I came across this website yesterday:

www.easyfundraising.org.uk

You register here, search for a suitable charity, simply by inputting "dogs", "cats", etc. You then access your chosen retailer, which includes all the big online retailers including Amazon, via the site.

Taking Amazon as an example and my chosen charity of Dogs Trust, everytime I make a purchase from Amazon (which I do frequently) Dogs Trust will receive 2.5%.

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Yeah it seems like a good idea. I actually donate to Dogs Trust every time I buy/sell on eBay.

I joined anyway, and have decided to support Hope Rescue, which is another Dog Charity who take dogs on death row and try to re-home/foster.