Provider internals
Every Blaze provider implements the same Provider surface for protocol parameters, UTxO lookups, datum resolution, transaction evaluation, transaction submission, and script-reference resolution.
Routing
RoutedProvider forwards each operation to the configured provider. Chain reads normally go to queryProvider, script evaluation goes to evaluationProvider, and submission or confirmation calls go to submissionProvider. perOperation overrides take priority when one backend has a stronger implementation for a specific call.
Debug logging is emitted around routed calls only when a debugLogger is configured. The logger receives the operation name, provider object, original parameters, status, elapsed time, and thrown error where relevant. Applications should redact parameters before writing logs if they include addresses, transaction bodies, API keys, or user-specific data.
Provider behavior
Blockfrost, Maestro, and Kupmios differ in how they resolve data. Blockfrost and Maestro are HTTP-first providers. Kupmios combines Kupo for indexed UTxO queries with Ogmios for ledger-state, evaluation, submission, and websocket chain sync.
Provider.resolveScriptRef is abstract. Providers with a native script-reference index should use it. Providers that only expose address UTxOs can call findScriptRefInAddressUtxos, but that scan has to be an explicit provider decision.
Backend requests
Blockfrost requests protocol parameters with GET epochs/latest/parameters. Address reads page through GET /addresses/{address}/utxos?count=100&page={page}. Asset reads use GET /addresses/{address}/utxos/{policyId}{assetName}?count=100&page={page}. NFT lookup first calls GET /assets/{policyId}{assetName}/addresses, then resolves the address UTxO set. Input resolution calls GET /txs/{txId}/utxos, datum lookup calls GET /scripts/datum/{datumHash}/cbor, confirmation checks GET /txs/{txId}/metadata/cbor, transaction submission calls POST /tx/submit, and evaluation calls POST /utils/txs/evaluate/utxos. Script-reference hydration calls GET /scripts/{scriptHash} and GET /scripts/{scriptHash}/cbor; Blockfrost.resolveScriptRef calls GET /scripts/{scriptHash}/utxos and filters by address only when the caller supplies one.
Maestro requests protocol parameters with GET /protocol-parameters. Address reads call GET /addresses/{address}/utxos?with_cbor=true&count=100, or the credential route when a payment credential is used. Asset reads add asset={policyId}{assetName}. NFT lookup calls GET /assets/{policyId}{assetName}/utxos?count=2, then resolves the selected output with GET /transactions/{txId}/outputs/{index}/txo?with_cbor=true. Input resolution calls POST /transactions/outputs?with_cbor=true, datum lookup calls GET /datums/{datumHash}, confirmation checks GET /transactions/{txId}/cbor, transaction submission calls POST /txmanager, and evaluation calls POST /transactions/evaluate. Maestro address reads return full transaction-output CBOR, so Maestro.resolveScriptRef explicitly scans address UTxOs until Maestro exposes a direct script-reference lookup.
Kupmios uses Kupo for indexed reads and Ogmios for ledger operations. Address reads call Kupo GET /matches/{address}?unspent. Asset reads call Kupo with policy_id={policyId}&asset_name={assetName} when an address is supplied, or GET /matches/{policyId}.{assetName}?unspent for asset-only lookup. Input resolution calls Kupo GET /matches/{index}@{txId}?unspent. Datum and script hydration call GET /datums/{datumHash} and GET /scripts/{scriptHash}. Protocol parameters, submission, and evaluation go through Ogmios ledger-state, submit-transaction, and evaluate-transaction calls. Websocket events use Ogmios local-chain-sync by sending findIntersection before requesting blocks with nextBlock.
Caching boundaries
The query cache lives above providers. It does not change provider behavior, mutate results, or cache transaction evaluation and submission. Prefer short TTLs for wallet-facing UI reads and longer TTLs for reference data such as script-reference lookups.