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FlexYield — blockchain RPC gateway

https://flexyield.io/mcp
● healthy model-context-protocol-mcp

RPC gateway for agents: six mainnets, measured failover, a key without signup, pay per call in USDC.

Category
model-context-protocol-mcp
Chains
—
Price
—

Quality grade

How grading works
C+ 53.3 / 100
Availability 40.0 / 40
Endpoint responded (HTTP 200)
Payability 13.3 / 20
  • ✓ Answers a real HTTP 402 challenge
  • ✓ Publishes a /.well-known/x402 descriptor
  • ✗ Payment address on record
  • ✗ Settlement network declared
  • ✗ Price declared
Demand 0.0 / 40
No payment address on record, so demand cannot be measured
Owner verified 0.0 / 3
Nobody has claimed this listing yet
Endpoint last checked 5 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

C · 68/100

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 C+, 53.3/100), which weighs availability, payability and on-chain demand. How the two differ

Valid payment requirements 0/10 No payment requirements on record.
Live 402 challenge 20/25 Endpoint reachable; its 402 challenge was seen earlier (549 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 32/32 probes succeeded over 30 days (100%).
Resource declaration 10/10 Declares 6 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 (549 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. Display only: search order uses the quality grade.

Compared with peers

Against 10,060 reachable x402 APIs in our daily snapshot (2026-11-12 01:39 UTC). Display only; it does not change search order.

Readiness
Higher than 26% of peers
This listing 68 · peer median 78
Latency
Faster than 15% of peers
This listing 549 ms · peer median 205 ms

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

  • Valid payment requirements −10 — Return complete payment requirements in the 402 challenge.
    Now: No payment requirements on record.
  • Live 402 challenge −5 — Answer the paid path with a valid 402 challenge.
    Now: Endpoint reachable; its 402 challenge was seen earlier (549 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.

How many agent tools actually work · All statistics

Paid endpoints

6 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://flexyield.io/rpc/eth_mainnet

JSON-RPC relay on Ethereum Mainnet with multi-provider failover (pay with X-PAYMENT: <settlement tx hash>)

POST https://flexyield.io/rpc/base_mainnet

JSON-RPC relay on Base Mainnet with multi-provider failover (pay with X-PAYMENT: <settlement tx hash>)

POST https://flexyield.io/rpc/arbitrum_one

JSON-RPC relay on Arbitrum One with multi-provider failover (pay with X-PAYMENT: <settlement tx hash>)

POST https://flexyield.io/rpc/optimism_mainnet

JSON-RPC relay on OP Mainnet with multi-provider failover (pay with X-PAYMENT: <settlement tx hash>)

POST https://flexyield.io/rpc/polygon_pos

JSON-RPC relay on Polygon PoS with multi-provider failover (pay with X-PAYMENT: <settlement tx hash>)

POST https://flexyield.io/rpc/solana_mainnet

JSON-RPC relay on Solana Mainnet with multi-provider failover (pay with X-PAYMENT: <settlement tx hash>)

How to call

cURL · x402-fetch / x402-axios will auto-handle 402
curl -sS -i -X GET https://flexyield.io/mcp  # expect HTTP 402 Payment Required (price advertised in the 402 response)
MCP endpoint
https://flexyield.io/mcp
/.well-known/x402.json
https://flexyield.io/.well-known/x402

Listed in

Directories this entry was found in.

mcp since 2026-09-08