SEATTLE — Elastic, a software start-up in Amsterdam, was rapidly
building its business and had grown to 100 employees. Then Amazon
came along.

In October 2015, Amazon’s cloud computing arm announced it was copying
Elastic’s free software tool, which people use to search and analyze
data, and would sell it as a paid service. Amazon went ahead even
though Elastic’s product, called Elasticsearch, was already available
on Amazon.

Within a year, Amazon was generating more money from what Elastic had
built than the start-up, by making it easy for people to use the tool
with its other offerings. So Elastic added premium features last year and
limited what companies like Amazon could do with them. Amazon duplicated
many of those features anyway and provided them free.

In September, Elastic fired back. It sued Amazon in federal court
in California for violating its trademark because Amazon had called
its product by the exact same name: Elasticsearch. Amazon “misleads
consumers,” the start-up said in its complaint. Amazon denied it had
done anything wrong. The case is pending.

Not since the mid-1990s, when Microsoft dominated the personal computer
industry with Windows, has a technology platform instilled such fear in
competitors as Amazon is now doing with its cloud computing arm. Its feud
with Elastic illustrates how it brandishes power in that technical world.

While cloud computing may appear obscure and geeky, it underlies much
of the internet. It has grown into one of the technology industry’s
largest and most lucrative businesses, offering computing power and
software to companies. And Amazon is its single-biggest provider.

Amazon has used its cloud computing arm — called Amazon Web Services,
or A.W.S. for short — to copy and integrate software that other
tech companies pioneered. It has given an edge to its own services by
making them more convenient to use, burying rival offerings and bundling
discounts to make its products less expensive. The moves drive customers
toward Amazon while those responsible for the software may not see a cent.

Even so, smaller rivals say they have little choice but to work with
Amazon. Given the company’s broad reach with customers, start-ups often
agree to its restrictions on promoting their own products and voluntarily
share client and product information with it. For the privilege of selling
through A.W.S., the start-ups pay a cut of their sales back to Amazon.

Some of the companies have a phrase for what Amazon is doing: strip-mining
software. By lifting other people’s innovations, trying to poach their
engineers and profiting off what they made, Amazon is choking off the
growth of would-be competitors and forcing them to reorient how they do
business, the companies said.

All of this has fueled scrutiny of Amazon and whether it is abusing its
market dominance and engaging in anticompetitive behavior. The company’s
tactics have led several rivals to discuss bringing antitrust complaints
against it. And regulators and lawmakers are examining its clout in
the industry.

“People are afraid that Amazon’s ambitions are endless,” said
Matthew Prince, chief executive of Cloudflare, an A.W.S. competitor that
protects websites from attacks.

A.W.S. is just one prong of Amazon’s push to dominate large swaths of
American industry. The company has transformed retailing, logistics, book
publishing and Hollywood. It is rethinking how people buy prescription
drugs, purchase real estate and build surveillance for their homes
and cities.

But what Amazon is doing through A.W.S. is arguably more
consequential. The company is the unquestioned market leader —
triple the size of its nearest competitor, Microsoft — in the seismic
shift to cloud computing. Millions of people unknowingly interact with
A.W.S. every day when they stream movies on Netflix or store photos on
Apple’s iCloud, services that run off Amazon’s machines.

Jeff Bezos, Amazon’s chief executive, once called A.W.S. an idea
“no one asked for.” The service began in the early 2000s when the
retailer struggled to assemble computer systems to start new projects
and features. Once it built a common computer infrastructure, Amazon
realized other companies needed similar capabilities.

Now companies like Airbnb and General Electric essentially rent computing
from Amazon — otherwise known as using the “cloud” — instead of
buying and running their own systems. Businesses can then store their
information on Amazon machines, pluck data from them and analyze it.

For Amazon itself, A.W.S. has become crucial. The division generated $25
billion in sales last year — roughly the size of Starbucks — and is
Amazon’s most profitable business. Those profits enable the company
to plow money into many other industries.

In a statement, Amazon said the idea that it was strip-mining software
was “silly and off-base.” It said it had contributed significantly to
the software industry and that it acted in the best interest of customers.

Some tech companies said they had found more customers through A.W.S.;
even some companies that have tangled with Amazon have grown. Elastic,
for instance, went public last year and now has 1,600 employees.

But in interviews with more than 40 current and former Amazon employees
and those of rivals, many said the costs of what the company was
doing with A.W.S. were hidden. They said it was hard to measure how
much business they had lost to Amazon, or how the threat of Amazon had
turned off would-be investors. Many spoke on the condition of anonymity
for fear of angering the company.

In February, seven software chief executives met in Silicon Valley
and discussed bringing an antitrust lawsuit against the giant, said
four people with knowledge of the gathering. Their grievances echoed
a complaint by vendors who use Amazon’s shopping site: Once Amazon
becomes a direct competitor, it is no longer a neutral party.

The C.E.O.s did not press forward with a legal action, partly out of
concern that the process would take too long, the people said.

Now regulators are approaching some of Amazon’s software rivals. The
House Judiciary Committee, which is investigating the big tech companies,
asked Amazon in a September letter about A.W.S.’s practices. The Federal
Trade Commission, which is also investigating Amazon, has questioned
A.W.S. competitors, according to officials at two software companies
who were called in but were not authorized to discuss the matter.

What Amazon is doing to software start-ups is unsustainable, said Salil
Deshpande, founder of Uncorrelated, a venture capital firm.

“It has intercepted their monetization, it has forcibly wrestled
control of software from their owners and it has siphoned customers to
its own proprietary services,” he said.  ‘Strip Mining’

When Amazon Web Services began last decade, Amazon was struggling to
turn a consistent profit. A service to provide computing power seemed
like a distraction.

Yet start-ups embraced A.W.S. They saved money because they did not need
to buy their own computing equipment, while spending only on what they
used. Soon more companies flocked to Amazon for computing infrastructure
and, eventually, the software that ran on its machines.

In 2009, Amazon established a template for accelerating A.W.S.’s
growth. That year, it introduced a service for managing a database,
which is critical software to help companies organize information.

The A.W.S. database service, an instant hit with customers, did not run
software that Amazon created. Instead, the company plucked from a freely
shared option known as open source.

Open-source software has few parallels in business. It is akin to a
coffee shop giving away coffee on the hopes that people spend on milk
or sugar or pastries.

But open source is a tried and true model nurtured by the software
industry to get technology to customers quickly. A community of
enthusiasts often springs up around the shareable technology, contributing
improvements and spreading the word about its benefits. Traditionally,
open-source companies later earn money for customer support or from
paid add-ons.

Technologists initially paid little attention to what Amazon had done
with database software. Then in 2015, Amazon repeated the maneuver by
copying Elasticsearch and offering its competing service.

This time, heads turned.

“There was a company that built a business around an open-source
product that people like using and, suddenly, they have a competitor
using their own stuff against them,” said Todd Persen, who started a
non-open-source software company this year so there was “zero chance”
that Amazon could lift his creations. His previous start-up, InfluxDB,
was open source.

Again and again, the open-source software industry became a well that
Amazon turned to. When it copied and integrated that software into A.W.S.,
it didn’t need permission or have to pay the start-ups for their work,
creating a deterrent for people to innovate.

That left little recourse for many of these companies, which could not
suddenly start charging money for what was free software. Some instead
changed the rules around how their wares could be used, restricting Amazon
and others who want to turn what they have created into a paid service.

Amazon has worked around some of their changes.

When Elastic, now based in Silicon Valley, shifted the rules for its
software last year, Amazon said in a blog post that open-source software
companies were “muddying the waters” by limiting access to certain
users.

Shay Banon, Elastic’s chief executive, wrote at the time that Amazon’s
actions were “masked with fake altruism.” Elastic declined to make
Mr. Banon available for an interview.

Last year, MongoDB, a popular technology for organizing data in documents,
also announced that it would require any company that manages its software
as a web service to freely share the underlying technology. The move
was widely viewed as a hedge against A.W.S., which does not openly share
its technology for creating new services.

A.W.S. soon introduced its own technology with the look and feel of
MongoDB’s older software, which did not fall under the new requirements.

That experience was top of mind this year when Dev Ittycheria, MongoDB’s
chief executive, attended the dinner with the heads of six other software
companies. Their conversation, held at the home of a Silicon Valley
venture capitalist, shifted to something drastic: whether to publicly
accuse Amazon of behaving like a monopoly.

At the meal, which included the heads of the software firms Confluent and
Snowflake, some of the C.E.O.s said they faced an uneven playing field,
according to the people with knowledge of the gathering. No complaint
has materialized.

“A.W.S.’s success is built on strip-mining open-source technology,”
said Michael Howard, chief executive of MariaDB, an open-source
company. He estimated that Amazon made five times more revenue from
running MariaDB software than his company generated from all of its
businesses.

Andi Gutmans, an A.W.S. vice president, said some companies wanted to
be “the only ones” to make money off open-source projects. He said
Amazon was “committed to making sure that open-source projects remain
truly open and customers get to choose how they use that open-source
software — whether they choose A.W.S. or not.”

By the time A.W.S. held its first developer conference in 2012, Amazon
was no longer the only big player in cloud computing. Microsoft and
Google had introduced competing platforms.

So Amazon unveiled more software services to make A.W.S. indispensable. In
a speech at the event, Andy Jassy, the head of A.W.S., said it wanted
to “enable every imaginable use case.”

Amazon has since added A.W.S. services at a blistering pace, going from
30 in 2014 to about 175 as of December. It also built in a home-field
advantage: simplicity and convenience.

Customers can add new A.W.S. services with a single click and use the
same system to manage them. The new service is added to the same bill
and requires no extra permission from a finance or compliance department.

In contrast, using a non-Amazon service on A.W.S. is more complicated.

Today when a customer logs onto A.W.S., they see a home page called the
management console. At the center is a list of about 150 services. All
are A.W.S.’s own products.

When someone types “MongoDB,” the search results do not fetch
information for MongoDB’s service on A.W.S.; it instead suggests an
offering from Amazon that is “compatible with MongoDB.”

Even after a customer has selected a non-Amazon option, the company
sometimes continues pushing its own product. When someone creates a new
database, they are presented an ad for Amazon’s own technology called
Aurora. If they pick something else, Amazon still highlights its option
as “recommended.”

Mr. Gutmans said A.W.S. worked closely with many companies to integrate
their offerings “as seamlessly as possible.” Banning Words

Amazon’s A.W.S. developer conference is now one of the world’s
biggest technology events, drawing tens of thousands of people to Las
Vegas every year.

The highlight is a speech from Mr. Jassy where he showcases new
services. Because a new A.W.S. feature often spells hardship for some
start-up, the presentation has earned the nickname “The Red Wedding,”
a bloody event in a “Game of Thrones” episode.

“Nobody knows who is going to get killed next,” said Corey Quinn of
the Duckbill Group, who helps companies manage their A.W.S. bills and
writes a newsletter called “Last Week in A.W.S.”

At last year’s conference, Amazon unveiled a new tool — Amazon
CloudWatch Logs Insights — to help customers analyze information about
its services.

Daniel Vassallo, a former A.W.S. software engineer who helped develop
the product, said executives wanted to go after the market, but were
worried it would look like Amazon was targeting a company called Splunk,
which offers a similar tool and is also a major spender with A.W.S.

So Amazon previewed its new product to Splunk before the conference and
agreed not to announce it during Mr. Jassy’s speech, Mr. Vassallo said.

“They weren’t particularly happy. Who would be?” Mr. Vassallo,
who left Amazon in February, said of Splunk. “But we still went ahead
and did it anyway.”

Splunk said it had a “strong partnership” with A.W.S. and declined
to comment further.

Amazon has also created rules for its developer conference. Companies
that pay tens of thousands or hundreds of thousands of dollars for a
booth said they must submit their banners, pamphlets and news releases
to Amazon for approval.

According to an A.W.S. document from August explaining marketing
guidelines for companies it works with, Amazon bans certain words or
phrases, such as “multi-cloud,” the concept of using two or more
cloud platforms. An Amazon spokesman said it had stopped this practice.

Companies are also instructed to strike claims about being “the best,”
“the first,” “the only,” “the leader,” unless substantiated
by independent research.  ‘Love-Hate Relationship’

Redis Labs was founded in 2011 in Tel Aviv, Israel, to build a business
around managing a free software called Redis, which people use to organize
and update data quickly. Amazon soon offered a competing paid service.

While that created a formidable rival to Redis Labs, Amazon’s move also
validated Redis technology. The start-up has since raised $150 million,
exemplifying the can’t-live-with-can’t-live-without relationship
that many software companies have with Amazon.

Former Redis Labs employees estimate that Amazon generates as much as
$1 billion a year from Redis technology — or at least 10 times more
revenue than Redis Labs. They said Amazon also tried to poach its staff
and undercut it with hefty discounts.

A.W.S. offers a discount to customers who commit to spending at least a
certain amount with it, but it does not treat money spent on A.W.S.’s
own services and rival services equally. Spending on outside services
counts as only 50 cents on the dollar toward the balance. And discounts
do not apply to non-Amazon products, according to A.W.S. customers.

If a customer still chooses Redis Labs through A.W.S., Redis Labs is
required to kick back around 15 percent of its revenue to Amazon.

At one point, Amazon’s attempts to hire Redis Labs employees became
so aggressive that executives removed some online biographies of its
technical staff, said the former employees. A Redis Labs spokesman said
the start-up had no recollection of that.

Some Redis Labs executives considered bringing an antitrust action against
Amazon this year, the former employees said. Others balked because 80
percent of the start-up’s revenue came from customers on A.W.S.

“It was a love-hate relationship,” said Leena Joshi, a former
vice president of marketing at Redis Labs. “On one hand, most of
our customers ran on A.W.S. so it was in our interest to be tightly
integrated with them. At the same time, we knew they were taking away
our business.”

Redis Labs declined to comment on its revenues or A.W.S. actions. It
said Amazon offered “important services.”

Not every company views A.W.S. as a threat. Ali Ghodsi, chief executive of
Databricks, a San Francisco start-up that uses artificial intelligence
to analyze data, said A.W.S. salespeople have lifted sales of his
company’s products.

“I don’t see them using shenanigans to stop us,” he said.

But Saket Saurabh, chief executive of Nexla, a 14-person start-up in
Millbrae, Calif., said he had reservations about Amazon.

In August, Amazon began a service for processing and monitoring data
that competes with Nexla. Investors warned him about sharing too much
information with the giant.

Mr. Saurabh went ahead anyway and signed his company up to work with
Amazon in September. The reason? Amazon’s giant sales teams can give
Nexla access to a vast audience.

“What choice do we have?” he said.