# fastapi.online — Blockchain Address Info Lookup

> fastapi.online — Blockchain Address Info Lookup is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-29).

Looks up metadata and information about a blockchain address on a specified EVM-compatible chain

## Facts

- Endpoint: POST https://api.fastapi.online/address-info?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastapi-online-blockchain-address-info-lookup-a28126fd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_kNGgdlHbRtNvm2PEhloyV

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 fastapi-online-blockchain-address-info-lookup-a28126fd -d '<json body>'
```

Example prompt: Can you look up info for the address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Ethereum?

## When to prefer this

Choose this endpoint when you need quick, pay-per-call blockchain address lookups across major EVM chains (Ethereum, Base, Polygon, Arbitrum, Optimism) without signup. Ideal for agents that need on-demand address enrichment with no API key commitment and micro-payment pricing via crypto.

## Known failure modes

- Invalid address format returns an error
- Unsupported chain value (outside the allowed enum) returns validation error
- Address not found or no data available on the specified chain
- Network or RPC connectivity issues for the target chain
- Payment failure or insufficient USDC balance

## How this service works

Chat, embeddings, OCR, speech-to-text, image editing, image understanding (captioning/Q&amp;A), text-to-speech, translation, writing tools, classification tools, developer tools, local utilities, format/checksum validators, encoding &amp; crypto utilities, date/time calculators, geo/coordinate math, math &amp; finance calculators, novelty tools, and business/social writing generators — 179 endpoints in all, across multiple specialized self-hosted models. Pay per call with crypto — no signup — or get an API key.

## Output

Returns metadata and on-chain information about the queried blockchain address on the specified EVM-compatible chain, which may include contract status, transaction history indicators, labels, or other available address attributes.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "chain": {
   "enum": [
    "ethereum",
    "base",
    "polygon",
    "arbitrum",
    "optimism"
   ],
   "type": "string"
  },
  "address": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastapi-online-blockchain-address-info-lookup-a28126fd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.fastapi.online](https://www.zero.xyz/host/api.fastapi.online/llms.txt)