Salesforce has come under scrutiny after some controversy surrounding the winners of its recent hackathon competition.

The CRM and cloud computing company is investigating the finalists in its $1m mobile apps hackathon to ensure they did not break the competition rules.

App design company Upshot beat four other finalists at the hackathon. Co-founders Thomas Kim and Joseph Turian were presented with the cash prize by Salesforce CEO at the annual Dreamforce conference in California.

Salesforce VP of developer and partner marketing, Adam Seligman acknowledged the discrepancy when he published a blog entitled: ‘Addressing questions about the Salesforce $1 million hackathon.’

"Every eligible app entry was reviewed at least twice. In addition, all of the final five teams met the eligibility requirements specified in the Official Rules," he said.

But it has emerged that Kim is a former Salesforce employee, who served as a lead analytics engineer for nine years. The hackathon rules forbid any Salesforce employ after 1 September 2013 from taking part.

It has not been confirmed when Kim left Salesforce, but him long term employment with the company has been a cause of upset for many.

There are also accusations that Kim developed the app at least one month before the November hackathon after he reportedly was demonstrating the software at Upshot during a meet up on 8 October. This is also against the competition rules as they clearly state the apps must have been ‘developed solely as part’ of the hackathon:

"Reusing code you may have written before is fine, provided that you were the author of that code, it doesn’t comprise the majority of your app and its use does not violate any third party’s rights. You could modify an existing product to integrate with Salesforce and submit that, however you’d be judged on just that component, not the pre-existing product."

Salesforce CEO Marc Benioff is now promising a thorough investigation of the hackathon.