Microsoft has released a free tool that lets websites spot when images of child abuse are being shared by users.
It said it had made the PhotoDNA tool available to tackle the 720,000 abuse images uploaded to the net every day.
Police forces, anti-abuse organisations and large social networks have been using the tool for some time to dig out the illegal images.
Microsoft said the online tool was for smaller web firms without the resources to do image-checking themselves.
Spotting abuse images among the 1.8 billion pictures uploaded to online services every day was an almost impossible task, said Courtney Gregoire, a senior lawyer at Microsoft’s Digital Crimes Unit in a blogpost outlining the initiative.
While many large social networks such as Twitter, Facebook and Flipboard were already using PhotoDNA, before now it had not been available to smaller online services, she said.
“We needed an easier, more scalable way to identify and detect these worst-of-the-worst images,” said Ms Gregoire.