Unknown costs at request time
Agent workflows are variable. You can't price a multi-step run upfront.
Payments are the last step. The hard part is everything before: credits, prepaid plans, refunds, usage caps, and line-item audit trails.
Processing 10K+ API calls daily
x402 is a payment signal,The moment you meter real workloads, payment alone breaks down. You need authorization ceilings, credits, refunds, and a ledger that reconciles every token.
Agent workflows are variable. You can't price a multi-step run upfront.
Pay-then-serve forces users to prepay and hope. That kills trust.
Without line-item accounting, you can't know what each run cost or earned.
x402 viableWe sit in front of your agent traffic as a proxy. We meter the full workflow, compute the ledger, and settle the exact amount—whether prepaid, postpaid, or credit-based.
Finally answer: "What's the P&L of each agent run?"
Set a max, stream usage, capture only what was consumed.
Package usage into credits with discounts and flexible terms.
Every tool call becomes a debit and credit. Margin is visible.
Guardrail spend with per-user, per-agent, per-org limits.
Failed runs reversed cleanly with full audit trail.
Unified cost basis across all providers and tools.
Run a credit-style model on top of x402. Agents transact independently within limits set by human or org owners.
Micro
$0.001
Single tool call
Macro
$1,000
High-value workflow
Same accounting backbone handles both—no prefunded wallet required.
Agent maps to KYC'd owner with set limits
SDK detects challenge, requests authorization
StringCost draws from pool, opens ledger
Pay in stablecoins while usage accrues
Close run, refund delta automatically
x402 without StringCostPayment protocols don't replace accounting. Here's what you're missing.
x402 signals payment required. StringCost turns that into a session that prices variable workloads in real time.
Gateway replies with a payment-required challenge if no active session exists.
We create an authorization ceiling, issue a signed session, start a ledger.
Each token, tool call, compute step becomes a line item with cost and revenue.
Capture exact amount used, return the remainder, close the books.
Proxy accounting, credits, and settlements in one stack. Built for usage-based AI.