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Thom Kim and Joseph Turian, winners of the $1 Million from Salesforce.com.

Salesforce.com says it's still looking into claims that the developers who won its massive $1 million hackathon contest had broken the rules and shouldn't have won.

But it is, so far, standing by the choice, saying that the app submitted was deemed "eligible" to win at the time it was submitted, wrote Adam Seligman, who leads Salesforce.com's developer relations, in a blog post.

At the same time, Salesforce.com left itself an out to change its mind. Seligman said that "we are conducting a thorough review of the final entries to ensure they complied with published rules and regulations."

The grand prize of $1 million was the biggest ever for a hackathon, which is an event where developers gather together and work nonstop to build something new.

A team of two developers won the prize, Thom Kim and Joseph Turian, for a voice-activated app called Upshot. Kim had previously worked at Salesforce as an engineer for nine years. He had left Salesforce in January.

Developers who participated aired a long list of complaints about the contest. Sources told Business Insider that a lot of them were "furious" about the way it was conducted.

The biggest complaint was that the app that won wasn't created as part of the Hackathon. People voicing complaints found evidence that Upshot team member Kim had publicly demonstrated the app to Salesforce.com users at a Meetup event on Oct. 8, weeks before the Hackathon contest was even announced on Oct. 25.

But that wouldn't necessarily disqualify the app, Seligman said in the a blog post.

That's because Salesforce.com told developers during the contest that it was OK for them to use older code in their hackathon app. The judges were supposed to ignore that older code and only look at the new features built after the contest was announced.

Another accusation was that judges didn't even look at all the apps submitted before handing the prize to a former employee. These complaints were aired on a Salesforce.com discussion forum and in a thread on Hacker News.

Alicia Liu, part of team " SalesRun" also wrote a long blog post about her experience at the hackathon, called "The Dirty Secret Behind the Salesforce $1M Hackathon." After her team submitted their app:

"I saw a bland standard rejection email ... specifically stating no judging feedback will be given. ... the Testflight email with our [app] wasn’t even opened. ... Having spent collectively over 150 hours working on something, giving up nights and weekends, and not even have someone actually look at our app left a distinctively sour taste."