# TraceFast Block Address State Changes

> TraceFast Block Address State Changes is a paid API for AI agents from mpp.tracefast.xyz, paid per call via x402, $0.025/call, status unknown (last checked 2026-10-15).

Returns all Ethereum accounts whose native state (balance, nonce, or code) changed in a given block, with before/after balance deltas, sorted by address

## Facts

- Endpoint: GET https://mpp.tracefast.xyz/api/v1/chains/1/blocks/:number/addresses?utm_source=zero.xyz
- Price: $0.025/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/tracefast-block-address-state-changes-bb013606
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_x5hnFcrSgd8tTG8FQeb7Q

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 tracefast-block-address-state-changes-bb013606
```

Example prompt: Can you pull all the Ethereum accounts whose native balance, nonce, or code changed in block 21500000, and show me what changed including the before and after balances? Give me the first 25 results.

## When to prefer this

Use this endpoint when you need a comprehensive, ordered list of every account whose native Ethereum state (balance, nonce, or code) changed within a specific block — ideal for forensic analysis, MEV detection, block-level auditing, or monitoring contract deployments. Prefer this over transaction-level endpoints when you want account-centric state change summaries rather than individual transaction traces.

## Known failure modes

- Invalid block number (block not yet mined or malformed) returns an error
- Limit out of range (must be 1–100) returns a validation error
- Invalid or expired cursor returns a pagination error
- Block with no state changes may return an empty result set
- Network congestion may cause delayed responses for very recent blocks

## How this service works

TraceFast live Ethereum data: every account whose own state — native balance, nonce or code — changed in one block, with what changed and the balance before and after, in address order. Path number: Block height. Query limit: 1..=100, default 25; cursor: `nextCursor` of the previous page. Docs: https://docs.tracefast.xyz/api/block-addresses.md

## Output

A paginated list of Ethereum addresses (sorted by address) whose native state changed in the specified block. Each entry includes the address, what changed (balance, nonce, and/or code), the balance before the block, and the balance after the block. A nextCursor field is included when more results are available beyond the current page.

## Request schema (JSON Schema)

```json
{
 "properties": {
  "input": {
   "required": [
    "method"
   ],
   "properties": {
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/tracefast-block-address-state-changes-bb013606/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mpp.tracefast.xyz](https://www.zero.xyz/host/mpp.tracefast.xyz/llms.txt)