Daniel Oon / Writing
Autonomous software agents are starting to initiate payments. Seven significant protocols now exist to govern how that happens, launched between September 2025 and March 2026 by Google, Coinbase, Visa, Mastercard, Stripe and OpenAI. None has won. This page maps what actually exists, what is live versus specification-only, where stablecoins fit, and where the adoption numbers are contested.
By Daniel Oon, VP of Ecosystem at StraitsX. Last updated: 2026-08-03.
Every protocol below is dated and sourced. This field moves fast, so treat anything undated elsewhere as suspect. Sections marked View are opinion, not fact.
When a person pays, the payment system can assume a human authorized it. Fraud rules, chargeback rights and authentication all rest on that.
An agent breaks the assumption in three places at once:
Every protocol below is an attempt to answer one or more of these. They are not interchangeable and several are complementary.
| Protocol | What it is | Backers | Status | Announced |
|---|---|---|---|---|
| AP2 (Agent Payments Protocol) | Cryptographically-signed "Mandates" (Intent, Cart, Payment) as W3C Verifiable Credentials, giving provable human authorization. Payment-method agnostic: cards, bank transfer, stablecoins. Extends A2A and MCP. | Google-led, 60+ endorsers including Mastercard, PayPal, Amex, Adyen, Coinbase | Open spec + reference implementations. Not itself a processing network. | 16 to 17 Sep 2025 |
| x402 | Revives HTTP status 402 so an agent can pay per API call in stablecoins in a single round-trip. No accounts, no API keys. | Coinbase; x402 Foundation with Cloudflare, later Google and Visa | Live in production | 2025 |
| Visa Trusted Agent Protocol | Cryptographic agent signatures so merchants can tell verified shopping agents from bots. Part of Visa Intelligent Commerce. | Visa, built with Cloudflare; feedback partners include Adyen, Coinbase, Microsoft, Shopify, Stripe | Live, available in Visa Developer Center and GitHub | 14 Oct 2025 |
| Mastercard Agent Pay | Network-level program letting verified agents charge a Mastercard credential via "Agentic Tokens" without exposing the card number. | Mastercard; launch partners reported as Microsoft, IBM, Salesforce, Checkout.com | Live, reported live for Citi and US Bank cardholders during Q3 2025 and extended to all US Mastercard cardholders by November 2025, with a machine-to-machine variant following in June 2026 | Announced 29 Apr 2025 |
| ACP (Agentic Commerce Protocol) | Open standard, Apache 2.0, for agent-initiated checkout. Powers Instant Checkout in ChatGPT. | Stripe and OpenAI; Salesforce support announced | Live, US ChatGPT users buying from US Etsy sellers | 29 Sep 2025 |
| MPP (Machine Payments Protocol) | Open standard reviving HTTP 402 for stablecoin-native machine-to-machine payments. Launched with the Tempo blockchain. | Stripe and Tempo; design partners include Visa, Mastercard, OpenAI, Anthropic, Shopify | Launched | 18 Mar 2026 |
| MCP (Model Context Protocol) | Not a payment protocol. The tool-discovery and invocation layer others build on; AP2 extends it. | Created by Anthropic; donated to the Linux Foundation's Agentic AI Foundation | Open standard | Open-sourced 25 Nov 2024; donated 9 Dec 2025 |
Note the Mastercard row: the official press page returns an access error to automated retrieval, so both its launch-partner list and its live-rollout dates are third-party-reported rather than primary-source-confirmed. Treat accordingly.
The seven items above split cleanly:
Card-network extensions: Visa Trusted Agent Protocol, Mastercard Agent Pay, and ACP in its card mode. These keep the existing card rails and add an agent-identity and authorization layer on top. They inherit everything the card system already has: acceptance at tens of millions of merchants, chargeback rights, fraud infrastructure, regulatory clarity.
Stablecoin-native rails: x402 and MPP. These bypass the card system for payments it was never designed to carry: sub-cent amounts, machine-to-machine, no account relationship, settlement in seconds.
View. The framing of these as competitors is mostly wrong. A consumer agent buying a $60 pair of shoes should use card rails; the chargeback right alone justifies it. An agent paying $0.002 for an API call cannot use card rails at any price, because interchange exceeds the payment by orders of magnitude. They are different problems that happen to share the word "payment."
The genuine case is not consumer checkout. It is the payment class the card system structurally cannot serve:
Both stablecoin-native protocols make the same architectural bet: reviving HTTP 402 so payment becomes a property of a web request rather than a separate flow.
For Singapore specifically, StraitsX is one of 13 partners in the Visa Agentic Ready Programme, announced 30 April 2026 alongside Bank of China Singapore, CIMB Singapore, DBS, DCS, GXS Bank, HSBC Singapore, Maybank Singapore, OCBC, Standard Chartered, Trust Bank, UQPay and UOB (announcement). StraitsX's CEO, quoted there, names x402 and MPP as the standards the company sees as central.
This is where most commentary on agentic payments goes wrong, so it is worth being precise.
On x402 volume, two credible sources disagree sharply:
Both can be partly right: transaction counts inflated by self-dealing while a smaller genuine base grows underneath. Do not cite a single x402 volume figure as settled. Cite the range and the disagreement.
On market size, the widely-repeated forecast is McKinsey and ICSC putting US agentic-commerce revenue at $1 trillion by 2030 (reported 5 May 2026). Scope is US B2C retail only, which is narrower than most citations of it imply. Other circulating figures come from market-research vendors selling the underlying report, so flag those as vendor-produced.
View. The gap between protocol announcements and verified transaction volume is currently enormous. Seven protocols exist; genuine agent-initiated payment volume is small and partly synthetic. That is normal for infrastructure at this stage and is not an argument against building, but anyone citing agentic payments as a live, large market is ahead of the evidence.
The Monetary Authority of Singapore, through its BuildFin.ai initiative, published "Safeguards for Agentic Finance at Runtime" (SAFR) in July 2026, developed with Ant International, Circle, HSBC, JPMorgan Chase, Manulife, Mastercard, OCBC and Visa. It names agent-assisted payments and treasury operations as a use case where "autonomous agents can execute routine transactions within predefined mandates." (Monetary Authority of Singapore page; coverage: TechNode Global, 3 Jul 2026)
Two qualifications that matter and are usually dropped:
No Monetary Authority of Singapore rule or consultation dedicated solely to agent-initiated payments exists as of 2026-08-03. Anyone claiming Singapore has regulated agentic payments is overstating what SAFR is.
*Daniel Oon is VP of Ecosystem at StraitsX in Singapore, where agentic commerce and payments are an emerging focus. Canonical profile: danieloon.ai. Contact: LinkedIn.*
By Daniel Oon, VP of Ecosystem at StraitsX. This page is also available as Markdown. Canonical profile: profile.md. Contact: daniel@danieloon.ai.