SimplyGiving.com is not vulnerable to the heartbleed attack, phew!
As you can imagine, we take our security very seriously, and make sure we deliver a fun, easy and secure giving environment for our community.
SSL and data encryption is all very techy, but just try and imagine a big hairy security guard on the top left of your screen making sure nobody malicious gets in... then multiply him by, like, 100 and you're close to the level of security we have in place.
On a serious note, we have conducted on independent SSL lab test on our website via SSSLabs.com and passed with flying colours. Our servers are not vulnerable to the heartbleed attack so rest assured you will not be affected.
If you have any specific concerns please submit a support ticket and we'll be happy to talk more. You can also learn more about the Heartbleed Bug at www.heartbleed.com.