# xx402 Base Token Holder Sketch API

> xx402 Base Token Holder Sketch API is a paid API for AI agents from x402.xx402.icu, paid per call via x402, $0.01/call, status down (last checked 2026-10-24).

Returns a probabilistic sketch of ERC20 token holder concentration, whale candidates, and transfer activity on the Base chain for risk analysis.

## Facts

- Endpoint: GET https://x402.xx402.icu/api/base-token-holder-sketch?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: down
- Last checked: 2026-10-24
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/xx402-base-token-holder-sketch-api-ee84cc00
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_nsznEnwJ2Fe_f19MFf-0p

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability xx402-base-token-holder-sketch-api-ee84cc00
```

Example prompt: Can you run a holder sketch on the USDC token at 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base, looking back over 500 blocks and returning up to 15 top holder candidates, so I can see if there are any whale concentration risks?

## When to prefer this

Use this endpoint when you need a fast probabilistic sketch of token holder concentration on the Base chain without running a full indexer query. It is well-suited for pre-trade risk checks, whale dominance screening, and autonomous agent workflows where a $0.01 per-call micropayment via x402 is acceptable. Prefer this over full indexer solutions when speed, cost, and autonomous payment are priorities over exhaustive accuracy.

## Known failure modes

- Invalid token_address format (not a valid 0x ERC20 address) returns error
- window_blocks below minimum of 100 or above 1000 returns validation error
- limit outside 1-20 range returns validation error
- Payment not accepted or insufficient USDC returns 402
- Token with no recent on-chain activity may return empty holder lists
- Network congestion on Base may cause delayed or incomplete data

## How this service works

Paid Base token, wallet, DeFi, chain-read, x402 buyer/seller discovery, and specialized Bitcoin 15-minute Up/Down prediction-market data packets for autonomous agents and risk tools.

## Output

Returns a JSON object containing: a summary, holder concentration decision, priority/review/avoid queues, top observed holders, active whale candidates, contract holder candidates, recent transfer samples, bucket counts, risk flags, risk score, source status, best next products, and a not-financial-advice disclaimer.

## Response schema (JSON Schema)

```json
{
 "keys": [
  "summary",
  "purchase_acceptance",
  "buyer_next_action",
  "next_paid_call",
  "decision_evidence",
  "repeat_purchase_guard",
  "holder_concentration_decision",
  "priority_queue",
  "best_next_products",
  "concentration_breakdown",
  "review_queue",
  "avoid_queue",
  "top_observed_holders",
  "active_whale_candidates",
  "contract_holder_candidates",
  "recent_transfer_sample",
  "bucket_counts",
  "risk_flags",
  "risk",
  "source_status",
  "not_financial_advice",
  "sources"
 ],
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/xx402-base-token-holder-sketch-api-ee84cc00/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.xx402.icu](https://www.zero.xyz/host/x402.xx402.icu/llms.txt)