Stripe, which provides a way for individuals and businesses to accept payments over the internet, made the announcement on Twitter on behalf of itself and Facebook.

The Linux Foundation's Core Infrastructure Initiative made a one-time donation of $US60,000. Other donations by individuals have also come in.

The donations came shortly after the American website ProPublica carried a story on Werner Koch, the German developer who is the lone man behind GnuPG, pointing out that he had been running on something like $US25,000 annually since 2001.

Koch was inspired to write GnuPG after hearing a talk by the GNU Project founder Richard M. Stallman in 1997. Stallman started the project in 1984 in order to develop a free operating system; most of the bits and pieces were ready when the Linux kernel was released on the internet and the two were combined into what came to be known as GNU/Linux distributions.

Since he began writing GnuPG, Koch has been on his own for the most part and was about to give it up and take a day job when Edward Snowden's disclosures about blanket surveillance by the NSA were published. He then realised that he had to keep going.