M
API Matrix

Watchdata API

Blockchain / API Key Intermediate HTTPS
Varies by plan (check documentation)
72 Score
Grade B
Visit Official Site Compare Alternatives

Overview

Watchdata provides a simple JSON-RPC and REST gateway to the Ethereum blockchain, giving you account balances, transaction history, and token data without syncing a node. It suits developers who want Ethereum data access with minimal setup.

💡

Beginner Tip

Pass your API key as a query parameter (?api_key=YOUR_KEY) rather than a header — Watchdata's docs show both but the query param approach is simpler for quick testing with curl or a browser.

Available Data

Watchdata data via REST API
JSON-formatted response data
Requires API key authentication

Example Response

JSON Response 
{
  "id": "bitcoin",
  "symbol": "btc",
  "current_price": 65432.1,
  "market_cap": 1280000000000,
  "price_change_24h": 1250.5,
  "price_change_percentage_24h": 1.95,
  "total_volume": 28500000000
}

Field Reference

jsonrpc JSON-RPC protocol version, always 2.0
id Echoes the request ID you sent, useful for matching async responses
result Hexadecimal value returned by the method; for eth_getBalance this is the balance in wei
error Present only on failure; contains code (integer) and message (string) describing what went wrong
error.code Standard JSON-RPC error code, e.g. -32602 for invalid params

Implementation Example 

const url = "https://docs.watchdata.io/";
// Replace headers or query params with the values required by this API.
const response = await fetch(url, {
  headers: {
  "X-API-Key": "YOUR_API_KEY"
  }
});
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

403 Forbidden API key missing, invalid, or plan quota exceeded
✓ Check your key at the Watchdata dashboard and ensure your plan supports the method you are calling
Invalid address format Ethereum address passed without the 0x prefix or with wrong length
✓ Always pass 42-character addresses starting with 0x, e.g. 0xAbCd...1234
Method not supported Calling a JSON-RPC method your plan does not include
✓ Review the Watchdata plan comparison page; upgrade or switch to a supported REST endpoint instead

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 5/20
🔒 Security 15/15
🛠 Developer XP 12/20
✓ Reliability 10/15

Partially tested on Apr 5, 2026

Technical Specifications

Auth API Key
HTTPS REQUIRED
CORS UNKNOWN
Category Blockchain
Difficulty Intermediate
Verified: 2026-04-04

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