Infosys co-founder and tech billionaire Nandan Nilekani and his wife Rohini Nilekani have joined ‘The Giving Pledge’, an elite network of the world’s wealthiest individuals committing half their wealth to philanthropy.The Giving Pledge website uploaded Nilekanis’ letter signing up for the cause.The letter said, “We thank Bill and Melinda for creating this unique opportunity to realise a moral aspiration inspired by the Bhagwad Gita – ‘Karmanye Va dhikaraste Ma Phaleshu Kadachana, Ma karma phalaheturbhurma Te Sangostvakarmani’.”“We have a right to do our duty,but no automatic right to the fruits from the doing. It is critical that we do not slip into inaction fearing that we may not be able to reap direct reward. It is to this ideal that we pledge,” it added.Later Bill Gates tweeted on his handle about Nilekanis’ pledge on his twitter handle on Monday.“I’m amazed by how @NandanNilekani has lent his entrepreneurial passion to philanthropy. I’m delighted to welcome him and his wife Rohini to the Giving Pledge,” Gates tweeted.A Forbes report pegged the Nilekanis’ wealth at $1.7 billion.The Giving Pledge was created by Bill and Melinda Gates and Warren Buffett in August 2010 following a series of conversations with philanthropists around the world about how they could collectively set a new standard of generosity among the ultra-wealthy. The Nilekanis are the fourth Indians after Wipro chairman Azim Premji, Biocon chairman Kiran Mazumdar-Shaw and Sobha Developers Chairman Emeritus PNC Menon to sign up, and bring the total number of donors to 171 from 21 countries.“Our philanthropic journey of two decades has been led by Rohini’s passion and commitment!” Nilekani tweeted.Talking about their initiatives as EkStep, Nilekanis’ letter said, “We are excited by our initial experimentation with societal platforms in early education and see immense potential for scaling up diverse solutions.”The couple also said their philanthropic efforts would be directed at societal platforms, which are open, technology enabled ecosystems or nurturing networks.Nilekani recently returned to Infosys as Non-Executive Chairman after the exit of Sikka as Infosys CEO.Sikka quit following a long-standing feud between board and founders, especially NR Narayana Murthy, who had raised concern over falling corporate governance practises at Infosys.Rohini is also founder of Arghyam, an initiative for safe and sustainable water.