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In progressAccounting & finance automation

KarbonCopy

The whole accounting practice, on your own network.

A self-hosted practice-management system for accounting firms — work tracking, clients, time, billing, a client portal, e-signatures and a compliance calendar — that runs on one machine in the office instead of a vendor's cloud. Because it lives on the firm's network, it can watch the file server and react the moment a finished return lands.

View source on GitHub
Database tables
43
MCP tools
33
App pages
34
Lines of TypeScript
41.5k
karboncopy — illustration

Waiting on client

Acme Holdings · 1120-S
Northwind LLC · 1065

In prep

Bluebird Trust · 1041
J. Sample · 1040

Review

Contoso Inc · 1120

Ready to sign

Fabrikam Co · 1065
File server: “Contoso_2025_1120_final.pdf” landed → linked to job, client notified

Two ways to read it

In plain English

A self-hosted practice-management system for accounting firms — work tracking, clients, time, billing, a client portal, e-signatures and a compliance calendar — that runs on one machine in the office instead of a vendor's cloud. Because it lives on the firm's network, it can watch the file server and react the moment a finished return lands.

For engineers

A single-process Next.js 15 (React 19) app with a custom server that also hosts Socket.IO realtime, a UNC-aware chokidar file watcher, a scheduler and an IMAP poller. SQLite via Drizzle (43 tables), scrypt cookie auth, 5-tier RBAC, AES-256-GCM encryption of tax IDs at rest, Stripe checkout, on-prem e-signature with a tamper-evident audit chain, a REST API and a 33-tool MCP server on one service layer.

What it does.

  • Live file-server watcher that links finished returns to clients and jobs
  • Work Kanban and a compliance calendar generated from entity type and fiscal year
  • Billing from WIP, Stripe payments and a secure client portal
  • On-prem e-signature with a tamper-evident audit trail
  • Books-health radar: duplicate payments, backdated entries, round-dollar plugs
  • Built-in 33-tool MCP server so Claude can run the practice

The story

Cloud practice tools can't see the office

Karbon, Canopy and TaxDome are good products, but they live in someone else's data center. They can't notice that a return just landed on the firm's file server, can't read documents on-premises, and can't reach QuickBooks Desktop or tax software running on the same LAN. KarbonCopy can — and it hands all of it to Claude through a built-in MCP server.

Built with

  • TypeScript
  • Next.js 15
  • React 19
  • SQLite
  • Drizzle ORM
  • Socket.IO
  • shadcn/ui
  • Stripe
  • pdf-lib
  • MCP SDK

Status: In progress · started June 2026 · open on GitHub

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