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The IndexerService exposes a set of gRPC and REST endpoints that allow clients to query commitment transactions, inspect VTXO trees, monitor forfeit and sweep transactions, and subscribe to real-time updates for script activity. The IndexerService supports both point-in-time queries and real-time subscriptions.
API references can be found here and a set of tools to handle protobuf specifications can be found here.

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API Layer Logic

Client applications use the IndexerService to:
Operation CategoryMethodsPurpose
Commitment DataGetCommitmentTx, GetForfeitTxs, GetConnectorsCommitment tx analysis
VTXO ManagementGetVtxos, GetVtxoTree, GetVtxoTreeLeavesVTXO lifecycle and tree navigation
Transaction HistoryGetVtxoChain, GetVirtualTxsTransaction chain analysis
Batch OperationsGetBatchSweepTransactionsBatch settlement tracking
Real-time MonitoringSubscribeForScripts, GetSubscriptionScript-based event subscriptions
This service is essential for builders who want to provide visibility into user funds, transaction history, or batch-level activity without relying on custom indexers or database infrastructure.

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API Layer Logic Explained

These functions provide comprehensive analysis of commitment transactions and their associated components.
  • GetCommitmentTx returns information (via GetCommitmentTxResponse) about a specific commitment transaction (identified via its TxId), including its associated batches, input/output amounts, and start/end timestamps
  • GetForfeitTxs returns the list of forfeit transactions submitted for a given commitment transaction
  • GetConnectors returns the tree of connector outputs with details on tree positioning for the provided commitment transaction
The responses for GetForfeitTxs and GetConnectors support pagination if results span multiple pages.
VTXO lifecycle and tree navigation functions enable clients to query and traverse the state of virtual transactions.
  • GetVtxos provides flexible VTXO querying by addresses or outpoints with filtering options for spendable, spent only, or recoverable states
  • GetVtxoTree returns the complete VTXO tree structure for a given batch outpoint, including transaction details and tree positioning information
  • GetVtxoTreeLeaves returns the list of leaves (VTXO outpoints) of the tree(s) for a batch outpoint, optimized for clients that only need the final outputs
Offchain transaction chain analysis tools in the virtual mempool enable tracing of VTXO spending flows and virtual transaction data
  • GetVirtualTxs returns the raw virtual transactions (in hex) for a given set of Arkade transaction IDs
  • GetVtxoChain traces the lineage of Arkade transactions from any VTXO leaf spending through to the creation of a specified VTXO outpoint (ie. tx chain), enabling full transaction history reconstruction
Batch settlement tracking provides visibility into the sweep transactions that claim batch outputs back to the operator.
  • GetBatchSweepTransactions returns the list of transactions that were swept by a given batch output and includes information on whether a batch output has been claimed by the operator after expiry or if a user has initiated unrolling of the tree.
In normal operation, this contains a single transaction ID representing the complete batch claim. However, if any tree leaves were unrolled onchain before expiration, the list contains multiple transaction IDs representing the partial sweeps. For example, in a binary tree with 4+ leaves, one unroll triggers 3 sweep transactions for the remaining tree. If an entire VTXO tree was unrolled onchain, the sweep transaction list is empty.
Script-based event subscription system enables clients to receive real-time notifications for transactions affecting specific VTXO scripts.
  • SubscribeForScripts allows clients to create or update subscriptions for transaction notifications related to specific VTXO scripts, returning a subscription ID for stream access
  • GetSubscription provides server-side streaming of real-time notifications for subscribed scripts, delivering transaction details including new and spent VTXOs, transaction data, and checkpoint transactions
  • UnsubscribeForScripts lets a client remove specific scripts from existing subscriptions

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Notes for Builders

  • Use script-level subscriptions to drive reactive clients or backend workflows
  • VTXO queries and chain tracing allow for full lifecycle auditing of offchain funds
  • Tree navigation is optimized - use GetVtxoTreeLeaves for efficiency when you only need final outputs, not the full tree structure
  • Batch sweep tracking helps monitor operator claims - GetBatchSweepTransactions shows normal vs. partial sweep scenarios when leaves are unrolled onchain
  • Real-time subscriptions are stateful - manage the subscription lifecycle with SubscribeForScripts / UnsubscribeForScripts before using GetSubscription streams
  • All methods support both gRPC and REST interfaces through auto-generated gateway mappings
  • All endpoints are paginated and follow REST conventions
The IndexerService is complementary to the ArkService. Use the IndexerService for historical transaction data and detailed analysis and ArkService for real-time updates
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