Substrate API Sidecar (AssetHub + Relaychain)
Substrate API Sidecar REST reference for Polkadot Asset Hub and Relaychain. Explore endpoint list, request examples, and how to connect to GetBlock's Polkadot endpoints
Substrate API Sidecar is a REST service that runs on top of a Substrate node and returns decoded JSON, allowing clients to read chain data without computing storage keys or decoding SCALE. It complements the JSON-RPC surfaces with high-level, ready-to-use endpoints for accounts, blocks, staking, pallets, and transactions.
Networks
On GetBlock's unified endpoint, Asset Hub is the default network and the Relaychain is reached with an /rc path prefix:
curl 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/blocks/head'curl 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/rc/blocks/head'Account, block, staking, and pallet endpoints work on both networks. Asset endpoints (assets, foreign assets, NFTs) are specific to Asset Hub; parachain (/paras) endpoints are specific to the Relaychain.
Available Endpoints
Accounts
GET /accounts/{accountId}/balance-info
Returns the balance details for an account: free, reserved, and frozen amounts, the nonce, and any balance locks, at the latest or a specified block
GET /accounts/{accountId}/staking-info
Returns the staking information for a stash account, including the controller, reward destination, and the bonded, active, and unlocking amounts
GET /accounts/{accountId}/asset-balances
Returns an account's balances for asset hub assets
GET /accounts/{accountId}/vesting-info
Returns the vesting schedules for an account, including the locked amount, the per-block unlock, and the starting block of each schedule
GET /accounts/{accountId}/convert
Converts an account address between ss58 formats and its raw accountid, using the given prefix and scheme
Blocks
GET /blocks/head
Returns the most recent block, including its extrinsics, events grouped by phase, and author
GET /blocks/{blockId}
Returns a block by its number or hash, with decoded extrinsics and events
GET /blocks
Returns a range of blocks in a single call, decoded like /blocks/{blockid}
Node
GET /node/version
Returns the node's client version, implementation name, and the chain it is connected to
GET /node/transaction-pool
Returns the extrinsics currently in the node's transaction pool
Pallets
GET /pallets/{palletId}/storage/{storageItemId}
Returns the decoded value of a storage item in a pallet, resolving the required keys
GET /pallets/{palletId}/consts
Returns the constants defined by a pallet, such as bonding durations or deposit amounts
GET /pallets/staking/progress
Returns the current staking system status: the active era, session progress, and the timing of the next era and unapplied slashes
GET /pallets/assets/{assetId}/asset-info
Returns the details and metadata of an asset hub asset, including its owner, total supply, minimum balance, and its name, symbol, and decimals
GET /pallets/nomination-pools/{poolId}
Returns the details of a nomination pool: its state, points, member count, and bonded account
Runtime
GET /runtime/spec
Returns the runtime specification: the spec name and version, transaction version, and chain properties such as token symbol and decimals
GET /runtime/metadata
Returns the runtime metadata as decoded json
Transaction
GET /transaction/material
Returns the data needed to construct and sign a transaction offline: the genesis hash, chain name, spec and transaction versions, and metadata
POST /transaction
Submits a signed, scale-encoded transaction to the network and returns its hash
POST /transaction/fee-estimate
Estimates the fee and weight for a submitted transaction without broadcasting it
Parachains
GET /paras
Returns the parachains registered on the relay chain and their lifecycle status
GET /paras/leases/current
Returns the current parachain lease period and the parachains that currently hold a lease
Support
Support: support@getblock.io
See Also
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