It's a 17-year-old kid against a $35 billion company.

Los Angeles high school student Caleb Benn has developed an app called Uploader for Instagram, which is exactly what it sounds like. It allows users to upload photos to Instagram directly from their computer instead of solely from their phone, which has long been a frustration.

It took Benn a weekend to build and it has been on the Apple app store for a couple weeks, where it's growing in popularity. He said it's making him $1,000 a day. (The app costs $4.99.)

Instagram isn't a fan.

An engineer for the company sent Benn an email on Friday, saying the app violated the company's terms of service and he needed to fix the app by Monday to get it in line.

It's Tuesday, and Benn hasn't fixed anything, mostly because "fixing it" would render the app useless. He said he responded to the company but hasn't heard back.

Instagram declined to comment for this article.

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"I believe it's entirely legal for my app to perform these actions," Benn said.

Technology attorney Mark Grossman, of law firm Tannenbaum Helpern Syracuse & Hirschtritt, disagrees. (He is not affliated with Benn or Instagram.)

"He's wrong," Grossman said.

Instagram, owned by Facebook (FB), has restrictions against using its private API, which Benn's app uses.

Benn admitted he got access to the API by hacking Instagram. "But not to cause damage or anything," he said.

Chris Messina, a Silicon Valley technologist (and, incidentally, the inventor of Twitter's hashtag), posted about Benn's app on Product Hunt, a platform where users review and discuss new technology. Many commenters predicted Benn's app will be shut down.

Messina told CNNMoney the problem is that accessing the API "opens up possibilities for all kinds of abuse, from spambots or people uploading stuff from other channels."

Plus, Messina said, if Instagram wanted users to post from a computer, it would make that possible.

"Instagram, from a product perspective, is intended to be about capturing the moment using your phone's camera," he said. Start enabling computers to upload content, and it could take away the platform's aesthetic and tone.

"That erodes the user experience," he said.

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We downloaded Benn's app at CNNMoney, and while it does work as promised, it's not terribly user friendly. Applying filters is not nearly as easy as using the iPhone app (and the window that pops up is tiny). Benn said he's received similar feedback, and is working to improve it.

If Instagram does want people to stop downloading his app, it could feasibly ask the Apple app store to stop carrying it. But Benn said that won't affect existing users. (Apple did not immediately return request for comment.)

Grossman said he'd counsel Instagram to block Benn and his technology quietly, since it doesn't look great for a big company to chase a 17-year-old with scary legal letters. Best-case scenerio, Grossman said, is that Benn shuts down the app on his own.

"I'm just giving you the grown-up lawyer answer instead of what's cool and what will fly on Twitter," he said.

Benn said he's not ready to take down the app yet. "I'm just going to wait and see," he said.

In the meantime, the money he's making from the app is going to his college fund. He's planning to study computer science.