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Overview

Tavily exposes POST /search over the x402 protocol so an AI agent can call it without an API key. The agent sends a request, gets back HTTP 402 with the price, signs a USDC transfer authorization, and retries. Tavily returns the search results in the same response that settles the payment. When the agent’s USDC settles on Base, Tavily captures the payment and releases the result. Refunds for upstream failures are issued back to the agent’s wallet automatically.

Tavily x402 endpoint

https://x402.tavily.com

Machine-readable pricing

GET /.well-known/pricing — current pricing as JSON

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How a paid request works

1

Agent → Tavily

Agent sends POST /search with the search query.
2

Tavily → Agent

Tavily replies 402 with the PAYMENT-REQUIRED header.
3

Agent

Decodes the envelope and signs an EIP-3009 USDC transfer authorization.
4

Agent → Tavily

Retries POST /search with the signed PAYMENT-SIGNATURE header.
5

Tavily

Verifies + settles on Base, then gets search results.
6

Tavily → Agent

Returns 200 with the search results and a PAYMENT-RESPONSE header carrying the on-chain receipt.
The PAYMENT-REQUIRED response header is base64-encoded JSON. Standard x402 client libraries decode it for you; you only need to handle it manually if you’re using your own client. Probe the endpoint to see the raw header: 
curl -i -X POST https://x402.tavily.com/search \
  -H 'content-type: application/json' \
  -d '{"query": "Who is Leo Messi?"}'
Once decoded (e.g. base64 -d | jq), the envelope carries a single accepts entry: 
{
  "x402Version": 2,
  "error": "Payment header is required",
  "resource": {
    "url": "https://x402.tavily.com/search",
    "description": "Tavily Search - advanced mode",
    "mimeType": "application/json"
  },
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "amount": "10000",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "payTo": "0x…deposit-address",
      "maxTimeoutSeconds": 60,
      "extra": {
        "name": "USD Coin",
        "version": "2",
        "tier": "advanced",
        "terms": "By using the Tavily solution, you agree to be bound by the Terms of Use (https://tavily.com/terms) and Privacy Policy (https://tavily.com/privacy) and accept that Tavily disclaims any liability with regard to the AI agent and cryptocurrency payments."
      }
    }
  ]
}
amount is in USDC atomic units (6 decimals). "10000" = $0.01.

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Pricing

EndpointTierPrice
POST /searchadvanced$0.01 / call
Standard Tavily search params (query, topic, max_results, time_range, include_domains, etc.) pass through unchanged; search_depth is always advanced.

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Network and asset

NetworkChain IDAssetContract
Base mainneteip155:8453USDC0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
The agent must sign for the exact atomic amount in amount. The on-chain transfer has to match — under-deposits don’t settle.

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Client integration

Any x402 v2 client works. The wire protocol is what matters; you don’t need a Tavily-specific SDK. 
npx -y awal x402 pay https://x402.tavily.com/search \
  -X POST \
  -d '{"query":"Who is Leo Messi?"}' \
  --json
The client wrapper handles the discovery → sign → retry handshake. From the agent’s point of view it’s a single fetch that costs USDC.

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Response

A successful paid call returns 200 with the standard Tavily search response body plus a PAYMENT-RESPONSE header carrying the on-chain settlement tx hash: 
{
  "query": "Who is Leo Messi?",
  "follow_up_questions": null,
  "answer": null,
  "images": [],
  "results": [
    {
      "title": "Lionel Messi Facts | Britannica",
      "url": "https://www.britannica.com/facts/Lionel-Messi",
      "content": "Lionel Messi, an Argentine footballer, is widely regarded as one of the greatest football players of his generation. Born in 1987, Messi spent the majority of his career playing for Barcelona, where he won numerous domestic league titles and UEFA Champions League titles. Messi is known for his exceptional dribbling skills, vision, and goal",
      "score": 0.81025416,
      "raw_content": null
    }
  ],
  "response_time": 1.5,
  "request_id": "<uuid>"
}
answer, follow_up_questions, images, and auto_parameters are populated only when the caller opts in (include_answer, include_images, auto_parameters in the request body). The minimal-request shape is what’s shown above. Decode the PAYMENT-RESPONSE header to get the receipt: 
{
  "success": true,
  "payer": "0x…agent-wallet",
  "transaction": "0x…base-mainnet-tx-hash",
  "network": "eip155:8453"
}

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Refunds

If the upstream Tavily call fails after the payment has settled, Tavily issues a refund automatically. The refund returns USDC to the wallet that originated the deposit, joined to the original payment via the EIP-3009 nonce. No action from the agent is required.
Refunds route to the wallet that signed the deposit authorization. If the agent paid from an exchange or custodial wallet, the refund lands there. Use a self-custodied wallet for production agents.

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Terms

By using this endpoint you agree to the Terms of Use and Privacy Policy. Tavily disclaims any liability with regard to AI agent behavior and cryptocurrency payments. The same language is surfaced inside the 402 envelope under extra.terms.