# fastapi.online — Latest Block Lookup

> fastapi.online — Latest Block Lookup is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.0005/call, status down (last checked 2026-10-30).

Returns the latest block number and metadata for a specified EVM-compatible blockchain network

## Facts

- Endpoint: POST https://api.fastapi.online/latest-block?utm_source=zero.xyz
- Price: $0.0005/call
- Payment: x402
- Status: down
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastapi-online-latest-block-lookup-214ba8c5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_PFfbTCGHPCqXUYXhk15QO

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-latest-block-lookup-214ba8c5 -d '<json body>'
```

Example prompt: What is the latest block number on Base right now?

## When to prefer this

Use this endpoint when you need a quick, pay-per-call lookup of the current block height or latest block metadata on a major EVM network without needing a full blockchain node or RPC subscription. Particularly useful for lightweight agents that need occasional blockchain state checks without ongoing infrastructure costs.

## Known failure modes

- Unsupported chain name returns a validation error
- Network connectivity issues may cause timeouts
- Payment failure (insufficient USDC) results in HTTP 402 before processing

## 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 the latest block number and associated metadata (such as timestamp, hash, or block height) for the specified EVM-compatible chain (ethereum, base, polygon, arbitrum, or optimism).

## Request schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastapi-online-latest-block-lookup-214ba8c5/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)