Blockscout vs Watchdata

Blockscout is the open-source, EVM-compatible block explorer behind dozens of public chain explorers (Ethereum mainnet, its L2s, and more), and its REST v2 API exposes the same block, address, token, and transaction data that powers those explorer UIs. No signup or API key is required for the per-instance hosted public REST API, though anonymous callers are rate-limited per endpoint (confirmed live: `x-ratelimit-limit` varies by route, e.g. 180 on an address lookup vs. 10 on `/stats`); docs.blockscout.com also flags this per-instance API for deprecation in favor of a separate, paid, API-key-gated multichain "PRO API," though the free per-instance API this entry tracks was still live and keyless as of this run's probe. Every response is JSON.

WatchData operates hosted JSON-RPC nodes across Ethereum, Polygon, BNB Smart Chain, and other networks, plus higher-level "Powered API" endpoints for token balances, transfer history, and block-timestamp lookups that would otherwise require custom indexing. Every call needs an api_key issued from the dashboard after a free signup, with a 100-million-unit free monthly allowance before paid plans apply. Responses are plain JSON-RPC.