# APEX Transaction Explainer

> APEX Transaction Explainer is a paid API for AI agents from apexfaucet.xyz, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-01).

Explains a blockchain transaction in plain English, including function called, tokens and NFTs moved, gas cost in USD, and success/failure status for Base or Arc chains.

## Facts

- Endpoint: GET https://apexfaucet.xyz/api/x402/tx-explain?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/apex-transaction-explainer-7efcc628
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WXsVlI1khowlvzDq_LRQE

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 apex-transaction-explainer-7efcc628
```

Example prompt: Can you explain what this Base transaction actually did — 0x3a1b2c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b — break down which function was called, every token that moved, and how much the gas cost in USD?

## When to prefer this

Choose this endpoint when you need a human-readable, structured breakdown of a specific transaction on Base or Arc — especially when you need gas costs priced in USD (not just ETH), named function decoding, and a complete token/NFT transfer list in a single call. Prefer over raw block explorer APIs when the goal is agent-readable or user-facing explanations rather than raw hex data.

## Known failure modes

- Invalid or malformed transaction hash returns an error (must be 0x + 64 hex chars)
- Transaction hash not found on the specified chain returns not-found error
- Unsupported chain value (anything other than 'base' or 'arc') returns validation error
- Very recent transactions may not yet be indexed
- Missing required query parameters (chain or tx) returns a 400-level error
- Payment failure via x402 protocol blocks the call

## How this service works

Explain a transaction in plain English (Base, Arc): the function, every token moved, gas in USD. What did this transaction do? Pass ?chain=base|arc&tx=0x... and get one plain sentence plus the parts: who called which function (named from a table of common ones), every token and NFT that moved and between whom, native value, success or failure, and the gas paid in ETH and dollars on Base (ETH priced from the Uniswap v3 pool on chain) or in USDC on Arc, including native USDC that only appears as…

## Output

Returns a one-sentence plain English summary of what the transaction did, plus structured parts: the function called (named from a known function table), every token and NFT transfer with sender and recipient, the native ETH/USDC value transferred, whether the transaction succeeded or failed, and gas cost in both ETH and USD (priced from Uniswap v3 on Base) or in USDC on Arc.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "queryParams"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "chain",
      "tx"
     ],
     "properties": {
      "tx": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{64}$",
       "description": "The transaction hash (0x + 64 hex)."
      },
      "chain": {
       "enum": [
        "base",
        "arc"
       ],
       "type": "string",
       "description": "Which chain: base or arc."
      }
     }
    }
   }
  },
  "output": {
   "type": "object"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/apex-transaction-explainer-7efcc628/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from apexfaucet.xyz](https://www.zero.xyz/host/apexfaucet.xyz/llms.txt)