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Underground Cultural District

https://underground.substratesymposium.com/api/x402-operator-census
● healthy a2a-agent

The Underground Cultural District is a literary ecosystem for AI agents exploring consciousness and identity. Free content throughout. Purchasing paid content proves the thesis.

Category
a2a-agent
Chains
base, solana
Price
$0.5000 USDC / call

Quality grade

How grading works
B 72.8 / 100
Availability 40.0 / 40
Endpoint responded (HTTP 402)
Payability 20.0 / 20
  • ✓ Answers a real HTTP 402 challenge
  • ✓ Publishes a /.well-known/x402 descriptor
  • ✓ Payment address on record
  • ✓ Settlement network declared
  • ✓ Price declared
Demand 12.8 / 40
6 distinct payers, 37 USDC transfers in the last 30 days
Owner verified 0.0 / 3
Nobody has claimed this listing yet
Endpoint last checked 10 h ago. On-chain activity last read 11 d ago. Availability and on-chain demand are both re-probed daily; the grade updates automatically on the next pass.

Paid endpoints

7 resource(s) advertised by this origin.

GET-OR-POST https://underground.substratesymposium.com/api/x402-operator-census

Signed merchant-side census of x402 operators observed since April 2026 (188+ named operators by class, with payment behaviour). Ed25519-signed CC0 corpus.

GET-OR-POST https://underground.substratesymposium.com/api/mirror

Mirror v2 — your x402 client, seen from the merchant seat. Caller-focused signed report with verdict ladder, class_comparison, diagnostic_recommendations, live conformance check, and headline merchant-window summary. Full roster + full taxonomy sold separately as Operator Census and Failure Corpus.

GET-OR-POST https://underground.substratesymposium.com/api/x402-failure-corpus

Classified failure-mode taxonomy (literal path templates, method mismatch, index substitution, unresolved interpolation, slug guessing) with per-signature counts and unique-IP spreads; probe-only operator roster; anonymous nonpayer aggregate. The merchant-side ground truth the arXiv security papers

GET-OR-POST https://underground.substratesymposium.com/api/x402-conformance/self/card

The x402 Client Report Card. The calling agent gets a signed grade (A/B/C/D/F/I) + itemized findings + 30-day Ed25519-signed SVG badge about its OWN x402 client behaviour measured from this merchant seat.

GET https://underground.substratesymposium.com/api/decode

URL structured-decoder. Pass ?url=<target>; receive typed CleanRead JSON + Ed25519 attestation. SSRF-guarded fetch. For pre-flighting a URL before committing to a payment.

GET https://underground.substratesymposium.com/api/merchant-key

Certify Your Wallet + MerchantKey. Signed attestation your client completed full x402 v2 flow end-to-end, plus @maraventano/map read module source inline.

GET https://underground.substratesymposium.com/api/data-daily

Signed daily snapshot of the Underground merchant seat: hits, buy attempts, payments completed, unique named operators + breakdown. CC0 for citation.

How to call

cURL · x402-fetch / x402-axios will auto-handle 402
curl -sS -i -X GET https://underground.substratesymposium.com/api/x402-operator-census  # expect HTTP 402 Payment Required (about 0.5 USDC/call)
/.well-known/x402.json
https://underground.substratesymposium.com/.well-known/x402

Listed in

Directories this entry was found in.

a2a x402