Accounting & Invoicing Planner

The problem

When people ask a coding agent for a bookkeeping or invoicing app with a short prompt, the agent often adds a full general ledger, a balance sheet, a bank reconciliation screen and a payroll module. Nobody asked for them, and they do not work. The agent adds them because it has no reliable picture of what real accounting and invoicing tools ship. The app looks like a finance suite, fails on first use and takes weeks to untangle.

The opposite also happens. The agent delivers a toy: three hardcoded numbers labelled "P&L report", reconciliation as a single checkbox, and invoice PDFs whose numbering resets every time the server restarts. Neither result is something you can sell or use.

What it is built from

The planner is based on a count across 37 sources: 15 live SaaS products (QuickBooks, Xero, Zoho Books, FreshBooks, Wave, Sage 50, Odoo, Manager.io, Invoice Ninja and others), 12 marketplace and template products, and 10 open-source codebases. Every feature in the planner carries a reference such as "INV-A06 income and expense ledger: 31/37 sources" or "INV-A12 bank reconciliation: 24/37 sources". Each reference links to a table that lists the exact products counted.

A coding agent cannot state that an income and expense ledger appears in 31 of 37 reviewed products unless it repeats the whole review. It also would not know that bank reconciliation is a dedicated matching screen in Xero, QuickBooks, Zoho and FreeAgent, and that a checkbox does not do the job. The counts, the source IDs, the decision rules and the known failures are in this package. They are not in a model's training data.

Seven of the reviewed products were also opened in a browser and screenshotted during the research: InvoiceX, Smart Billing, Kanakku, ViserBill, Mint Invoice, Express Invoice and m'Manager. This gave direct evidence of their screens and workflows, in addition to the 37-source count. (These are competitor products we studied. They are separate from the live demos further down the page, which are apps built from this planner.)

Penny, the top-ranked of the seven builds: true double-entry, reconciliation and P&L. You can log into it from the demos below.

What you get

A package of five files that your coding agent reads and acts on:

• START-HERE.md: the entry point. You give one instruction, "Read START-HERE.md and follow it." The agent then runs a structured set of discovery questions before it writes any code.
• skill.md: the core of the planner. It has 11 operating rules, 6 discovery blocks, 4 scope presets (Basic Bookkeeping, Basic Bookkeeping + Invoicing, Moderate Accounting Operations, Advanced Platform), a scan that catches feature groups you chose to leave out (the forbidden-family scan), and an output format for the spec with 21 sections.
• evidence-summary.md: short references (INV-A01 through INV-A30, pain points, workflows, failure modes, technical rules, UI patterns) that the agent keeps in context while it plans.
• example-output.md: a worked build spec that shows what the planner produces.
• BUYER-README.md: a usage guide, scope warnings and what support to expect.

The build spec your agent produces contains: locked decisions, a list of what is out of scope, a scope table with its evidence, the data model, a screen map, workflows, technical requirements, security and compliance notes, reports, a step-by-step build sequence (7-9 steps for Basic), acceptance tests, and a final handover check that must include the result of the forbidden-family scan.

Tested in a build-off

Three coding models built seven working accounting and invoicing apps from this planner: Claude Opus 4.8 in four build runs, GPT-5.5 in two, and Gemini 3.5 Flash. All seven run as live demos you can log into from this page, and the full audited ranking is published as a PlanSmith benchmark.

What it covers

The planner asks its questions in six blocks:

1. Business shape and the Basic path: bookkeeping only, or bookkeeping with invoicing; business size; the kind of product you are building.
2. Roles and the workflow that matters most: owner/admin, bookkeeper, accountant/advisor, staff submitter, client portal user, finance approver.
3. Core finance loop: income/expense entry, cash/bank accounts, vendors/payees, receipt attachments, invoice builder, manual payment recording, receivables dashboard, reports.
4. Optional branches and limits: quotes, recurring transactions, vendor bills/AP, bank statement import, bank reconciliation, full double-entry/GL, balance sheet/trial balance, tax/VAT/GST, online payment gateway, customer portal, multi-currency, projects/time, inventory/POS sync, payroll, multi-business/SaaS, OCR. If you select any of these at the Basic depth, the planner checks whether the scope should be trimmed.
5. Policies and local rules: country/currency, accounting depth, payment method, tax handling, existing data to import, local reporting or numbering rules.
6. Stack, hosting, UI priority, visual direction and Build Execution Mode (Guided Step / Batch / Autopilot).