OpenAI-compatible chat completions paid per call in USDC

OpenAI-compatible chat completions paid per call in USDC: point any OpenAI SDK at this base URL and send a normal chat request, with the model chosen from a curated list and streaming supported. Use it when an agent needs a model answer without an API key or an account, one call at a time, with a receipt for each.

Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.

Endpoint

POST https://agent402.tools/v1/chat/completions

Our checks, last 30 days

We never call tools that send, buy, move money or file anything, not even without paying.

Example input (from the provider)

{
  "body": {
    "max_tokens": 5,
    "messages": [
      {
        "content": "Reply with exactly: OK",
        "role": "user"
      }
    ],
    "model": "openai/gpt-4o-mini"
  },
  "bodyType": "json",
  "method": "POST",
  "type": "http"
}

Promised output schema (from the provider)

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "properties": {
    "input": {
      "additionalProperties": false,
      "properties": {
        "body": {
          "properties": {
            "cache_control": {
              "description": "Optional - prompt caching preference. Default ON ({type:\"ephemeral\"}, 5-minute TTL): repeated prefixes across your turns are served from the provider cache (same price to you). Send false to disable. ttl:\"1h\" is not offered."
            },
            "max_completion_tokens": {
              "description": "Optional - alias of max_tokens (newer OpenAI SDKs send this).",
              "type": "integer"
            },
            "max_tokens": {
              "description": "Output token cap (clamped to the tier maximum)",
              "type": "number"
            },
            "messages": {
              "description": "OpenAI chat messages: [{role, content}] - text and image_url content blocks supported",
              "type": "array"
            },
            "model": {
              "description": "Model id - OpenRouter form (openai/gpt-4o-mini) or bare OpenAI form (gpt-4o-mini). GET /v1/models lists the allowlist per tier. Optional: omit it and the tier serves its documented default (x402.defaultModel on /v1/models), named back in agent402_default_model; the price does not change",
              "type": "string"
            },
            "reasoning": {
              "description": "Optional - {effort: \"none\"|\"minimal\"|\"low\"|\"medium\"|\"high\"|\"xhigh\"|\"max\", max_tokens?, exclude?, enabled?}. Reasoning tokens count against max_tokens. Omitted: low effort on the budget tiers, the model default on premium. reasoning_effort (string) is accepted as an alias.",
              "type": "object"
            },
            "tools": {
              "description": "Optional - OpenAI function tools {type:\"function\", function:{...}}, or a tool namespace {type:\"namespace\", name, tools:[...]} (flattened into its functions). The pro and premium routes also accept the bounded server tools openrouter:web_search, openrouter:web_fetch and openrouter:datetime with server-owned limits (GET /v1/models lists them); stop_server_tools_when and max_tool_calls are refused. A request with a server tool is never served from the prompt cache.",
              "type": "array"
            },
            "zdr": {
              "description": "Optional - true routes only to zero-data-retention providers (OpenRouter provider.zdr); the only provider preference a caller may set.",
              "type": "boolean"
            }
          },
          "required": [
            "messages"
          ]
        },
        "bodyType": {
          "enum": [
            "json",
            "form-data",
            "text"
          ],
          "type": "string"
        },
        "method": {
          "enum": [
            "POST"
          ],
          "type": "string"
        },
        "type": {
          "const": "http",
          "type": "string"
        }
      },
      "required": [
        "type",
        "method",
        "bodyType",
        "body"
      ],
      "type": "object"
    },
    "output": {
      "properties": {
        "example": {
          "properties": {
            "choices": {
              "items": {
                "type": "object"
              },
              "type": "array"
            },
            "created": {
              "type": "integer"
            },
            "id": {
              "type": "string"
            },
            "model": {
              "type": "string"
            },
            "object": {
              "type": "string"
            },
            "usage": {
              "properties": {
                "completion_tokens": {
                  "type": "integer"
                },
                "prompt_tokens": {
                  "type": "integer"
                },
                "total_tokens": {
                  "type": "integer"
                }
              },
              "type": "object"
            }
          },
          "required": [
            "id",
            "object",
            "created",
            "model",
            "choices",
            "usage"
          ],
          "type": "object"
        },
        "type": {
          "type": "string"
        }
      },
      "required": [
        "type"
      ],
      "type": "object"
    }
  },
  "required": [
    "input"
  ],
  "type": "object"
}

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