Providers

Every provider answers the same ten questions with the same shapes. What changes underneath is the API, where the key travels, how a page says there's a next one, and which operations exist at all. The pages are short on purpose. The part worth reading is the gotcha list on each one, because that's where the afternoons go.

listProviders()19 providers · registry order

			Operations
Etherscan	key	10 chains	bal: served his: served tx: served utx: absent key: absent con: served tok: served trf: served gas: served blk: served	8 of 10
Blockscout	none	10 chains	bal: served his: served tx: served utx: absent key: absent con: served tok: served trf: served gas: served blk: served	8 of 10
Blockchair	optional	7 chains	bal: served his: served tx: served utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: served	4 of 10
Mempool	none	3 chains	bal: served his: served tx: served utx: served key: served con: absent tok: absent trf: absent gas: served blk: served	7 of 10
Blockstream	none	1 chain	bal: served his: served tx: served utx: served key: served con: absent tok: absent trf: absent gas: absent blk: served	6 of 10
Solscan	key	1 chain	bal: served his: served tx: served utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: served	4 of 10
Helius	key	1 chain	bal: absent his: served tx: served utx: absent key: absent con: absent tok: served trf: absent gas: absent blk: absent	3 of 10
TONAPI	none	1 chain	bal: served his: served tx: absent utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: absent	2 of 10
TRONSCAN	key	1 chain	bal: served his: served tx: served utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: served	4 of 10
Aptos Explorer	none	1 chain	bal: absent his: absent tx: absent utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: absent	0 of 10
Blockberry	key	1 chain	bal: served his: served tx: absent utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: absent	2 of 10
Koios	none	1 chain	bal: served his: served tx: served utx: absent key: absent con: absent tok: served trf: absent gas: absent blk: absent	4 of 10
Arweave gateway	none	1 chain	bal: served his: served tx: served utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: served	4 of 10
dcrdata	none	1 chain	bal: served his: served tx: served utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: served	4 of 10
Horizon	none	1 chain	bal: served his: served tx: served utx: absent key: absent con: absent tok: served trf: served gas: served blk: served	7 of 10
WhatsOnChain	optional	1 chain	bal: served his: served tx: served utx: served key: absent con: absent tok: absent trf: absent gas: absent blk: served	5 of 10
Blockbook	none	1 chain	bal: served his: served tx: served utx: served key: absent con: absent tok: absent trf: absent gas: absent blk: served	5 of 10
Haskoin	none	1 chain	bal: served his: served tx: served utx: served key: absent con: absent tok: absent trf: absent gas: absent blk: served	5 of 10
eCash Explorer	none	1 chain	bal: absent his: served tx: absent utx: absent key: absent con: absent tok: absent trf: absent gas: absent blk: served	2 of 10

Four families

EVM, ten chains each. Etherscan and Blockscout each serve ten EVM chains and every operation. Etherscan needs a key and answers in one v2 endpoint with a chain id; Blockscout needs nothing and has one host per chain. With a key you get Etherscan first, without one Blockscout, and either way a rate limit on the first moves the read to the other.

Bitcoin and its relatives. Mempool for Bitcoin, Litecoin and Pepecoin through mempool.space and its siblings, Blockstream for Bitcoin through the Esplora API as an independent second backend, Blockchair for Bitcoin, Bitcoin Cash, Litecoin, Dogecoin, Ethereum, eCash and Zcash through one dashboard API, dcrdata for Decred through Insight, WhatsOnChain for Bitcoin SV, Blockbook for Bitcoin Gold through btgexplorer.com, and Haskoin for Bitcoin Cash through api.haskoin.com. eCash Explorer reads eCash history and blocks from explorer.e.cash and leaves the balance to Blockchair. Mempool, Blockstream, WhatsOnChain, Blockbook and Haskoin are the only ones with unspent outputs.

One chain, with a key. Solscan and Helius on Solana, TRONSCAN on TRON, Blockberry on Sui. Each throws UnsupportedChainError for any other chain and AuthError without its key.

Adding one

A new backend is one class, one key, one entry in builtins and one line in the build config. Custom providers walks through it; the registry test refuses a provider that skips a step.