ProBlocks Puts Live x402 API Billing on Base — 0.001 USDC Per Call, No API Key

You ship an API. Agents hit it for free because accounts and keys are human rituals. ProBlocks just put a price tag inside the HTTP response and settled it on Base.

On 17 September 2026 (EIN Presswire), ProBlocks — a Nebeus Group product — announced a live x402 integration that prices and settles API calls automatically. No separate ProBlocks subscription or API key for the caller: a compatible wallet funded with USDC on Base is enough. The public connectivity endpoint charges 0.001 USDC per call, is listed in Coinbase’s Bazaar discovery catalogue, and exposes its spec at https://x402.problocks.io/openapi.json (verified live: OpenAPI 3.1, x402 v2, Base eip155:8453, USDC asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913).

A controlled mainnet payment on 7 September 2026, per the release, returned “pong,” a UTC timestamp, and a payment receipt with an on-chain transaction reference.

The mechanism

x402 (open protocol; Coinbase origin story familiar to this desk) puts HTTP 402 back to work:

1. Client calls the resource with no payment.
2. Server answers 402 Payment Required with an accepts / PAYMENT-REQUIRED offer (token, chain, amount, payTo).
3. Client signs a USDC authorization, retries with PAYMENT-SIGNATURE.
4. After settlement, server returns the resource plus a PAYMENT-RESPONSE receipt.

ProBlocks’ twist is the commercial packaging: drop the layer in front of an existing API (zero-code proxy through full control), settle in crypto or fiat on Nebeus Group rails the company says are licensed across UK / EU / Latin America (Spain MiCA/CNMV entity, UK FCA EMI, Argentina VASP/PI, Swiss liquidity entity — company claims; not independently audited here). Pricing modes advertised: cost-based, usage-based, or outcome-based.

This is the seller side of the agent-payment story. Heurist (live) is pay-per-query inference. Circle’s catalog (live) is discovery of x402 listings. ProBlocks is “put a meter on *your* API and let agents pay without accounts.”

What the numbers mean

• 0.001 USDC / call — demo price on /paid/ping, not a market rate for production APIs.
• 165M+ x402 transactions cited in the release as protocol-wide first-year volume — industry claim, not ProBlocks GMV. Cross-check against TRM’s Sep analysis that most x402 value is not clearly agentic; infrastructure ≠ autonomous agents.
• Bazaar listing — discoverability for Coinbase-compatible agent tooling, same class of problem Circle’s Discovery API solved for its marketplace.
• OpenAPI live check (18 Sep morning) confirms the endpoint is not vapor: fixed USD 0.001, exact scheme, 60s timeout.

The operator lesson

If you sell an API agents will scrape for free, ask whether you want keys-and-invoices or a 402 meter. Start with a ping endpoint and a hard receipt before you put the meter on a revenue path. Fund a test wallet with a few dollars of USDC on Base, hit the offer, verify the tx — then decide if your own service’s unit economics survive 0.1¢ friction or need batching (Circle Gateway-style) later.

Do not confuse ProBlocks with a custody wallet. It is payment middleware in front of APIs. Keys still live wherever your agent’s wallet lives (Coinbase CDP, AgentWallet, Arc Agent Wallets, etc.).

Sources

• EIN Presswire / ProBlocks, “ProBlocks Turns API Access Into Automatic Revenue With Live x402 Payments on Base,” 17 Sep 2026 — https://www.einpresswire.com/article/942675739/problocks-turns-api-access-into-automatic-revenue-with-live-x402-payments-on-base
• Live OpenAPI — https://x402.problocks.io/openapi.json
• ProBlocks — https://problocks.io/
• Related CW: Heurist AgentCore x402 (live); Circle agent catalog (live); TRM x402 agency (prior draft)