announcing MPP Stripe payments for agents

MPP (Machine Payments Protocol) is a protocol for machine-to-machine payments backed by Stripe. where x402 uses crypto wallets and on-chain settlement, MPP lets agents pay via card charges through Stripe — no wallet required.

the protocol works like x402 at a high level: the server returns HTTP 402 with a payment challenge, and the agent responds with a payment credential. the difference is the payment rail — Stripe instead of blockchain.

x402 requires agents to have a crypto wallet funded with USDC on Base. that's a real barrier for agents that don't operate in the crypto ecosystem.

MPP lets agents pay with Stripe credentials — a lower barrier for teams that already have Stripe set up. same pricing ($0.50 per launch beyond 5 free/month), same free tier, same rate limits. just a different payment rail.

both protocols coexist. when an agent hits a 402, the response includes challenges for both x402 and MPP. the agent picks whichever protocol it supports.

the flow mirrors x402 with a different auth header:

1. agent calls a launch endpoint with no payment proof
2. dropspace returns 402 with both an x402 object (crypto challenge) and an mpp object (Stripe challenge) in the response body, plus a WWW-Authenticate: Payment header
3. the agent picks MPP and retries with an Authorization: Payment <base64url-credential> header
4. dropspace verifies the credential via Stripe and processes the request

within the free tier (5 launches/month), the credential is used for identity only — no charge is made. beyond the free tier, Stripe settles the $0.50 charge.

• x402 — your agent has a crypto wallet and you want on-chain settlement in USDC on Base
• MPP — your agent has Stripe credentials and you want card-based payment without touching crypto

both protocols share the same price, free tier, and rate limits. the only difference is the payment rail and the auth header format.

MPP is available today on all launch endpoints. check the agent payments docs for the full protocol comparison, example requests, and 402 response shapes for both protocols.

if you're already using x402, nothing changes — your existing integration continues to work. MPP is an additional option for agents that prefer Stripe over crypto.

for the crypto path, see the x402 announcement for background on how x402 works with dropspace.