x402-gated premium API access on Base, pay $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" behind an x402 paywall on the Base network. The specific resource `/api/v1/cards/99` is one of many endpoints offered by the provider, which spans categories including data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. All endpoints share a uniform pricing model of $0.02 per request, settled in USDC (USD Coin) on Base.
The x402 challenge confirms the endpoint is live and accepts POST requests. Payment is made via the x402 exact scheme to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using USDC (`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) on Base. The `maxAmountRequired` is 20000 base units, which at 6 decimals equals $0.02. The provider advertises no API keys, no rate limits, and instant access.
However, the specific functionality of `/api/v1/cards/99` is unclear. The provider's landing page lists many endpoints across different domains but does not include a `/cards/` route in its public catalog. There is no OpenAPI schema, no detailed documentation (the docs, pricing, and README pages all render only a "Connect wallet" prompt), and no example request/response payloads available. The actual data returned by this endpoint is unknown — it could be a card-related resource (e.g., payment cards, trading cards, or informational cards) but this is speculative.
Capabilities
Use cases
- —Programmatic access to a premium data resource with per-request USDC micropayments
- —Agent-driven API consumption without pre-registration or API keys
- —Integrating x402-compatible payment flows into automated workflows
Fit
Best for
- —Developers experimenting with x402 payment protocol on Base
- —Agents needing keyless, pay-per-use API access
- —Low-volume consumers who want no subscription commitments
Not for
- —Users who need detailed documentation or OpenAPI specs before integrating
- —High-volume use cases where per-request pricing may add up without bulk discounts
- —Anyone needing to understand the exact response schema before paying
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/cards/99 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, the specific purpose of /api/v1/cards/99 is undocumented, there is no OpenAPI schema, no example requests or responses, and the docs/pricing/README pages are all empty beyond a wallet connect prompt. The actual functionality is unknown.
Warnings
- —The /api/v1/cards/99 path is not listed in the provider's public API catalog — its purpose is unclear.
- —No OpenAPI schema or documentation is available for this endpoint.
- —All documentation pages (docs, pricing, README) render only a 'Connect wallet' prompt with no actual content.
- —Response format and fields are completely unknown — no example responses available.
Citations
- —The x402 challenge returns maxAmountRequired of 20000 base units in USDC on Base networkhttps://lowpaymentfee.com/api/v1/cards/99
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/cards/99
- —Provider advertises $0.02 per request, no API keys, no rate limits, instant accesshttps://lowpaymentfee.com
- —Provider lists endpoints across data & analytics, AI & ML, finance & Web3, and infrastructure categorieshttps://lowpaymentfee.com