Steve Kaliski

Steve Kaliski is a principal software engineer at Stripe and engineering lead for agentic commerce, developing payment infrastructure that allows autonomous software to make purchases within limits established by people and businesses. His work includes the technology behind ChatGPT’s Instant Checkout and emerging protocols for secure agent-driven transactions.

Kaliski studied at New York University and spent his first four years at Stripe leading work on Stripe Issuing, which enables businesses to create physical and virtual payment cards through an API. Reflecting on his first 1,000 days building Issuing, he emphasized operational transparency: developers need to understand card-network behavior, authorization failures, and banking relationships when financial products malfunction.

He subsequently turned to the infrastructure required when software, not a human cardholder, initiates a purchase. As engineering lead for Stripe’s collaboration with OpenAI, Kaliski helped develop Instant Checkout in ChatGPT and the Agentic Commerce Protocol, announced in September 2025. He has also described his involvement in secure credential sharing and the merchant integrations required to make conversational checkout practical.

Building enforceable boundaries for autonomous buyers

• Deterministic payment boundaries: Agents can explore products and services freely, but payment credentials, checkout terms, and spending authorization require explicit, enforceable controls. Kaliski identifies impersonated merchants, incorrect purchases, unexpected prices, and exposed credentials as distinct infrastructure risks.

• Shared Payment Tokens: These scoped credentials restrict transactions by seller, amount, currency, and expiration while preserving merchants’ existing fraud checks and Stripe PaymentIntents integrations.

• Agentic Commerce Protocol: Developed with OpenAI, this standard structures exchanges between agents and sellers around product catalogs, cart contents, taxes, shipping, and checkout updates. Merchants retain authority over inventory, pricing, customer relationships, and transaction-risk decisions.

• Machine Payments Protocol: Kaliski coauthored Stripe’s March 2026 introduction of this standard, developed with Tempo. Its HTTP 402 payment challenges communicate the price, recipient, and payment mechanism for protected online resources, enabling agents to purchase API access or other services through stablecoins and conventional payment infrastructure.

Kaliski also represents Stripe on the x402 technical steering committee, contributing to interoperable standards for software that earns, spends, and transacts under verifiable human and business constraints.