help him secure blocks in his hometown of Miami, where he said there are a lot of Flexers and, as a result, higher competition. Once scripts became too expensive, he began using a third-party app called Flex Utility, which costs about $20 to download from the Google Play Store.

Flex Utility uses an Android phone's accessibility features to create a virtual button that's overlaid onto the Flex app. The Flex Utility tool refreshes the Flex app, filters out blocks that don't match the user's search criteria and then places the button over appropriate blocks. Drivers can specify what kinds of blocks they'd like to grab based on the pickup center, time of day and type of block.

The app is "quite a bit faster" than a human because it can filter, select and swipe blocks "within a millisecond, while it would take a human at least several seconds," said the developer behind the Flex Utility app, who spoke on condition of anonymity.

The Flex Utility developer claims his app doesn't violate Amazon's terms of service because the user has to manually click the Flex Utility button in the Flex app. Two Flex drivers who use Flex Utility said they haven't been suspended by Amazon when they've used the tool.

There are also devices called autotappers or block grabbers that automate the physical action of tapping the app.

Users clip two cables onto their phone in the location where the refresh button and blocks appear in the Flex app. Once the device is connected to a power source, the phone's touch screen sensors can recognize its taps.

Drivers can buy the devices online for prices that typically cost $50 to $150. They're even available on Amazon's own website, although the devices violate the Flex terms of service. A quick search for "auto clicker" on the marketplace turns up several listings, including one titled "bot auto swiper." While the listings don't always mention the Flex service in the product description, many of the reviews note that the device "makes it easier to get blocks."

Despite their seemingly high-tech design, block grabbers don't always work, drivers say.

Polenz works several gigs in addition to Flex, including driving for Lyft and delivering orders for Instacart and Doordash. He said Flex is usually a "back up" job for him because he gets so much work from Instacart and Doordash.

During one particularly slow summer a few years ago, there were fewer gig jobs available, so Polenz decided to give a block grabber a try for a video. He bought a block grabber on eBay, but found the device wasn't able to tap on the blocks fast enough before another user beat him to it.

"I scooped one or two with it, but it wasn't scooping anything that I couldn't do myself," he said.

More money, more problems

Thanks to bots, drivers have a greater chance of grabbing blocks that are in high demand.

In addition to Flex deliveries, the app has shifts to deliver Whole Foods, Prime Now and AmazonFresh orders. These blocks are considered more valuable than other jobs because customers can add a tip to their order, unlike package deliveries. Drivers will tell the bot only to grab Whole Foods, Prime Now and AmazonFresh shifts so that they can scoop the blocks before others do.

Drivers also use bots to limit their blocks to warehouses that are nearby, since the Flex app could potentially send them to pick up an order at a warehouse 50 miles away. Longer trips mean lost time and more wear and tear on their vehicle. The faster drivers finish a job, the faster they can move onto the next block.

In response to a rise in bots, Amazon has slowed the refresh rate in the Flex app, drivers believe. Multiple drivers told CNBC they think if they click on blocks too quickly, Amazon is able to detect that they're using a bot and will "soft block" them, preventing them from seeing any new shifts for a certain period of time. (Amazon did not immediately respond to a query on this speculation.)

Developers have found ways to make their bots harder to detect. In many apps, users can specify how often they want the device to click. Autotappers also have settings to slow the rate at which the device taps the screen.

Not all members of the Flex community appreciate drivers who attempt to trick their way to getting more shifts.

As Amazon has cracked down on bots, some drivers say they've been mistakenly flagged as using a bot. Additionally, it's become harder for drivers who don't use bots to get blocks, since they can only refresh the app a certain number of times per minute, Provost said.

Omar Montes, a former Flex driver, said bots have gotten much more sophisticated since he first took notice of them in 2017. Back then, bots were limited to autotappers. Now, many drivers are paying for scripts, which has created a "market in itself where people get rich making apps" for Flex drivers. It no longer feels like an equal playing field, he said.

"As soon as blocks become available, as soon as you get a notification on your phone, all of them are gone," Montes said. "You just can't compete with them."