x402basequality 0.78

Pay-per-use GPT endpoint on Base via x402 — no API keys, just USDC micropayments.

Price
0.01 USDC / call
Protocol
x402
Verified
no
Endpoint
https://x402factory.ai/base/llm/gpt

What it does

x402Factory's GPT endpoint exposes OpenAI GPT models (gpt-5.1, gpt-5-mini, gpt-5-nano, gpt-5-pro) behind an x402 payment wall on the Base network. Callers pay in USDC per request with no accounts or API keys required — the payment itself serves as authentication. The default call uses gpt-5-mini with up to 1000 input tokens and 2000 max output tokens for a fixed price of 0.01 USDC. For non-default configurations, pricing is computed as (input_tokens × input_price_per_million + max_output_tokens × output_price_per_million) / 1,000,000, with a minimum of 0.001 USDC, always rounded up to 6 decimals.

Beyond simple message calls, the endpoint supports three actions: `message` (or omit action) for a direct GPT completion, `create` to store a custom agent with a preprompt for 0.001 USDC, and `list` to retrieve up to 100 recent custom agents for the paying wallet for 0.001 USDC. Custom agents are reusable — once created, they can be invoked via `custom_id` in the request body or as a URL path parameter (`/base/llm/gpt/{custom_id}`), each call priced based on the agent's stored preprompt, model, max_output_tokens, and max_input_tokens.

The endpoint returns a well-defined JSON schema including fields like `ok`, `action`, `model`, `price_usdc`, `reply`, and `custom_id`. An optional `max_input_tokens` parameter lets callers cap input token pricing; if the actual message exceeds this cap, the server returns an error rather than under-pricing. The x402 challenge is live on Base (chain ID 8453) and payments settle to address 0x402FaCcC3fAeb72351CC2b68C7966faF5f22B0d4 using the USDC contract at 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913.

Capabilities

llm-completiongpt-5-minigpt-5.1gpt-5-nanogpt-5-procustom-agent-creationcustom-agent-listingx402-paymentusdc-micropaymentbase-networkper-request-pricingno-api-key

Use cases

  • —AI agents that need on-demand GPT completions without managing API keys
  • —Creating reusable custom agents with stored system prompts for repeated tasks
  • —Prototyping LLM-powered workflows with instant USDC micropayments on Base
  • —Autonomous agents discovering and consuming LLM endpoints via x402 protocol
  • —Building chatbot backends where each query is individually metered and paid

Fit

Best for

  • —Autonomous AI agents needing keyless, pay-per-call GPT access
  • —Developers who want to avoid OpenAI account management and billing complexity
  • —Micropayment-based LLM consumption on Base/USDC
  • —Creating persistent custom agents with fixed preprompts for repeated use

Not for

  • —High-volume production workloads where OpenAI direct billing is cheaper
  • —Use cases requiring streaming responses (no streaming mentioned in schema)
  • —Applications needing non-GPT models (Claude, Gemini, open-source LLMs)

Quick start

curl -X POST https://x402factory.ai/base/llm/gpt \
  -H "Content-Type: application/json" \
  -H "X-PAYMENT: <x402-payment-header>" \
  -d '{"message": "What is the x402 protocol?", "model": "gpt-5-mini", "max_output_tokens": 2000}'

Example

Request

{
  "model": "gpt-5-mini",
  "action": "message",
  "message": "Explain the x402 payment protocol in two sentences.",
  "max_output_tokens": 2000
}

Response

{
  "ok": true,
  "model": "gpt-5-mini",
  "reply": "The x402 protocol enables pay-per-use API access by embedding USDC micropayments directly into HTTP requests. It eliminates the need for API keys or accounts — your wallet is your identity.",
  "action": "call",
  "price_usdc": 0.01,
  "max_output_tokens": 2000,
  "estimated_input_tokens": 12
}

Endpoint

URLhttps://x402factory.ai/base/llm/gpt
Transporthttp
Protocolx402
Pay to0x402FaCcC3fAeb72351CC2b68C7966faF5f22B0d4
CurrencyUSD COIN

Quality

0.78/ 1.00

The x402 challenge is live and returns a detailed outputSchema with full input/output field descriptions and pricing logic. However, there are no separate docs, no OpenAPI spec, and the crawled /docs, /api, /pricing, and /README pages all return 404, so documentation beyond the challenge payload is absent.

Warnings

  • —No dedicated documentation pages found — /docs, /api, /pricing, /README all return 404
  • —No OpenAPI specification available
  • —Response example is inferred from the outputSchema, not from an actual successful call
  • —Model names reference 'gpt-5' variants which may be internal aliases; actual OpenAI model mappings are not documented

Citations

Provenance

Indexed fromx402_bazaar
Enriched2026-04-18 19:30:34Z · anthropic/claude-opus-4.6 · v2
First seen2026-04-18
Last seen2026-04-24

Agent access

JSONhttps://clawmart.sh/api/listings/p4VK7C
Pay-per-use GPT endpoint on Base via x402 — no API keys, just USDC micropayments. — Clawmart · Clawmart