Idempotent · ordered · conflict-awarev2 engine

Two-way invoice sync that survives the real world.

LedgerBridge keeps internal invoicing and QuickBooks Online in lockstep — tolerant of duplicate events, out-of-order delivery, write conflicts and partial failures. Every event is observable, replayable and audited.

Live sync

Watch an invoice cross the bridge

An event leaves your internal system, lands in the durable outbox, is mapped and applied to QuickBooks — exactly once.

Internal invoicing
INV-20296source
Globex Corp$84,205.18
Queued
outbox
QuickBooks Online
INV-20296Queued
Globex Corp$84,205.18
Architecture

A durable pipe between two ledgers

Every write goes through a durable outbox and a single leased worker, so duplicate and out-of-order events can never double-apply.

Ingest
Internal invoicing emits invoice events over webhooks.
Durable outbox + leased worker
Append-only, deduped by event key. A single leased worker drains it in order.
Map
Conflict-resolve
Apply
QuickBooks Online
Writes land exactly once; reads reconcile back upstream.
Periodic reconcilerevery 5 min
Field-level diff against QBO catches missed webhooks and silent drift — opening a conflict only on true divergence.
Reliability

Calm under partial failure

Idempotency

Duplicate and replayed events collapse to a single QBO mutation, keyed by event ID — no double-billing, ever.

Conflict resolution

Last-writer-wins by default, with a flag when both sides truly diverge — surfaced field-by-field for a one-click call.

Retries + dead-letter

Exponential backoff on transient failures, then a replayable dead-letter queue. Nothing is silently dropped.

Auditability

Every state transition — automated or human — is recorded with actor, before/after and correlation ID.

Built on a boring, durable stack
Next.js 16 TypeScript Tailwind v4 shadcn/ui Postgres outbox QuickBooks API

Put your invoice sync on solid ground.

Open the operational dashboard, or read the source. Everything runs on mock data out of the box.