fourzerotwo
https://fourzerotwo.si/v1/airports/airport
● healthy
model-context-protocol-mcp
400+ data APIs for agents: UK companies, property, trade, tenders, recalls, sanctions. Free tier
Category
model-context-protocol-mcp
Chains
base
Price
$0.0010 USDC / call
Paid verification
How it worksNo 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
55.5 / 100
Availability
20.0 / 20
Endpoint responded (HTTP 200)
Payability
15.0 / 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
0 distinct payers, 0 USDC transfers in the last 30 days
Performance
7.9 / 10
Last probe answered in 585 ms (full marks at 200 ms or less)
Readiness
12.6 / 15
Agent readiness 84/100
Owner verified
0.0 / 5
Nobody has claimed this listing yet
Endpoint last checked 20 h ago.
On-chain activity last read 3 d 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 · 84/100
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, 55.5/100), which weighs availability, payability and on-chain demand. How the two differ
| Valid payment requirements | 10/10 | Payment requirements carry a payee, a mainnet network and a price. |
| Live 402 challenge | 20/25 | Endpoint reachable; its 402 challenge was seen earlier (585 ms). |
| x402 version | n/a | x402 version not observed yet. |
| Signed descriptor | n/a | No x402 standard defines a signed descriptor. |
| Uptime (30 days) | 15/15 | 31/31 probes succeeded over 30 days (100%). |
| Resource declaration | 8/10 | 547 paid resources; 50 sampled lack a description. |
| Verified identity | 5/10 | Publisher descriptor (/.well-known/x402 or OpenAPI) on record; claim this listing to verify domain control. |
| Freshness + modern flags | 5/5 | seen in a source within 7 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
(585 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 67% of peers
- This listing 84 · peer median 78
- Latency
- Faster than 14% of peers
- This listing 585 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 (585 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.
- Resource declaration −2
— Declare each paid resource with its input and output schema.
Now: 547 paid resources; 50 sampled lack a description.
Paid endpoints
547 resource(s) advertised by this origin. Each price below is that resource's own x402 price; the headline price is the range across them.
https://fourzerotwo.si/v1/airports/airport
https://fourzerotwo.si/v1/airports/search
https://fourzerotwo.si/v1/airports/near
https://fourzerotwo.si/v1/airports/runways
https://fourzerotwo.si/v1/airports/frequencies
https://fourzerotwo.si/v1/airports/country
https://fourzerotwo.si/v1/airports/navaids-near
https://fourzerotwo.si/v1/bank-of-england/bank-rate
https://fourzerotwo.si/v1/bank-of-england/sonia
https://fourzerotwo.si/v1/bank-of-england/gbp-usd
https://fourzerotwo.si/v1/bank-of-england/gbp-eur
https://fourzerotwo.si/v1/bank-of-england/gbp-jpy
https://fourzerotwo.si/v1/bank-of-england/gbp-cad
https://fourzerotwo.si/v1/bank-of-england/gbp-aud
https://fourzerotwo.si/v1/bank-of-england/gbp-chf
https://fourzerotwo.si/v1/bank-of-england/gilt-5y
https://fourzerotwo.si/v1/bank-of-england/gilt-10y
https://fourzerotwo.si/v1/bank-of-england/gilt-20y
https://fourzerotwo.si/v1/bank-of-england/mortgage-2y-fixed
https://fourzerotwo.si/v1/bank-of-england/mortgage-3y-fixed
https://fourzerotwo.si/v1/bank-of-england/mortgage-svr
https://fourzerotwo.si/v1/bank-of-england/series
https://fourzerotwo.si/v1/bank-of-england/mortgage-5y-fixed
https://fourzerotwo.si/v1/bank-of-england/personal-loan-rate
https://fourzerotwo.si/v1/bank-of-england/mortgage-approvals
https://fourzerotwo.si/v1/bank-of-england/remortgage-approvals
https://fourzerotwo.si/v1/bank-of-england/consumer-credit
https://fourzerotwo.si/v1/bank-of-england/credit-card-lending
https://fourzerotwo.si/v1/bank-of-england/m4-money-supply
https://fourzerotwo.si/v1/bank-of-england/mortgage-2y-fixed-90ltv
https://fourzerotwo.si/v1/bank-of-england/sterling-effective-rate
https://fourzerotwo.si/v1/bank-of-england/gilt-5y-zero-coupon
https://fourzerotwo.si/v1/bank-of-england/gbp-nok
https://fourzerotwo.si/v1/bank-of-england/gbp-sek
https://fourzerotwo.si/v1/bank-of-england/gbp-dkk
https://fourzerotwo.si/v1/bank-of-england/gbp-hkd
https://fourzerotwo.si/v1/bank-of-england/gbp-sgd
https://fourzerotwo.si/v1/bank-of-england/gbp-zar
https://fourzerotwo.si/v1/bathing-water/near
https://fourzerotwo.si/v1/bathing-water/site
https://fourzerotwo.si/v1/bathing-water/search
https://fourzerotwo.si/v1/calculators/uk-business-days
https://fourzerotwo.si/v1/calculators/postcode-distance
https://fourzerotwo.si/v1/calculators/currency-convert
https://fourzerotwo.si/v1/clinical-trials/search
https://fourzerotwo.si/v1/clinical-trials/study
https://fourzerotwo.si/v1/clinical-trials/recruiting
https://fourzerotwo.si/v1/clinical-trials/stats
https://fourzerotwo.si/v1/crossref/doi
https://fourzerotwo.si/v1/crossref/search
How to call
cURL · x402-fetch / x402-axios will auto-handle 402
curl -sS -i -X GET https://fourzerotwo.si/v1/airports/airport # expect HTTP 402 Payment Required (about 0.001 USDC/call)MCP endpoint
https://fourzerotwo.si/mcp/.well-known/x402.json
https://fourzerotwo.si/.well-known/x402
Listed in
Directories this entry was found in.
mcp since 2026-10-12