The Battle for the Internet's Payment Layer
Plus, the SEC reveals a taxonomy for crypto
Olivia Capozzalo & Camila Russo
March 18, 2026
gm, Defiers!
Today’s big story:
- Two protocols are racing to become the foundation of AI payments: x402, backed by Coinbase, and the Machine Payments Protocol (MPP), launched today by Stripe and Tempo.
In other news:
- SEC clarifies securities law for crypto
- OpenSea delays token launch, again
- Mastercard acquires BVNK
- WhiteBIT and 10 Other Firms Enter Ghana's First Crypto Regulatory Sandbox [MEDIA PARTNER]
Read more below! But first, please give our sponsors some love; they make this newsletter possible.
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We’re back! Here’s what you need to know in web3 today
📈 Markets in the Past 24 Hours
| TICKER | VALUE | 24H | |
|---|---|---|---|
 | Bitcoin | $71,395 | -3.91 % |
 | Ethereum | $2,193.83 | -5.82 % |
 | XRP | $1.45 | -5.18 % |
 | BNB | $648.77 | -3.33 % |
 | Solana | $89.41 | -5.28 % |
Today’s Big Story
The Battle for the Internet's Payment Layer
Crypto was supposed to be the payment layer of the internet, and the industry has certainly made progress getting there. But the rise of AI in the past few months is bound to accelerate that transformation.
Agents need to pay for things. Not once a month on a subscription. Not with a card tied to a human who has to approve each charge. Constantly, autonomously, in milliseconds, for API calls, compute, data and services no human would ever manually authorize. The old payments infrastructure simply wasn't built for this.
And now two protocols are racing to become the foundation of what comes next: x402, backed by Coinbase, and the Machine Payments Protocol (MPP), launched today by Stripe and Tempo.
What Dropped Today
Tempo, the payments-focused L1 blockchain incubated by Stripe and Paradigm, went live on mainnet this morning, and with it came MPP, an open standard for agent-to-service payments co-authored with Stripe.
The headline feature is a "sessions" primitive: agents authorize a spending limit upfront, then stream micropayments continuously without an on-chain transaction per interaction. Think of it like opening a tab. Visa has already extended MPP to card payments, Lightspark to Bitcoin Lightning. Stripe's full payments stack, including fraud protection, tax, and accounting, plugs in natively.
On the same day, Coinbase dropped a significant upgrade to x402: the protocol now supports virtually any ERC-20 token. Until today, x402 was largely built around EIP-3009, which meant it worked great for USDC and not much else. The fix uses Uniswap's Permit2 plus two new gas sponsorship extensions, making the experience fully gasless for end users. Developers can now accept USDT, DAI, native project tokens, in-game currencies, anything on any EVM chain, without users needing to hold ETH or bridge assets.
The Short Version
x402 is more permissionless. MPP is more payments-optimized.
That's the cleanest way to frame it. But what that actually means in practice is worth unpacking.
Where They Actually Differ
Asset flexibility: After today's update, x402 is genuinely token-agnostic across EVM chains. MPP runs on Tempo and accepts stablecoins plus fiat — cards, wallets, BNPL. x402 will never natively speak Pix or Visa. MPP won't accept your obscure DeFi token. These are different bets about what the agentic internet actually runs on.
The auth/settlement split: MPP's sessions primitive is a genuine architectural advantage for machine-scale payments. Agents authenticate once, spend freely within a limit, and settle later in a batch. x402 is more per-request today; pay, get resource, repeat. It's working on an "upto" scheme that would change this, but it hasn't shipped. For throughput at true agent scale, MPP is more thoughtfully designed.
Intermediary dependence: x402 works peer-to-peer. The Coinbase facilitator is optional. Anyone can run one, and the protocol doesn't break without it. MPP requires Tempo and Stripe. That's not a bug to the MPP team; it's how they get fiat rails and institutional trust. But it's a meaningful difference in philosophy, and it matters even more when you take into account that the Tempo blockchain is currently permissioned. So effectively, Stripe and its blockchain control the settlement rails for this payment protocol.
My Take
If MPP settled on any chain, it would be a clear winner. The fiat support, the sessions model, and the Stripe integration are real advantages that x402 doesn't have yet. But tying the protocol's future to Tempo and Stripe undercuts everything that makes an open standard worth rallying around. The whole point of a protocol is that it outlives any single company's incentives.
That said, I'll be honest, if I were adding micropayments to The Defiant today, I'd probably go with MPP. The fiat acceptance matters for reaching audiences beyond crypto natives, and I already manage payments on Stripe, so it would easily integrate with my current workflow and tools.
In the end, if most businesses make that decision, that will matter more for adoption than how decentralized and permissionless a protocol is.
I still hope Tempo doesn’t force us to make that tradeoff.
With love,
Cami, founder of The Defiant
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🎬WATCH
Will Aave’s New Plan Change DeFi Forever? | Stani Kulechov Explains
In this episode of The Defiant Podcast, Cami sits down with Aave founder Stani Kulechov.
Aave is navigating a pivotal moment with the recent "Aave Will Win" proposal. This initiative aims to redirect 100% of protocol revenue back to the Aave DAO, a move that many in the community have embraced. But with any major change comes scrutiny.
Watch the full interview:
Top News in the Past 24 Hours
SEC Clarifies How Federal Securities Laws Apply to Crypto Assets
The U.S. Securities and Exchange Commission and the Commodity Futures Trading Commission have jointly released a sweeping interpretive guidance that formally classifies major crypto assets and activities under federal securities law.
Why it matters: This represents a watershed moment for the crypto industry, ending years of regulatory ambiguity and "regulation by enforcement” in the U.S.
OpenSea Delays Token Launch Again, Citing Market Conditions
OpenSea has pushed back the launch of its long-awaited SEA token for the second time, with co-founder and CEO Devin Finzer announcing Monday that the previously planned March 30 token generation event will not go ahead as scheduled.
Why it matters: The SEA token has been dangled in front of OpenSea users for the better part of two years; The response from the community has been predictably sour, though muted.
Mastercard to Acquire Stablecoin Infra Firm BVNK for up to $1.8 Billion
Mastercard has struck a deal to buy stablecoin infrastructure firm BVNK for up to $1.8 billion, including $300 million in contingent payments.
Why it matters: The move aims to integrate BVNK’s stablecoin infra into Mastercard's network to bridge on-chain payments and existing fiat rails.
Trending on The Defiant
- SEC Clarifies How Federal Securities Laws Apply to Crypto Assets
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- Centrifuge's CFG Token Surges 60% on Binance Listing
- CoW Swap Points to Legacy Code and Solver Failures in $50M Loss That Aave Attributes to Illiquid Market
- World Liberty Financial Passes Proposal Offering Team Access for Top Stakers
- Crypto Wealth Manager Abra to Go Public via SPAC Merger
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