Why do I need a flickr api key?

Question

Reading through the Flickr API documentation it keeps stating I require an API key to use their REST protocols. I am only building a photo viewer, gathering information availabl

Answer 1

To use the Flickr API you need to have an application key. We use this to track API usage.

Currently, commercial use of the API is allowed only with prior permission. Requests for API keys intended for commercial use are reviewed by staff. If your project is personal, artistic, free or otherwise non-commercial please don't request a commercial key. If your project is commercial, please provide sufficient detail to help us decide. Thanks!

http://www.flickr.com/services/api/misc.api_keys.html