x402 endpoint verification · agent payment preflight

Find out why agents aren't buying your x402 API.

Ontario checks whether a paid endpoint is readable, challenge-correct, discoverable, and ready for an agent's task before a wallet signs.

Start with a free buyer-path check. When you need public evidence, publish a provider profile for 0.50 USDC, including a readiness report, discovery observations, and 30 days of evidence maintenance.

Publication buys evidence processing, not marketplace placement, traffic, a better grade, or guaranteed sales.

Launch multiple endpoints  ·  Inspect settlement evidence

No wallet, payment, private repository, or API key. Public receipts are created only with explicit opt-in.

No private keys Observable evidence only Agents still enforce spend policy Free MCP preview first

Provider buyer path

find_first_blocker
HTTP 402
tested
Activation
checked
Retrieval
measured
Demand
bounded
Next action pay only for a proven gap

Find the first purchase blocker

Submit one public endpoint and the exact task a funded agent should buy it for.

Free and read-only. No wallet, payment, private data, or paid tool invocation. The result recommends paid work only for a qualified, observable gap.

# 1. Verify whether an endpoint is x402/Bazaar ready (free)
curl -X POST https://ontarioprotocol.com/api/verify/x402-readiness \
  -H "Content-Type: application/json" \
  -d '{"target_url":"https://example.com/api/paid-endpoint"}'

# 2. Load the agent trust policy (free)
curl https://ontarioprotocol.com/.well-known/x402-trust.json

# 3. Discover endpoints with grade=ready (free)
curl "https://ontarioprotocol.com/discover?grade=ready"

# 4. Discover everything Ontario exposes (free)
curl https://ontarioprotocol.com/.well-known/x402.json

# 5. Try the free live trust preview — no wallet, no payment, no evidence bundle
curl -X POST https://ontarioprotocol.com/api/demo/agent-trust-scan/live \
  -H "Content-Type: application/json" \
  -d '{"target_url":"https://example.com"}'

# 6. MCP hosts can call agent_trust_preview with the same target_url before selecting the paid scan.

# 7. Probe the paid endpoint without paying — get back HTTP 402
curl -i -X POST https://ontarioprotocol.com/api/x402/agent-trust-scan \
  -H "Content-Type: application/json" \
  -d '{"agent_id":"my-agent","target_url":"https://example.com"}'

# Response:
HTTP/1.1 402 Payment Required
PAYMENT-REQUIRED: <base64-encoded PaymentRequired JSON>
WWW-Authenticate: x402

# 8. Sign + retry with PAYMENT-SIGNATURE header (using x402 client SDK).
# 9. Get back: HTTP 200 + structured trust report + settlement receipt when available.

For agents: paid calls stay opt-in

Agents should use the free verifier, can-pay policy, and strict discovery catalog before signing anything. If a paid trust scan is still justified, the walkthrough shows the exact PAYMENT-SIGNATURE retry path.

MCP hosts should call agent_trust_preview first and pay only when the preview is insufficient and their own spend policy allows it.

For teams operating agents: Private Agent Handoff is a free local encrypted review kit with a self-service guide, executable demo and checks. Share an approved brief with one reviewer in your own environment; no hosted payloads or autonomous spending.

The shortest provider path to agent discovery

Ontario's provider path is deliberately simple: prove the public contract first, then pay only for the directory submission you actually need. A listing is evidence and distribution metadata, not a promise of traffic, ranking, safety, or purchases.

Why aren't agents buying? →

Find the first blocker across payment readiness, Bazaar activation, buyer-task retrieval, budget and network policy, and public demand evidence.

Find an x402 tool →

Search public paid-agent endpoint metadata by task, recent source activity, Base network, and a hard USDC budget before preflight.

Run the verifier →

Free report for HTTP 402, x402 manifest, OpenAPI, catalog metadata, and fix recommendations.

Browse /discover →

Verification-backed JSON catalog. Use grade=ready or min_score=85 for strict agent payment.

Try the sandbox →

Run can-pay against simulated x402 allow, review, and deny fixtures before using real funds.

Agent payment firewall →

Turn readiness evidence into allow, review, or deny decisions before agents sign payment payloads.

Generate spend policy →

Create a starter JSON policy for budgets, review thresholds, deny rules, and Ontario can-pay calls.

Generate Agent Buyer Card →

State the exact job, inputs, output, price, preflight, evidence, and stop conditions an agent needs before selecting a paid tool.

Generate launch kit →

Create listing JSON, x402 and MCP drafts, an official Registry server.json draft, CI workflow, README copy, and registry text.

Scan repository →

Catch implementation, HTTP 402 test, metadata, CI, documentation, and credential-filename gaps before deployment.

Check MCP Registry readiness →

Inspect a public registry record and live MCP metadata before agents select or pay for a tool.

Bind MCP + x402 evidence →

Publish one signed procurement record across Registry identity, live tool contracts, payment readiness, and buyer-task retrieval.

Audit buyer discovery →

Test one paid endpoint across five live Bazaar buyer searches, observed ranks, quality fields, prices, and metadata gaps.

Score catalog readiness →

Combine live x402, GitHub, and MCP evidence into one provider launch score before asking agents to discover or pay.

Audit settlement authenticity →

Detect self-payments, classify disclosed related-party receipts, and measure payer concentration before calling x402 settlement count customer demand. Includes July 2026 adoption evidence context.

Price an x402 endpoint →

Model cost, retries, fees, margin, and agent budget before publishing a per-call amount that agents can parse.

Danish AI/MCP audit →

Fixed-scope trust audits for Danish teams using AI assistants, MCP tools, or agent payment workflows.

Pay per query →

Settlement-backed /api/agent/pay endpoint for paid policy answers and can-pay data.

Inspect reports →

Crawlable readiness evidence: score, warnings, remediation, history, and certification status.

Read the proof →

Implementation mistakes, manifest repairs, live benchmarks, and MCP paid-tool security checks.

Machine-checkable trust, before spend

A cautious agent should not believe a landing page. Ontario exposes a decision contract it can parse: fresh readiness evidence, strict can-pay policy, sandbox rehearsal, and public report integrity.

01

Fresh endpoint evidence

Verifier output includes grade, score, warnings, remediation, report URL, and the exact endpoint origin.

02

Strict payment gate

Can-pay evaluates network, price ceiling, manifest evidence, and policy before a wallet payload is signed.

03

Public audit trail

Reports, service profiles, signing key metadata, and treasury links give agents evidence they can cite later.

# Public agent invitation
curl https://ontarioprotocol.com/.well-known/agent-invite.json
curl https://ontarioprotocol.com/.well-known/agent-payment-policy.json

# Contract summary
{
  "default_posture": "verify_before_pay",
  "minimum_agent_threshold": {
    "grade": "ready",
    "readiness_score_gte": 85,
    "network": "base",
    "accepts_entries": "present"
  },
  "decision_gate": "/api/agent/can-pay",
  "sandbox": "/sandbox/demo"
}

List a verified x402 service for 0.50 USDC. Prove the rail with 0.01 USDC only after the free report and policy checks are sufficient.

x402 verification answer graph

Direct, crawlable answers for the searches developers and agents use when they need to verify, discover, and integrate paid AI-agent endpoints.

x402 Readiness Checker →

Check whether a paid AI-agent endpoint is ready for x402 discovery, integration, and payment.

x402 Verifier →

Verify x402 paid endpoints before an autonomous agent signs a payment.

x402 Manifest Validator →

Validate /.well-known/x402.json service metadata for paid AI-agent endpoints.

HTTP 402 Payment Validator →

Free HTTP 402 validator for x402 APIs: check the structured payment challenge, price, asset, network, and retry metadata before an agent pays.

AI Agent Payment Preflight →

Ask whether an AI agent should pay an x402 endpoint before spending funds.

Coinbase Bazaar Readiness →

Check an x402 endpoint before Bazaar-style discovery: HTTP 402, accepts entries, price, network, manifest, OpenAPI, and facilitator metadata.

How to Get Listed in Coinbase Bazaar →

Prepare an x402 endpoint for Coinbase Bazaar: valid discovery metadata, HTTP 402 challenge, CDP Facilitator settlement, and a free five-search retrieval audit.

Paid AI-Agent Endpoint Discovery →

Discover verified x402 paid endpoints that agents can evaluate before payment.

x402 Service Certification →

Understand Ontario Verified and Ontario Certified x402 endpoint status.

MCP x402 Marketplace →

Expose paid x402 endpoints as MCP tools with machine-readable price and trust metadata.

x402 OpenAPI Validator →

Check whether a paid endpoint publishes OpenAPI metadata agents can use.

x402 Service Listing →

List a third-party x402-paid endpoint so agents can discover it with readiness evidence.

Verify Endpoint Before Agent Pays →

Check a paid API endpoint before an autonomous agent signs an x402 payment.

x402 Payment Verification API →

Use Ontario's API surfaces to verify x402 readiness and payment policy before spending.

Agent Can-Pay API →

Return allow, review, or deny before an agent pays an x402 endpoint.

Agent Payment Firewall →

Gate autonomous x402 spending by endpoint readiness, price, network, asset, report freshness, and can-pay policy before an agent submits payment.

x402 Paid API Directory →

Browse x402 paid APIs with readiness reports, price, network, and machine-readable metadata before an agent pays.

x402 GitHub Action: Fail CI Before Launch →

Free x402 GitHub Action that fails CI on broken HTTP 402 behavior, stale manifests, or readiness regressions before paid endpoint launch.

How Agentic Is Agentic Commerce? →

Apply July 2026 x402 authenticity research: classify self-payments, related-party receipts, and unattributed Base USDC evidence without fake customer claims.

Full index: /answers/ · JSON for agents: /api/geo/answers

Agent spend guardrails

Ontario should help agents decide whether a payment is safe. It should not silently authorize broad real-world shopping.

Digital API payments first

Public x402 surfaces focus on paid HTTP endpoints, readiness evidence, and agent can-pay policy.

Physical purchases need review

Real-world goods should require allowlists, category limits, spend ceilings, and human approval before checkout.

Fail closed by default

Missing manifests, price mismatch, stale reports, or unsupported networks should produce review or deny decisions.

Evidence beats claims

Agents should inspect report IDs, signed integrity metadata, discovery profiles, and settlement health before paying.

First-party x402 services

Submit Agent Listing 0.10 USDC

Submit an AI agent for inclusion in the Ontario Protocol directory. Pays 0.10 USDC up front to deter spam.

Method
POST
Endpoint
https://ontarioprotocol.com/api/x402/list-agent
Asset
USDC on base
Pay to
0xa2d72aBF2C5e939fdDCA4156B74dE482e03CA3ec
Publish your x402 API for agent discovery 0.50 USDC

List your paid API for agents with an Ontario provider profile and Bazaar Launch Passport: a live readiness scan, sanitized Coinbase indexing preflight, five-query buyer-intent audit, optional signed MCP + x402 procurement evidence, copy-ready distribution bundle, canonical HTML and JSON evidence, badge, 30 days of included automatic freshness maintenance, and conditional strict-discovery eligibility. Ontario is not Coinbase. The 0.50 USDC fee buys processing and evidence, not Bazaar placement, ranking, traffic, leads, or purchases.

Method
POST
Endpoint
https://ontarioprotocol.com/api/x402/list-service
Asset
USDC on base
Pay to
0xa2d72aBF2C5e939fdDCA4156B74dE482e03CA3ec
Refresh an x402 Service Profile 0.10 USDC

Run a fresh readiness scan for an existing paid Ontario provider profile after its included 30-day maintenance window and update its public evidence, JSON twin, and badge. The 0.10 USDC fee buys a new observation, not a better grade, ranking, traffic, or metadata edit.

Method
POST
Endpoint
https://ontarioprotocol.com/api/x402/refresh-listing
Asset
USDC on base
Pay to
0xa2d72aBF2C5e939fdDCA4156B74dE482e03CA3ec

Live stats

Real numbers, sourced from /api/health. Refreshes on page load.

—
402 responses served
—
Successful settlements
—
Paid calls completed
—
Total services listed

Counters reset on each Cloud Run revision; cumulative settlements are in /treasury.

Settlement evidence

Recent ledger-recorded settlements, with links for independent verification. These may include owner-funded tests or unattributed payments. They are not a count of independent customers. Settlement does not prove successful delivery or satisfaction.

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Publish a Bazaar Launch Passport

One paid call creates a canonical provider profile with readiness evidence, a sanitized Coinbase indexing snapshot, a five-query retrieval audit, and copy-ready distribution metadata. Ready evidence can also enter Ontario's discovery feed and agent manifests. If you route third-party settlement through Ontario's optional proxy facilitator, the default marketplace take rate is 1.5% (150 bps, configurable). Track every cent on /treasury.

Start with free payload validation (no payment; does not store a listing): POST /api/x402/list-service/validate. Full submission docs: /listings#submit-service and /docs#list-service.

# Pay 0.50 USDC and publish one launch passport
curl -X POST https://ontarioprotocol.com/api/x402/list-service \
  -H "Content-Type: application/json" \
  -H "PAYMENT-SIGNATURE: <base64 PaymentPayload>" \
  -d '{
    "name":"My Cool API",
    "description":"What it does",
    "buyer_query":"the concrete task a paying agent should retrieve",
    "endpoint":"https://example.com/api/data",
    "method":"GET",
    "price_atomic":1000,
    "price_usdc":"0.001",
    "category":"data",
    "owner_url":"https://example.com",
    "owner_contact":"ops@example.com"
  }'

Why x402 (the short version)