Tech titans like Mark Zuckerberg and Bill Gates have pledged to give away billions through the 'Giving Pledge' - here's where the money is going

Facebook CEO Mark Zuckerberg announced in 2015 that he intends to give away 99% of his Facebook shares — then valued at $45 billion — during his lifetime.

Zuckerberg and his wife, Priscilla Chan, were some of the first people to sign the Giving Pledge in 2010, and they have focused their philanthropic efforts on education and medical research.

Before the 2015 announcement, they had already donated more than $1.6 billion toward philanthropic causes, including $25 million to the CDC Foundation for fighting the Ebola virus. They have also donated $75 million to San Francisco General Hospital — which has since been named after Zuckerberg — through the Silicon Valley Community Foundation.

In an effort to improve public education, Zuckerberg and Chan decided in 2014 to donate $120 million to schools in the Bay Area. Four years earlier, they had pledged $100 million to the public school system in Newark, New Jersey.

Through the Chan Zuckerberg Initiative, which was founded in December 2015 to advance the couple's goals in healthcare and education, the pair also pledged to donate at least $3 billion over the next decade to "cure all disease" by the end of the 21st century.

Oracle Corporation co-founder Larry Ellison, who signed the Giving Pledge in 2010, has donated millions to educational and healthcare causes through the Lawrence Ellison Foundation.

In a letter announcing his participation in the pledge, Ellison wrote that he has given hundreds of millions of dollars to medical research and education, and he intends to donate billions more in the future. According to the Bloomberg Billionaires Index, Ellison's net worth is currently $55.3 billion.

Among his donations, Ellison has given $200 million to cancer research and $100 million toward ending polio.

Microsoft co-founder Paul Allen, who signed the Giving Pledge in 2010, has focused his philanthropic efforts on science research, from preventing epidemics to saving species from extinction.

He founded the Allen Institute for Brain Science, which studies the genetic causes of brain cancers and other diseases, and has invested roughly $500 million in the research facility. In 2014, he pledged $100 million to fight the Ebola outbreak in West Africa.

Allen has donated $2 billion to philanthropy, according to financial research company Wealth-X. The Bloomberg Billionaires Index puts Allen's net worth at $26.5 billion.

Tesla CEO Elon Musk has donated primarily toward science and engineering education, renewable energy research, pediatric research, and human space exploration research.

Musk signed the Giving Pledge in 2012, and his Musk Foundation donates between $175,000 and $600,000 per year, according to Forbes.

In 2011, when a tsunami devastated Soma City in Japan, the Musk Foundation donated $250,000 to build a solar power system there. Last year, Musk donated $15 million to Global Learning, a program run by the nonprofit XPRIZE to develop software that can help children in developing countries teach themselves basic math and literacy skills.

His net worth, according to the Bloomberg Billionaires Index, is $21.7 billion.

Asana CEO Dustin Moskovitz and his wife, Cari Tuna, signed the Giving Pledge in its first year.

In 2011, Moskovitz and Tuna co-founded the Good Ventures Foundation, which partners with GiveWell and the Open Philanthropy Project to find causes to support.

Some of the foundation's recent grants have gone toward reforming the criminal justice system, farm animal welfare, and biosecurity. According to its website, Good Ventures provided $314 million in grant funding last year.

Moskovitz's net worth is currently $17.1 billion, according to the Bloomberg Billionaires Index.

Indian business tycoon Azim Premji, chairman of the IT services company Wipro Limited, is working to improve public education in India through his foundation, which has opened a nonprofit university focusing on education and human development.

Before signing the Giving Pledge in 2013, Premji donated about 8.7% of Wipro Limited's total stock — then valued at roughly $2 billion — to create an endowment for the Azim Premji Foundation. His net worth is currently $15.3 billion, according to the Bloomberg Billionaires Index.

According to Wealth-X, Premji donated another $2.2 billion to the foundation in 2012, followed by $3.8 billion more in 2015.

German businessman Hasso Plattner, co-founder of software company SAP SE, launched a foundation roughly 20 years ago to focus on global health and education.

In 2005, he donated $35 million to the Hasso Plattner Institute of Design at Stanford University. He signed the Giving Pledge in 2013, and the Bloomberg Billionaires Index estimates his wealth to be $14 billion.

Plattner also co-founded the Wildenstein Plattner Institute in 2016 to digitize historical art materials like artists' correspondence and stock books from art galleries.

Earlier this year, Plattner's foundation donated roughly $4.9 million to the Lucian Blaga University of Sibiu, which is in Romania.