Ordinals Indexer

An on-chain Bitcoin Ordinals indexer running entirely inside an Internet Computer (ICP) canister.

Ordinals Indexer is Omnity Network’s second on-chain indexer after the Runes Indexer. It is deployed on the Internet Computer and implements essentially all indexing functionality of ord except for runes indexing.

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Overview

Ordinals Indexer is a fully on-chain implementation of the Bitcoin Ordinals protocol:

• Runs 100% inside an ICP canister
  No centralized servers, no custom indexer infra, no trusted API gateway.

• Indexes the Bitcoin chain from genesis
  All Bitcoin blocks are fetched, verified, and indexed onchain using ICP’s native Bitcoin integration.

• Ord-compatible indexing (minus runes)
  Mirrors ord’s logic for sats, sequence numbers, inscription numbers, and inscription IDs, but does not index runes.

• Production-ready infrastructure
  Builds on the same architecture as the on-chain Runes Indexer, which already powers the majority of Runes issuance and trading activity on ICP.

Deployment

We deploy Ordinals Indexer for both Bitcoin mainnet and testnet4 on ICP.

• Testnet canister ID

  krhn4-hiaaa-aaaao-qkb3a-cai

• Mainnet canister ID

  t5v7z-6iaaa-aaaai-atihq-cai

You can view the canisters on the ICP dashboard:

• Mainnet: https://dashboard.internetcomputer.org/canister/t5v7z-6iaaa-aaaai-atihq-cai
• Testnet: https://dashboard.internetcomputer.org/canister/krhn4-hiaaa-aaaao-qkb3a-cai

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API Reference

At the moment, Ordinals Indexer exposes a single public query endpoint.

get_inscriptions_for_output

get_inscriptions_for_output : (text) -> (Result) query;

• Input

  • text: A Bitcoin output specified as txid:vout, e.g.
    aae1abaa3ddd45acfce1eac4b186043b863c75caadc7d73cd2e17a6e33337cd6:1

• Return

  • variant { Ok = opt vec text; Err = text }
    On success, returns an optional vector of inscription IDs attached to that output.

• Example

  get_inscriptions_for_output(
    "aae1abaa3ddd45acfce1eac4b186043b863c75caadc7d73cd2e17a6e33337cd6:1"
  )
  
  =>
  (variant {
    Ok = opt vec {
      "a98b955bda5992ff7724704926c178fee2594864700f718204193202b6346227i0"
    }
  })
  

Currently this is the only public API, but internally the indexer maintains full Ordinals state, including:

• Sat assignments
• Sequence number
• Inscription number
• Inscription ID

If you need additional query APIs (e.g. lookups by sat, inscription number, or other ord-compatible views), please open an issue or contact the Omnity team — the canister is ready to expose more endpoints as needed.

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Design and Architecture

Ordinals Indexer shares the same high-level architecture as Runes Indexer:

• Data source: Bitcoin RPC provider

  • The canister continuously fetches Bitcoin blocks through HTTPS outcalls to a Bitcoin RPC provider.

• Verification: ICP Bitcoin canister

  • All blocks are verified using ICP’s native Bitcoin integration.
  • The indexer is designed to correctly handle Bitcoin chain reorganizations (reorgs).

• Storage: Stable memory as Ord-like KV store

  • Ord’s redb key-value database is replaced by canister stable memory in this implementation.
  • This enables persistence across canister upgrades and supports the large dataset required for sats and inscriptions.

• Scalability: Cycles-aware incremental indexing

  • Bitcoin mainnet currently has roughly:
    • ~330M UTXOs
    • ~110M inscriptions
  • Ordinals indexing is computationally heavy and cannot be processed in a single call per block.
  • The canister introduces multiple checkpoints / breakpoints during block processing and completes the indexing of a block over multiple iterations, respecting cycles limits and ICP execution constraints.

This architecture allows the entire Ordinals protocol logic to execute onchain while remaining practical and cost-efficient.

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License

The license will follow that of the runes-indexer project (see the repository’s LICENSE file for exact terms).