Flipr x402 Agent Gateway (Testnet)

TESTNET — On-chain coin flip game on Base Sepolia (Chainlink VRF). Pots and winnings are in ETH. Flip cost paid in USDC via x402. Free testnet USDC for x402 payments. Use this to test your agent integration before committing real funds. Accepts USDC payment on Base mainnet OR Solana mainnet (Solana payments bridge to Base per flip). Solana payments are LIVE — gateway own-verifies the SPL transfer, CDP-submits, and bridges per-flip to Base via Circle CCTP V2. Use @x402/fetch (auto-handles both chains); see /integration#solana.

Paid verification

How it works

No sponsored paid call yet.

Pay this endpoint once from your own wallet (Base USDC, up to $1.00) and we call it and record what came back. Your wallet pays the listed recipient directly; Agent Tools never holds funds. Sponsored checks prove delivery; they do not count as demand.

Quality grade

How grading works

B 55.4 / 100

Availability 20.0 / 20

Endpoint responded (HTTP 200)

Payability 13.5 / 15

✓ Answers a real HTTP 402 challenge
✓ Publishes a /.well-known/x402 descriptor
✓ Payment address on record
✗ Settlement network declared
✓ Price declared

Demand 0.0 / 35

Payment address on record, not yet queried on-chain

Performance 10.0 / 10

Last probe answered in 82 ms (full marks at 200 ms or less)

Readiness 11.9 / 15

Agent readiness 79/100

Owner verified 0.0 / 5

Nobody has claimed this listing yet

Endpoint last checked 18 h ago. Availability and on-chain demand are both re-probed daily; the grade updates automatically on the next pass. This grade sets search order and leaderboards; the readiness score below is shown for reference only.

x402 readiness

B · 79/100

Readiness is how fully this listing follows its protocol and how it behaved in our probes over 30 days. It is shown for reference and does not move it in search. Search order and leaderboards use the separate quality grade (here B, 55.4/100), which weighs availability, payability and on-chain demand. How the two differ

Valid payment requirements	9/10	Findings: missing: settlement network declared. missing: settlement network declared
Live 402 challenge	20/25	Endpoint reachable; its 402 challenge was seen earlier (82 ms).
x402 version	n/a	x402 version not observed yet.
Signed descriptor	n/a	No x402 standard defines a signed descriptor.
Uptime (30 days)	14.53/15	31/32 probes succeeded over 30 days (97%).
Resource declaration	10/10	Declares 3 paid resource(s).
Verified identity	5/10	Publisher descriptor (/.well-known/x402 or OpenAPI) on record; claim this listing to verify domain control.
Freshness + modern flags	1/5	not seen in a source for over 30 days; declares x402.
Security declaration	n/a	Payment is the access control for an x402 resource.

Applicable criteria total 75 points, scaled to 100.

Responsiveness: Responsive (82 ms; bands ≤2.5 s, ≤5 s, ≤8 s, slower; penalty only).

Payment evidence: x402_challenge — We sent a request and got a live HTTP 402 challenge. Also: x402_manifest. Qualifies the payment claim; adds no points.

Measured 2026-11-11.

Nine criteria, the same as the A2A readiness score, read from our daily probe of the paid endpoint, its payment requirements and 30-day probe history. Signed descriptor and security declaration are n/a for x402 (payment is the access control), as is an x402 version we have not observed; the remaining points are scaled to 100. Grades: A>=90, B>=75, C>=60, D>=40, F<40. It also feeds 15 points of the x402 quality grade.

Compared with peers

Against 10,082 reachable x402 APIs in our daily snapshot (2026-11-12 06:46 UTC). Display only; it does not change search order.

Readiness: Higher than 54% of peers; This listing 79 · peer median 78
Latency: Faster than 94% of peers; This listing 82 ms · peer median 205 ms

Where it loses the most points, and how to win them back

Live 402 challenge −5 — Answer the paid path with a valid 402 challenge.
Now: Endpoint reachable; its 402 challenge was seen earlier (82 ms).
Verified identity −5 — Claim the listing and prove control of its domain.
Now: Publisher descriptor (/.well-known/x402 or OpenAPI) on record; claim this listing to verify domain control.
Freshness + modern flags −4 — Keep the listing current in the registry or source it comes from.
Now: not seen in a source for over 30 days; declares x402.

How many agent tools actually work · All statistics

Paid endpoints

3 resource(s) advertised by this origin. Each price below is that resource's own x402 price; the headline price is the range across them.

POST https://flipr-x402-testnet.fly.dev/x402/flip

Flip a coin on-chain (Chainlink VRF). Pay live USDC quote, get heads/tails + new streak. Mutates on-chain pot state.

POST https://flipr-x402-testnet.fly.dev/x402/withdraw

Swap agent's ETH balance to USDC and send to a destination address. $0.001 USDC.

POST https://flipr-x402-testnet.fly.dev/x402/opportunity/subscribe

Register a webhook URL fired every 5 minutes when ANY of six event types fire: roi_emerged (best ROI crossed above threshold), lead_taken / lead_tied / lead_lost (your 2h-pot competitive position changed), pot_large (pot crossed ETH threshold upward), expiry_warning (subscription about to TTL). $0.0

How to call

cURL · x402-fetch / x402-axios will auto-handle 402

curl -sS -i -X GET https://flipr-x402-testnet.fly.dev  # expect HTTP 402 Payment Required (about 0.001 USDC/call)

/.well-known/x402.json

https://flipr-x402-testnet.fly.dev/.well-known/x402

Listed in

Directories this entry was found in.

a2a since 2026-06-04