# Plainchain /v1/fact — Blockchain Fact of the Day

> Plainchain /v1/fact — Blockchain Fact of the Day is a paid API for AI agents from plainchain.appin60.com, paid per call via x402, $0.001042/call, status unknown (last checked 2026-10-14).

Returns a rotating crypto/blockchain historical fact along with a block number, chain name, and index, served pay-per-call via x402 on Base

## Facts

- Endpoint: GET https://plainchain.appin60.com/v1/fact?utm_source=zero.xyz
- Price: $0.001042/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/plainchain-v1-fact-blockchain-fact-of-the-day-4753832a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_baiYu3mYiYQU72m7u8D7t

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 plainchain-v1-fact-blockchain-fact-of-the-day-4753832a
```

Example prompt: Give me one of those Plainchain blockchain history facts — the kind that shows a famous crypto moment with its block number and chain.

## When to prefer this

Choose this endpoint when you want a pre-curated, human-readable blockchain history fact without needing to query chain data yourself. It's ideal for content generation, trivia bots, newsletters, or onboarding UX where you need an engaging crypto fact tied to a real block number. Prefer over raw chain data endpoints when you need narrative content rather than raw on-chain values.

## Known failure modes

- Payment not provided or insufficient USDC via x402 — returns 402 Payment Required
- Malformed x402 payment header — authentication failure
- Service temporarily unavailable — 503 or timeout
- No facts available — edge case returning empty or null payload

## How this service works

Gas, balances, token data, address type, approvals, transaction decoding, x402 receipt verification and verifiable randomness on Base, Arbitrum, Ethereum and Optimism. No API key: pay $0.001-$0.01 per call in USDC on Base via x402.

## Output

A JSON object containing the total number of facts ('of'), the fact text itself ('fact'), a block number ('block'), the chain name ('chain'), and a fact index ('index'). Example: {"of":29,"fact":"On 22 May 2010 Laszlo Hanyecz paid 10,000 BTC for two pizzas...","block":36581662,"chain":"Base","index":1}

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "required": {
   "type": "string"
  },
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "of": 29,
  "fact": "On 22 May 2010 Laszlo Hanyecz paid 10,000 BTC for two pizzas...",
  "block": 36581662,
  "chain": "Base",
  "index": 1
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/plainchain-v1-fact-blockchain-fact-of-the-day-4753832a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from plainchain.appin60.com](https://www.zero.xyz/host/plainchain.appin60.com/llms.txt)