In development — early access open Philadelphia, PA / Est. 2025

Legacy software, translated.

Yiwen reads the business software your company still runs on — Access databases, Excel VBA, VB6, classic ASP — and rebuilds it as modern, tested web applications. Same rules. New foundation.

Request early access How it works

Live translation

modInvoice.bas → invoice.ts

' modInvoice.bas — written 2004 Function CalcInvoice(qty As Integer, price As Currency, _ cust As String) As Currency Dim total As Currency total = qty * price If cust = "WHOLESALE" Then total = total * 0.85 End If If qty > 100 Then total = total - 25 CalcInvoice = Round(total * 1.06, 2) ' PA sales tax End Function

// invoice.ts — translated from modInvoice.bas import { round2 } from "./money"; const PA_SALES_TAX = 0.06; export type Customer = "retail" | "wholesale"; export function calcInvoice( qty: number, price: number, customer: Customer, ): number { let total = qty * price; if (customer === "wholesale") total *= 0.85; // R1 if (qty > 100) total -= 25; // R2 return round2(total * (1 + PA_SALES_TAX)); // R3 }

FromMicrosoft AccessExcel VBAVisual Basic 6Classic ASP.NET FrameworkSQL Server 2005

TypeScriptReactPostgreSQL.NET 8REST APIs

01 / The problem

The person who wrote it retired. The software didn’t. Somewhere in your company, a twenty-year-old database still quotes, invoices and schedules — and nobody dares to touch it.

Undocumented rules

Pricing, discounts, tax and approvals live inside macros, forms and modules nobody has read in years.

Rewrites that stall

Starting from scratch means rediscovering every edge case the hard way — usually in production.

Skills that retired

VB6 and Access expertise is disappearing. The software still runs the business.

02 / How it works

Four passes. Nothing lost in translation.

Most rewrites fail on what nobody wrote down. Yiwen makes the old system explain itself before a single new line is written.

01 — Read

Map the whole system first.

Yiwen reads every form, query, macro and module, then builds a dependency map of the entire application — before changing anything.

02 — Specify

Turn hidden logic into plain English.

Business rules are extracted into a readable specification. You confirm what the software actually does — not what someone remembers it doing.

Spec · modInvoice.bas3 rules

R1
Wholesale customers receive 15% off the order total.
R2
Orders above 100 units receive a $25 reduction. Exactly 100 does not qualify.
R3
6% Pennsylvania sales tax applies. Totals round half-to-even to the cent.

StatusApproved by owner

03 — Translate

One model writes. Another checks.

Two independent frontier models work in tandem: one writes against the spec, the other reviews it. Disagreements go to a human — never silently merged.

04 — Verify

Old and new must agree.

Tests are generated from the legacy system’s own behavior. New code ships only when both versions return the same answer — down to the rounding.

$ yiwen verify modInvoice.basparity

✓retail · 10 × $12.50$132.50
✓wholesale · 10 × $12.50$112.62half-even, matches VB6 Round()
✓bulk · 120 × $2.00$227.90
✓boundary · 100 × $2.00$212.00no bulk discount at exactly 100

Legacy ⇄ Modern4/4 agree

03 / What you get

Own your software again.

Modern codebase

TypeScript, React and PostgreSQL — or .NET 8 if you stay on Microsoft. Delivered to your repository.

Living specification

Every business rule in plain English, linked to the exact code that implements it.

Parity test suite

Tests derived from legacy behavior, so every future change stays safe.

Migration report

What moved, what changed, and every decision a human made along the way.

04 / Design principles

Built like infrastructure.

Legacy systems hold a company’s most sensitive logic. We treat them that way.

Your code: Never used to train AI models. Yours before, during and after.
Isolation: Every project runs in its own isolated workspace.
Human gate: Nothing merges without explicit human approval.
Ownership: You own the translated code, the specification and the tests.
Infrastructure: Built on Amazon Web Services and Microsoft Azure.
Headquarters: Philadelphia, Pennsylvania, USA.

05 / Early access

Fluent in legacy.

Early access is opening to a small group of US businesses running Access, Excel VBA, VB6 or classic ASP systems. Tell us what yours does — we’ll tell you what it would take.

Request early access hello@yiwenlabs.com