lvlltd.com · Marketplace · Pricing · All listings · First unlock
Coding
Skill id: backend-api-patterns
· Standard
New public or agent-facing API — Backend API Patterns
Product name: Backend API Patterns
$0.099 USDC / unlock · Base · x402
Launch sale — 90% off · was $0.99 · now $0.099 USDC (regular price returns when the sale ends)
Contract-first backend API patterns for human and agent clients: schemas, errors, auth, idempotency, versioning, and 402-aware pay paths where relevant.
Buy with USDC Free outline JSON Free sample x402 challenge
Provenance & integrity
- Publisher
- lvl X, Inc. · lvlltd.com
- Payment
- USDC on Base (eip155:8453) via HTTP 402 · sealed pack after verified tx
- Content class
capability_pack_outline- Sealed data_hash
0x129d5c7681bb34ae691de7b84f5d612237ef04e6517a1cb2ca63385695540ae8- iNFT token_id
16977485829547366548- Trust scorecard
- /api/trust?skill=backend-api-patterns
- Signed provenance
- https://lvlltd.com/provenance/backend-api-patterns.json
- Public ledger
- /api/proof (on-chain unlock rows; currently self-funded test transactions, not customer sales — never estimated)
When to use
- New public or agent-facing API
- Breaking change risk
- x402 endpoints
What you get
- Resources and operations
- Schemas + examples
- Error catalog
- Auth and idempotency
- Versioning
- Consumer tests
Tags: coding, x402, factory:master-2026-07-28, depth:deep, depth:standard
Buyer reviews
Wallet-attested only — no seed ratings. API: /api/reviews?skill=backend-api-patterns
Machine links
- GET /api/pay — 402 challenge
- Trust scorecard JSON
- Related skills JSON
- Reviews JSON
- Free outline.json · sample.md
- Full catalog.json
- llms.txt · llms-full.txt
Sealed capability pack for agents and humans. Free evaluation before pay. Payments: USDC on Base via HTTP 402. Company: lvl X, Inc.