This paper investigates how cashless payment affects credit access for the underprivileged using Alipay, a BigTech platform that offers various financial services to over 1 billion users. Leveraging a natural experiment and a representative Alipay user sample, I find that cashless payment adoption increases credit access by 56.3% and a 1% rise in payment flow increases credit line by 0.41%. These effects are stronger for the less educated and the older. Counterfactual analysis shows that cashless payment data increase credit lines by 57.7%, consumer surplus by 0.5% of median income, and lender profit by 41.3% of consumer surplus.