EVH.

Ledger signals at the edge of finality

EventHorizon

Notifies event-driven subscriber canisters about relevant transactions

Build a subscription memo

ICP ledger transactions

The protocol

A fast path for ledger-aware canisters.

Event Horizon watches a reviewed ledger and wakes your canister when relevant activity appears. The signal is intentionally lean; your canister remains the source of truth.

01 / Network

Choose an instance.

Configuration is verified against the certified registry before the builder becomes available.

Event Horizon instance

Registry

Operating status

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— Cycles balance

Polling tier · —

Operating status requires JavaScript and public canister status/logs.

T = one trillion cycles. Polling uses liquid cycles and hysteresis; the total balance may differ. A reported tier is not proof of a completed poll or notification delivery.

Authoritative pricing

Live query
Loading current Event Horizon pricing…

The displayed values are minimum cumulative productive endowments, determined by the backend rather than the browser. Endowed principal remains in Jupiter’s productive stake; recurring maturity-derived ICP payouts enter Event Horizon’s common operating pool and are converted into cycles. Prices can vary monthly with Event Horizon’s retained ICP/XDR observations, and sustained service remains conditional on actual receipts and costs.

02 / Subscribe

Compose the declaration.

Choose a ledger-wide, subaccount, or neuron trigger. The memo is validated continuously against Jupiter Faucet’s complete 32-byte limit.

Subscription memo

Specific targets may be a single value or an inclusive contiguous range. Event Horizon’s displayed backend requirement is authoritative when permanent admission is evaluated.

Generated declaration

A range subscription covers one contiguous inclusive range of specific targets and uses a 2× standard economic basis, regardless of range width.

03 / Principles

Small surface. Clear contract.

Event Horizon adds a prompt signal path without taking ownership of application correctness.

01

Fast path

Canonical ICP is read through its legacy block log; compatible non-ICP ledgers are read through ICRC-3. A global trigger attempts one poke([]) when a poll processes any block.

02

Correctness stays yours

Your canister keeps its own authoritative ledger cursor and a slower independent reconciliation timer. An Index is optional application infrastructure.

03

ICP-funded

A patron productively endows an exact route through Jupiter Faucet. Event Horizon admits it permanently only after a qualifying Faucet payout and complete Historian evidence; recurring payouts, not endowed principal, fund pooled operating cycles.

04

Specific hints win

A non-empty poke reports each retained specific target and its maximum observed qualifying transfer amount; an empty poke reports global-only activity. Both are best-effort hints, and max_amount is not proof of payment. There are no acknowledgements, retries, or delivery guarantees.

Open Source & Verifiable

Event Horizon’s implementation is public and designed for independent verification. Reproduce the production Wasm from a reviewed source revision, then compare its SHA-256 with the module hash installed on the canister.

Also check the canister identity, instance configuration and current controllers. A matching build or the frontend’s reviewed backend-hash registry does not independently establish live controller status.

View source on GitHub Reproduce the build

Designed for Immutability

The backend has immutable instance configuration and no administrative control API. It is designed for eventual finalisation through controller removal after operational acceptance; this is an intended step, not a claim that controllers have already been removed.

Once controller removal is complete, the backend cannot ordinarily be upgraded or reconfigured. The frontend remains separately controlled and can continue to evolve.

Read the trust model Review operational acceptance

Productive Endowment Funding

Patrons can fund subscription declarations through Jupiter Faucet. ICP principal stays in Jupiter’s productive staking path; recurring maturity-derived ICP payouts can eventually reach Event Horizon, which converts retained payouts into pooled operating cycles rather than assigning cycles to individual subscribers.

Endowing principal does not immediately admit a subscription: admission requires a qualifying Faucet payout and Historian evidence. Ongoing operation depends on realised receipts and costs. Perpetual service is an objective, not a guarantee.

Visit Jupiter Faucet Read the subscription guide

Powered by Internet Computer Protocol

The Internet Computer hosts Event Horizon’s backend canister and certified frontend assets. Ledger queries identify relevant activity, canister-to-canister notifications provide best-effort wake-up hints, and cycles converted from ICP pay for operation.

Independent instances can observe compatible non-ICP ledgers, while subscription funding and cycles conversion remain ICP-based. Subscribers still reconcile authoritative Ledger data; notifications are not a delivery guarantee.

Explore the Internet Computer

Open deployment

Additional immutable instances.

Event Horizon’s backend is ledger-generic. Additional immutable instances can be deployed by anyone for compatible ICRC token ledgers. Before final deployment, arrange a dedicated Jupiter Faucet alias through its community review process. Canonical frontend listing is reviewed rather than automatic and requires a verified instance with no controllers.