Y Combinator-backed savings and investment app Gullak has raised $3 million in its seed funding round from investors including Rebel Partners and Better Capital. CRED Founder Kunal Shah, Goodwater Capital and TRTL Ventures were among the other investors that participated in the round. In its pre-seed round, Gullak had raised $1.3 million from Uni Cards CEO Nitin Gupta and others.