With all the talk about the algorithms that make big data sing, we usually overlook all the maintenance and cleaning up of the data that has to be done before even thinking about firing up the report engines. CrowdFlower is using crowdsourcing to simplify this process, and the company announced today that it has put together $12.5 million in funding to help it grow.

Big data sounds great on the surface — a company might have a massive database of sales numbers and demographics. But invariably some data may be placed in the wrong fields, some fields may be left empty, and information might be incomplete or incorrect. You can’t really teach a machine to fix these types of things. You need human beings.

That’s where CrowdFlower comes in. It has a network of 5 million people whom it pays to help clean and organize data. The company posts the jobs on its website, and its contributors grab the ones they want to do.

“We have more than 5 million contributors,” CrowdFlower spokeswoman Kelly Mayes tells VentureBeat. “Some of them are stay-at-home moms. Many of them have graduate degrees.”

Projects can include tasks like search relevance tuning, data categorization, image annotation, content moderation, sentiment analysis, metadata creation, and real-time transcription.

The company lists eBay, Edelman, EventBrite, The Home Depot, VMWare, and Venuelabs as customers.

The funding round is led by Canvas Venture Fund with participation from existing investors Bessemer Venture Partners and Trinity Ventures. The investment brings the total amount raised by the company to $28 million and will be used to help the company grow its product and customer base.

“We founded CrowdFlower five years ago to address the painful and time-consuming challenges data scientists face on a daily basis,” said CEO Lukas Biewald in a statement Wednesday.