What Is Machine Payments Protocol (MPP)? Created by Stripe and Tempo

The Problem: Agents Can't Pay for Things

AI agents can write code, generate images, and build entire applications. But they can't pay for anything.

Want your coding agent to buy a domain name? It sends you a link to open in your browser. Need it to hit a premium API? You create an account, generate an API key, paste it into a config file. The whole point of an agent is that it handles things for you — but the payment layer keeps pulling humans back in.

Machine Payments Protocol was built to fix that. Launched in March 2026 by Stripe and Tempo, with a big contribution from Visa, MPP gives AI agents a way to pay for APIs, compute, and digital services without ever leaving the command line.

How MPP Works: Payment-Method Agnostic by Design

Most agentic payment tools pick a side. They work with stablecoins, or they work with cards. Not both. MPP doesn't pick a side.

Today it supports three payment methods through one protocol: stablecoins on Tempo, Lightning Network, and credit or debit cards via Stripe. The agent requests a resource, the server responds with a price and accepted methods, the agent pays. No browser. No checkout page. No human in the loop.

“There's not really a good, low-level primitive that's payment rail agnostic. It's either very oriented towards cards, or very oriented towards stablecoins. So what we did is we looked at the 402 payment required code and said, what would be truly the most general, neutral, abstract implementation of a payment method agnostic protocol?”

— Liam Horne, Head of Product at Tempo (Episode 75)

Under the hood, it builds on HTTP 402 — the “Payment Required” status code that was reserved in the original HTTP spec but never actually used. When an agent hits an MPP endpoint, the server returns a 402 with payment options. The agent picks one, pays, gets the resource.

And that last part matters. Tempo designed it to be precise enough for adoption as an IETF internet standard. Not just another crypto protocol — something the whole industry could use.

Why Visa Built a CLI for Machine Payments

Within weeks of seeing the MPP spec, Visa's crypto team built Visa CLI — a command-line tool that lets developers make real card transactions over MPP directly from Claude Code or any coding agent.

“We had multiple engineers in the office over the weekend. We were just cranking it up — how do we take this spec and adapt it so that it can work for any card network, any PSP, any vault provider. We put out the spec, we wrote the SDK, and then we built a working end-to-end experience called Visa CLI that is making live transactions over MPP card.”

— Cuy Sheffield, Head of Crypto at Visa (Episode 75)

Cuy Sheffield has been using his personal Visa card to buy image generation and music creation from the command line. No browser, no subscription, no API key. And that's the point — developers who don't want to hold stablecoins can still do agentic commerce through their existing cards.

“Our belief is the only way agentic commerce is going to scale is if it's payment method agnostic, payment network agnostic, PSP agnostic. This is too big of a market to say the winning solution is going to be one chain, one company — it just isn't going to work.”

— Cuy Sheffield, Head of Crypto at Visa (Episode 75)

MPP Sessions: The “Bar Tab” for Micropayments

MPP has a feature called sessions that handles high-frequency micropayments without doing individual on-chain transactions for each one.

Think of it like a tab at a bar. An agent locks up $5 at the start of a session with a service. Over the next hour, it makes hundreds of tiny payments that draw down from that balance. When the session ends, unused funds come back.

“You lock up, say, five dollars because you anticipate spending up to five dollars over the next hour. And over the course of the next hour, you then make small incremental payments that draw down from the five dollars. Instead of doing hundreds of payments of like a cent each, you do one locking of funds — one on-chain transaction — and then hundreds of micropayments, each of which are pretty much instant and completely free.”

— Liam Horne, Head of Product at Tempo (Episode 75)

The obvious use case is paying for LLM tokens. Each token costs a fraction of a cent. You don't want an on-chain transaction for every one. Sessions batch micro-interactions into a single settlement while keeping individual payments instant and peer-to-peer.

This isn't new. It's an evolution of payment channels, which have been in blockchain research since 2017. But as Liam noted, nobody needed them until now. AI agents doing millions of sub-cent transactions per minute are the exact use case payment channels were built for.

MPP vs x402: How They Compare

If you've been following the x402 protocol, you might be wondering how MPP fits in. Both protocols are inspired by the same HTTP 402 status code, and both aim to make internet payments native for machines. But they take different approaches.

x402 was one of the first protocols to use 402 for stablecoin micropayments. It does one thing well: letting AI agents pay for API access with stablecoins on Base and other EVM chains. It works today.

MPP goes broader. It's payment rail agnostic from the start — doesn't care whether you pay with stablecoins, Lightning, or a Visa card. It also has the sessions primitive for batched micropayments, and it's aiming for IETF-level standardisation.

They're not necessarily competitors. MPP took lessons from x402 directly:

“It's exciting to be able to work with Stripe. They obviously have lots of years of experience building payments, and also taking a lot of lessons learned from things like x402, that's begun some of the micropayment interactions. We designed a protocol that we think is going to be very long-lasting and acceptable by even bodies like the IETF.”

— Liam Horne, Head of Product at Tempo (Episode 75)

In practice: x402 gives you stablecoin micropayments right now. MPP gives you a protocol that works across every payment method — but it's newer and the tooling is still being built out.

Why Vibe Coders Are the First Users

The first people using MPP aren't enterprises or payment processors. They're vibe coders — developers who live inside Claude Code, Cursor, and other AI coding agents, building apps without leaving the command line.

Every time an agent needs a premium API, a font, a domain name, or an image generation service, the developer gets kicked out of their flow to sign up and manage billing. MPP gets rid of that.

“If your agent comes back and says, you need to click on this link, open this website, paste in a bunch of details, create an account, sign up with Google, copy and paste this API code into a .env file — it's just annoying. The whole idea of agentic workflows is that it should just work. You should just talk to the agent and never leave the agent flow.”

— Liam Horne, Head of Product at Tempo (Episode 75)

Cuy Sheffield saw a split in how people reacted. Developers who use Claude Code daily got it immediately. People who haven't tried command line commerce had no idea why it mattered.

“People are discovering new services through MPP. Someone said, I would never have gone to Grok and paid for the API just to get access to the Twitter data. But because I can do it in a micropayment, it's super useful. People are discovering services they never would have subscribed to, and it's creating competition.”

— Simon Taylor, co-host of Tokenized (Episode 75)

That pattern — micropayments unlocking demand for services people would never subscribe to — might be more important than the protocol itself. MPP isn't replacing existing payments. It's creating markets that couldn't exist under subscription models. And that's a much bigger deal.

Kill the API Key

Right now, accessing most paid services on the internet means creating an account, generating an API key, and managing credentials. For agents, that's a dead end.

MPP replaces the API key with a payment. No pre-registration, no authentication flow. The agent pays for what it needs at the point of request. Payment is the authentication.

“I hate leaving the command line. I hate getting API keys. I want to kill the API key. And so this idea of command line commerce — there's a segment of customer that's like, this is solving one of the biggest pains.”

— Cuy Sheffield, Head of Crypto at Visa (Episode 75)

Simon drew the Stripe parallel directly. When the Collisons were fundraising, they told investors their customer didn't exist yet. The developer who needed to accept payments with a few lines of code — that person only emerged because Stripe removed the friction. MPP is doing the same thing for agentic commerce. The use cases show up once you get the friction out of the way.

AI Developers Are Already Using It

One big question: will AI developers — many of whom have no interest in crypto — actually use blockchain-based protocols? Raj Parekh, CEO of Monad, sees it happening on the ground in San Francisco.

“When you go to these meetups and hackathons, you actually don't see crypto devs. You see a lot of AI, web two devs that are playing with this technology. For the first time, you're seeing these devs have that eye-opening moment where they can say, oh wait, this is actually digital native money that actually moves, and I can interact with it using the CLI.”

— Raj Parekh, CEO of Monad (Episode 75)

MPP doesn't force developers to “go crypto.” Want to use your Visa card through MPP Card? Fine. Prefer stablecoins? Pay on Tempo. It meets developers where they are instead of asking them to adopt a new financial system.

What's Next

MPP launched with a working implementation, a public spec at mpp.dev, and a companion spec at payment-auth.org. Over 100 developers were at the launch hackathon building MPP-enabled services.

Next steps: get as many services as possible to add MPP endpoints so agents never need to leave their workflow. Monad is shipping its own MPP extension. Visa is expanding Visa CLI beyond internal testing.

The question is whether MPP becomes the standard everyone converges on, or one of several competing protocols. Having Stripe, Tempo, and Visa as co-developers gives it weight that most crypto protocols don't have. And because it's payment method agnostic, it doesn't ask anyone to pick a side. That matters.

Simon's take on this might be the best summary: the future of commerce isn't putting a checkout inside the LLM. Agents don't want a checkout on a web page. They want something clean and simple. That's what MPP is.

“For a long time, people have been trying to put the checkout inside the LLM. But the agent doesn't want a checkout on a web page. Agents like markdown, they like CLIs, and they like very simple internet-native protocols. What agents want is something really clean and really simple — and that's what MPP delivers.”

— Simon Taylor, co-host of Tokenized (Episode 75)