Photobucket, the pioneering online photo sharing service, has angered users by requiring a $399.99 subscription to link to photos, a change labeled by critics as a ransom demand for the previously-free ability to use images online.

The Denver-based company’s service had previously allowed linking to photos with its free photo storage. Billions of images stored on Photobucket appeared on blogs and other websites.

Photobucket announced on its blog last week that its terms of service changed June 20, but didn't explain further. The change rendered links to Photobucket-stored photos inactive unless the user purchased a $400 per-year level of the service that allows linking and provides 500 gigabytes of storage.

Many users expressed outrage and complained they wanted to leave Photobucket for another service but were unable download their images.

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