Web search API: search results for AI agents

Web search API for AI agents and apps: search results for a query, ready for agent consumption, for $0.005 USDC per call through x402 on Base. Cached results, no signup, no API key.

Endpoint

POST https://apisphere.us.ci/api/v1/web-search returns search results for a query, powered by DuckDuckGo Instant Answer and search APIs. A plain GET only advertises the x402 payment challenge - send data over POST.

Price: $0.005 USDC per call, settled on Base through x402.
Freshness: results cached for 15 minutes (NEAR_REAL_TIME).
Results are limited to 1-10 per request (default 5).

Request fields

Send a JSON body. Invalid bodies return 400 with field-level details.

query (required): 1 to 500 characters - the search query.
limit (optional): integer from 1 to 10, defaults to 5.

Paid request

curl -X POST https://apisphere.us.ci/api/v1/web-search   -H "Content-Type: application/json"   -H "X-PAYMENT: <signed-payment-payload>"   -d '{"query": "latest AI developments"}'

Response

A 200 response returns the query, an abstract, heading, and a results array with titles, URLs, and snippets, plus a meta block with the request id and latency.

400 - invalid query or limit (details in the response).
402 - missing or invalid payment.
429 - rate limited; honor Retry-After.
502 - upstream provider error; the same request is safe to retry.

Example 200 body

{
  "query": "latest AI developments",
  "abstract": "AI refers to the simulation of human intelligence...",
  "heading": "Artificial intelligence",
  "results": [
    {
      "title": "Artificial intelligence",
      "url": "https://en.wikipedia.org/wiki/Artificial_intelligence",
      "snippet": "Wikipedia: AI is the intelligence...",
      "source": "DuckDuckGo"
    }
  ],
  "related_topics": ["Machine learning", "Neural networks"],
  "meta": {
    "cache": "miss",
    "request_id": "7f3a9c2e-1b4d-4f6a-8c2e-9d1f5a3b7c4e",
    "latency_ms": 142
  }
}