Jan 19 (Reuters) - Autograph, a non-fungible token (NFT) platform, on Wednesday said it had raised $170 million in fresh capital from a funding round led by venture capital firms Andreessen Horowitz and Kleiner Perkins. The startup, co-founded by National Football League quarterback Tom Brady last year, operates an NFT platform that features collections from popular celebrities across sports, entertainment and culture. Athletes Naomi Osaka, Tiger Woods, Simone Biles, Tony Hawk and Usain Bolt are among its board of advisors. NFTs are digital assets which exist on the blockchain, a type of digital ledger, and they have exploded in popularity over the last year with people splurging on artworks and video highlights from sports games as NFTs. Los Angeles-based Autograph"s latest capital raise comes six months after its Series A round. It had then raised $35 million at a pre-money valuation of $700 million, according to data from PitchBook. Other investors in the Series B round announced on Wednesday include former Andreessen Horowitz general partner Katie Haun"s new fund, existing investor 01A, and Nicole Quinn, partner at venture firm Lightspeed Venture Partners. In July, Autograph entered partnerships with global content behemoth Lionsgate and digital sports entertainment company DraftKings Inc .