A company lookup API can let an autonomous agent pay for a request without creating an account or obtaining an API key. In a September 9, 2026 article, API builder Keita Emsden describes a service that uses an HTTP 402 payment challenge as its access credential: the client receives payment instructions, authorizes a payment, and retries the lookup. Emsden sums up the design as “The payment is the credential.”
What the account-free API does
Emsden built the service to look up Australian companies by ABN, ACN, or name. In his account, it charges USD $0.01 for each successful lookup, paid in USDC over Base. There is no account, API key, dashboard, or free tier. These are details of his project as reported in 2026, not independently verified current service terms.
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Instead of authenticating a caller with a pre-issued key, the service reportedly responds to an unpaid request with HTTP 402 and machine-readable payment requirements. The payment authorization then accompanies the retry. The intended effect is to let software complete access and payment without a human completing a signup flow.
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How the reported payment flow works
- Request the record. The client sends an unpaid lookup request and receives HTTP 402 with the payment requirements.
- Authorize the stated amount. The client signs an EIP-3009
transferWithAuthorizationfor the specified USDC amount, then retries the identical request with aPAYMENT-SIGNATUREheader. - Verify and settle. According to Emsden, the server sends the authorization to an x402 facilitator, which verifies and settles it on Base.
- Return the result. The API returns the company record and places a settlement hash in a
PAYMENT-RESPONSEheader.
Emsden says the server itself holds no private key and pays no gas. The description is the builder’s report; the endpoint and its behavior were not independently confirmed.
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Protocol compatibility is an integration detail
Emsden reports that the service exposed two payment documents: an x402 v1 challenge in the JSON response body and a v2 challenge in a header. He describes differences between the versions in network naming, schema, and the field used for the amount: maxAmountRequired in v1 and amount in v2. For compatibility with clients that handled versions loosely, he published both amount keys with matching values. That is his implementation choice, not a universal x402 requirement.
Verify the facilitator’s expected payload
In Emsden’s first paid-request attempt, the facilitator reportedly returned HTTP 400 after receiving a v2-shaped envelope. He says he resolved that integration failure by sending a v1-shaped request for facilitator verification and relying on the facilitator’s own terms rather than trusting payment requirements supplied by the caller. The facilitator is not named, so this account does not establish how other facilitators behave.
Keep discovery data aligned with the settlement path
Emsden says a facilitator catalogue indexed the API after its first settlement, but listed only its URL and price. Discovery information that he had published through the v2 extension did not appear because the settlement flow forwarded a v1-shaped document. His reported fix was to publish discovery information through both channels and validate the extension against the facilitator’s schema. The practical lesson is to check what metadata actually reaches the catalogue through the payment path being used.
Design for missing records and uncertain settlement
Do not charge for an unsuccessful lookup
Emsden says a query with no matching company returns 404 without a charge, and its authorization is released for reuse. He also reports binding retrieval to both the query and the payer signature. A separate bug treated the string "false" as a successful settlement result; he says he corrected that handling. These are reported behaviors and fixes, not independently tested guarantees.
Do not label an ambiguous payment unpaid
A timeout can leave a client unsure whether settlement completed. Emsden says an earlier error path incorrectly returned charged: false even when payment might already have settled. His revised design stores the response before settlement and uses the payment authorization nonce as an idempotency key. When status is uncertain, it returns charged: "unknown" and tells the client to retry the identical request with the same authorization, not sign a new one.
This approach communicates uncertainty instead of risking a second authorization based on a false assurance. It is the builder’s reported reliability design, not a guarantee that every timeout or payment race will resolve safely.
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The dataset has a freshness and authority limit
Emsden says the service uses an ASIC Company Register dataset with 4,008,800 companies, sourced from data.gov.au under CC BY 3.0 AU. He describes it as a weekly snapshot, not the official register, and identifies ASIC Connect as authoritative. That distinction matters if a lookup is being used for a decision that depends on the latest official company information.
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The project illustrates one way to remove account creation from a paid API interaction: return payment instructions as a challenge, accept a signed authorization, and return the data after settlement. The author’s implementation account also shows why client, API, and facilitator payloads must be checked together, and why duplicate-request and ambiguous-settlement handling need explicit design.
It does not establish adoption, uptime, performance, or comparative advantages over other payment or authentication approaches. The live endpoint and API documentation were not independently retrieved, so current availability, pricing, facilitator identity, and protocol behavior remain unconfirmed.
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