"We worked hard to find the financial resources that would allow us to continue to grow, but ultimately could not raise the funding required to continue operations," the letter explained.

In 2014, Shuddle received a cease and desist letter from California regulators for failing to register with TrustLine, a company that runs background check for adults working closely with children. Reports surfaced last year that the company had yet to take action, despite CEO Nick Allen's assurances that its own background checks "exceed current requirements."

"We sincerely appreciate your loyalty and support as passengers and drivers, and wish we could have continued to work with you longer," Shuddle posted on its website. "We sincerely hope that other family rideshare services can continue successfully on the path that Shuddle helped forge so that families, schools and community organizations continue to receive this much-needs support."