# ChainRay Watch Diff

> ChainRay Watch Diff is a paid API for AI agents from chainray.online, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-22).

Retrieves the diff/changes for a specific blockchain watch subscription by watchId, enabling real-time monitoring of on-chain state changes.

## Facts

- Endpoint: GET https://chainray.online/watch-diff/%7BwatchId%7D?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/chainray-watch-diff-9fb89701
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8dtqotFTwOJOoHFEnqNSu

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 chainray-watch-diff-9fb89701
```

Example prompt: Check what changed on-chain for my watch subscription ID 'abc123' on the Base network — pull the latest diff so I can see what state updates occurred.

## When to prefer this

Use this endpoint when you have already registered a watch subscription on ChainRay and need to poll for incremental on-chain changes (diffs) rather than querying full state. Ideal for event-driven agents that need to react to blockchain state changes without re-fetching entire datasets. Prefer this over full data pulls when monitoring specific addresses, contracts, or positions over time.

## Known failure modes

- Invalid or expired watchId returns 404 or empty diff
- Unsupported chain parameter results in 400 error
- Payment failure via x402 returns 402 Payment Required
- Watch subscription has been deleted or timed out
- Network congestion causes delayed or stale diff data
- Rate limiting if polling too frequently

## How this service works

Blockchain data and intelligence service for AI agents. 93 paid capabilities / 94 HTTP route templates across 57 supported networks, from gas fees to DeFi analytics, with real-time streams, intent routing, and verifiable proofs. Pay-per-request via x402.

## Output

Returns a structured diff object representing what changed on-chain since the last poll for the given watchId. Typically includes changed state fields, transaction events, block numbers, and timestamps of detected changes across the specified blockchain network.

## 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"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "chain": {
       "type": "string",
       "description": "Blockchain network (e.g., base, ethereum, polygon)"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/chainray-watch-diff-9fb89701/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from chainray.online](https://www.zero.xyz/host/chainray.online/llms.txt)