Onchain Features · 08 / 8
Software That Pays
Agents buy APIs per call, inline.
The Machine Payments Protocol turns HTTP 402 into a real payment flow: a server names a price, the client pays in stablecoins and retries, and the response comes back with a receipt. Sessions make per-call micropayments cheap; access keys keep agents on a budget.
GET /forecast
402 Payment Required · $0.01
Authorization: Payment ✓
200 OK · receipt
HTTP 0
Native request-pay-retry flow
Source · MPP spec
−0%
Gas for enshrined payment channels
Source · T5
$0.000
Per word, streamed (docs example)
Source · MPP docs
Today vs Onchain
TodayOnchain
Paying for an APISign-up, card, API keyPay per request
MicropaymentsUneconomicOff-chain vouchers, 1 settlement
Agent checkoutHands off to a humanCompletes itself
Spending controlCard limitsScoped, revocable keys
Charge vs Session
Run the requests. A one-time charge settles every call onchain; a session opens a channel once and pays with signed vouchers.
An agent calls a paid API 12 times.
One-time charge
every request settles onchain
0
Onchain txs
0
Off-chain vouchers
Session
open once, pay with vouchers, close
0
Onchain txs
0
Off-chain vouchers
Sessions use payment channels enshrined in T5, which cut channel gas by up to 72%.
How It Works on Tempo
01
Server returns 402
WWW-Authenticate: Payment names the price.
02
Client pays
A signed charge, or a voucher on an open session.
03
Retry with proof
Authorization: Payment → 200 OK with a receipt.
In Practice
RedotPayWhat It Unlocks
01
Agentic checkout
RedotPay agents buy for 7.5M users.
02
Pay-per-call APIs
Price any endpoint without selling keys.
03
Metered AI
Bill streamed output by the token or word.