Signing up to a group on SMS is not like registering on a Web form, so GupShup doesn't collect any data.

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"Google claims it does not collect personal data but doesn't say who decides what information is 'personal', " she said.

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The site doesn't collect a lot of demographic data on its users, but Mr. Gottfrid said there is an opportunity to target ads based on the content a user is interested in.

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