Original Title: Stripe's MPP vs. x402: What Actually Happened Today
Original Author: Nick Sawinyh, defiprime.com
Translator: Peggy, Blockbeats
Editor's Note: Regarding how agents make payments, x402 and MPP offer two nearly opposite pathways.
x402 adopts protocol minimization: embedding payments directly into HTTP requests, implementing pay-per-request in the simplest way. No accounts, no intermediaries, resembling the open, permissionless designs of the early internet, suitable for long-tail developers and decentralized scenarios.
MPP, on the other hand, is about system maximization: addressing high-frequency trading, risk control, and fiat access issues through sessions, streaming payments, and compliance systems. It does not seek purity but prioritizes meeting real commercial needs, making it more suitable for enterprise-level and large-scale applications.
The difference between the two is essentially two solutions to the same problem: whether to make payments a part of the protocol or a layer of the system.
Therefore, they are not in complete competition but are more like different segments; x402 covers the long-tail needs of the open network, while MPP handles high-frequency and commercial traffic. In an emerging agent economy, this differentiation may be inevitable.
Here is the original text:
HTTP status code 402 has been defined in the HTTP/1.1 specification since the late 1990s, waiting for a place to be put to use. Its meaning is payment required. The initial idea was to embed payment capabilities into the protocol layer of the web, allowing machines to purchase resources just like requesting web pages.
However, this idea has mostly not been realized. Over the years, this status code has only occasionally appeared in marginal scenarios, such as Shopify's throttling responses and billing errors from Apple Mobile Me, but no one has truly built the micropayment future it implies. Instead, credit cards, subscription payment walls, and API Key mechanisms have taken its place, systems fundamentally designed for humans who perform manual operations.
Today, this future has emerged in two competing implementation paths, released on the same day. Next, I want to outline what they are, their differences, and why Stripe has made simultaneous bets on both routes.
x402: A Simpler Solution
Coinbase officially launched x402 in May 2025 with a core idea that can be described as almost radical in its simplicity. A client requests a resource; the server returns HTTP 402 and informs the client how much needs to be paid, which token to use, and on which chain to make the payment. After the client completes the payment on-chain, they attach the payment certificate to the reinitiated request, and the server promptly delivers the resource.
It's that simple. No account system, no API Key, and no subscription mechanism. Just a round trip of an HTTP request with a payment inserted in the middle.
Now, Stripe has natively supported x402 in its payment system, allowing merchants to accept such payments directly through their existing backend. However, at its core, x402 is still a protocol led by Coinbase, governed by the x402 Foundation co-founded with Cloudflare in September 2025. The protocol is completely open-source (Apache 2.0 license) and provides multi-language SDKs in TypeScript, Go, and Python.
In terms of support range, Coinbase's official documentation indicates that it currently supports ERC-20 payments on Base, Polygon, and Solana. The ecosystem is also exploring its extension to other chains like Avalanche, Sui, and Near, but maturity varies.
Looking at adoption data, this part is a bit more complex. Coinbase states that x402 has processed over 50 million transactions through its Agentic Wallet infrastructure. It sounds impressive, but according to CoinDesk's March 11 reference to on-chain analysis data from Artemis: daily transaction volume is about 131,000, with a total amount of approximately $28,000, and the average payment per transaction is only about $0.20, with roughly half resembling testing or gamified behavior rather than genuine commercial transactions.
However, this may not be a bad thing. Because this protocol was designed for a market that hasn't truly existed yet, a world where AI agents make micro-payments (even less than one cent) for API calls and data queries. The merchants serving this market are only just beginning to emerge.
For example, Google’s Agentic Payments Protocol (AP2, part of the A2A framework) has integrated x402; Lowe's Innovation Labs has also showcased a demo: an AI agent can complete the entire process from product discovery and research to placing an order in one flow. Meanwhile, World (initiated by Sam Altman) released AgentKit this week to enhance x402 wallet with human identification capabilities.
The core assumption behind this is that as long as payments are made as lightweight as HTTP requests, application scenarios will naturally emerge. Whether this holds true remains to be validated.
MPP: A Full-Stack Solution
Stripe and Tempo have chosen a different path. The Machine Payments Protocol (MPP) was released today alongside the Tempo mainnet. Unlike x402, which acts as a lightweight encapsulation layer on existing blockchains, MPP is designed specifically for the high-frequency trading scenario of agents.
Its core mechanism is sessions. Unlike needing to initiate an on-chain transaction for every resource request, an agent can authorize a spending limit once and then make micropayments continuously within that limit. If you're an AI that needs to query thousands of data sources every hour, you definitely wouldn't want to sign and broadcast an on-chain transaction every time, and sessions are designed to solve this issue.
The Tempo chain is also built around this need. It supports tens of thousands of transactions per second, has sub-second confirmation times, and has no native gas token. Users can directly pay transaction fees with stablecoins, eliminating the cumbersome steps of purchasing some random token for transfer.
Another component worth understanding is that Stripe's Agentic Commerce Suite includes Shared Payment Tokens (SPTs). This is not part of MPP itself, but is an extension mechanism of Stripe that can be used in conjunction with it. SPT allows agents to securely transmit users' bank card or wallet credentials to merchants without exposing real data. These credentials are limited to single transactions and time-bound, which can be understood as a programmable, self-destructing authorization. In practical use, this means an agent paying through MPP can use either USDC on Tempo or a user-bound Visa card, or even a combination of both.
According to the blog disclosing the Tempo mainnet launch, its partners include Anthropic, DoorDash, Mastercard, Nubank, OpenAI, Ramp, Revolut, Shopify, Standard Chartered, and Visa. The Block also reported that when MPP launched, there were already over 100 services in the payment catalog, including Alchemy, Dune Analytics, Merit Systems, and Parallel Web Systems. Tempo co-founder Matt Huang, in an interview with Fortune, stated that this field is still in the early stages, and the design goal of MPP is to eventually expand to more on-chain environments beyond Tempo.
Why Stripe Supports Both
If you are already integrated with Stripe, the most practical answer is: you don't need to choose between the two.
Stripe supports x402 and MPP through two separate integration paths, rather than abstracting them into a unified interface. For x402, its documentation primarily covers generating recharge addresses, on-chain monitoring, and settling funds to the Stripe account process—you are responsible for returning 402 responses, while the underlying encryption payment infrastructure is handled by Stripe. Currently, it supports USDC on Base, with plans to expand in the future. For MPP, merchants can receive session-based streaming payments through the same PaymentIntents API.
The Agentic Commerce Suite released by Stripe in December 2025 is built on these two payment tracks. Merchants simply upload their product catalog, choose the AI agents they wish to integrate with, and Stripe will take care of product discovery, the checkout process, fraud prevention, and tax processing. Currently, URBN, Etsy, Coach, Kate Spade, and Ashley Furniture are already using it, and platforms such as Wix, WooCommerce, BigCommerce, Squarespace, and commercetools have also completed integrations.
Its strategy is quite clear: control the abstraction layer and let the underlying protocols compete freely.
In Comparison
From a macro perspective, these two protocols are doing the same thing: allowing machines to pay for resources via HTTP. But the real differences lie in the details.
x402 (led by Coinbase) vs MPP (Stripe + Tempo)
Standardization
x402: Completely open-source (Apache 2.0), pushed by the x402 Foundation to promote multi-party participation (Coinbase, Cloudflare, Visa, Google).
MPP: Open standard jointly developed by Stripe and Tempo, part of Stripe's Agentic Commerce Suite.
HTTP Mechanism
x402: Revives HTTP 402, initiating requests through the PAYMENT-REQUIRED header, using PAYMENT-SIGNATURE to complete retries.
MPP: Similarly uses a challenge-response mechanism but employs the Payment HTTP Authentication Scheme (IETF draft), binding challenge IDs through HMAC.
Payment Underlying (Rails)
x402: Designed to be chain-agnostic, currently supports Base, Polygon, and Solana, with other chains still being explored.
MPP: Based on the Tempo blockchain—a payment-optimized L1, supporting over 10,000 TPS, sub-second confirmations, no native gas token; long-term goal is cross-chain compatibility.
Payment Methods
x402: Pure stablecoins, completely on-chain.
MPP: Supports USDC on Tempo + SPT (Stripe's mechanism), enabling a blend of crypto and fiat (credit cards, wallets, BNPL).
Settlement Method
x402: Settles on-chain (approximately 200ms to several seconds), verified and settled by facilitators like Coinbase.
MPP: Tempo sub-second confirmation, Stripe automatically credits accounts and handles compliance.
Merchant Access
x402: Open-source middleware (Express, Hono, Next.js, etc.), can be self-built or use facilitators.
MPP: Directly access Stripe's PaymentIntents API, with risk control, tax, refunds, and reports all built-in.
Core Innovation
x402: Extremely simple, no vendor lock-in, similar to the Unix philosophy in the payment domain.
MPP: High throughput + fiat integration, enabling streaming payments, micropayment aggregation via sessions, and programmable expenditure control based on SPT.
Key Partners
x402: Coinbase, Cloudflare, Google (A2A/AP2), Visa, World, Anthropic (MCP).
MPP: Stripe, Visa, Lightspark, Anthropic, DoorDash, Mastercard, OpenAI, Shopify, Revolut, Standard Chartered.
x402 resembles your preferred option when building an open system: independent developer APIs, decentralized data markets, or any services that do not want to rely on payment processors. Its specification could be written in a white paper, and integration only requires middleware and a wallet address. This purity is quite appealing—though the limitations of pure crypto mean its audience is narrower.
MPP, however, represents an entirely different paradigm. If your agent needs to engage in hundreds or even thousands of transactions within a single session without wanting to go on-chain each time, then it is the more reasonable choice. The session mechanism keeps most interactions off-chain until final settlement; Stripe's compliance framework handles risk control and taxes; and the SPT hybrid model allows agents to go beyond stablecoins to invoke users' Visa and other payment methods directly. It's not as elegant, but it's more grounded in reality.
Interestingly, they are not entirely in competition either. x402 covers long-tail open scenarios, while MPP covers enterprise-level high-frequency traffic. Stripe's strategy is also very clear: it does not bet on a single protocol, but ensures that regardless of which path wins, funds will ultimately flow into Stripe's account system.
The Current Situation: Where Are We Now?
To be honest, there are almost no truly scaled transactions happening right now.
According to Coinbase’s x402 release information, early partners include Hyperbolic (GPU inference payments) and Anthropic (MCP protocol integration). Stripe's blog mentions agent scenarios billed per API call (like CoinGecko). There were over 100 services in the catalog when Tempo launched. Cloudflare's Agents SDK has natively supported x402, and some small projects on Base L2 are also trying to use x402 for payment gateways.
However, overall: transaction volumes are small, merchant numbers are limited, and most activities remain at the experimental stage.
This is actually not surprising. Any new payment infrastructure usually starts this way. The so-called partner lists can vary greatly from signing a letter of intent to going live, and these releases often do not clearly differentiate.
More attention should be paid to the heavyweight participants behind the infrastructure. Stripe processed $1.9 trillion in payments in 2025, with a total volume that grew 34% year-on-year. At the same time, Coinbase, Cloudflare, Visa, Google, and the entire network of partners around Tempo have entered the fray.
In other words, the tracks are already laid. The only question remains: in 2026, will AI agents actually need to make large-scale transactions on this track? Or is this more like laying fiber optics in 1998—demand has not yet arrived, but the infrastructure is ahead of time.
So Which Should You Choose?
If you are building an open, permissionless system—x402 is a more natural choice. No need to register on a platform, no need to connect to payment processors; simply import middleware and bind a wallet to receive payments. The cost is: compliance, risk control, and fiat settlements must be handled yourself.
If you are already within the Stripe ecosystem and wish to access agent traffic—MPP is more suitable. Sessions, streaming payments, a mix of fiat + crypto, and a complete compliance system are essentially more like a configuration upgrade rather than a system reconstruction.
If you only care about one thing: no matter which protocol the agent uses, I can still get paid. Then the answer is actually: use Stripe. It supports both sides.
HTTP 402 has finally come into use. It's just that it has waited nearly 27 years.
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