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Migration guide

How to Migrate From a Legacy In-House ERP to Apragya Without Losing the Rules Your Team Built

For owners, finance heads and IT leads running a home-grown system: move masters, open balances and working rules across at a period start, with a parallel run before you let go.

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An IT lead moving coloured folders from an old cabinet into a new tray beside an old server

To migrate from a legacy in-house ERP, you first have to find out what it actually does. A system written ten or fifteen years ago by one developer, or a small local vendor, usually holds rules that nobody has written down: a discount that applies to one distributor, an approval that only fires above a limit, a stock report the owner reads every morning.

The data is the easy part. Tables can be queried and exported. The hard part is that the people who built the system may have moved on, the database has fields nobody uses, and every month end depends on a report that somebody wrote in a hurry.

This guide gives the order of work, an illustrative move at a Coimbatore pump maker, and how Apragya takes the data and the rules across.

How to migrate from a legacy in-house ERP, in order

Start with a rule inventory, not the data. Sit with the people who use the system daily and list every report, approval, numbering series, discount and stock rule it applies. Anything missed here turns up as a surprise during the parallel run.

Then choose a cut-over at the start of a month, and ideally a quarter or financial year, so GST returns and payroll are not split across two systems. Export in dependency order: accounts before parties, parties before open invoices, items before stock.

Finally, prove it. Agree the opening trial balance, debtors, creditors and stock quantities between the two systems before anyone stops entering in the old one.

  1. List rules and reports the old system enforces.
  2. Fix the cut-over date at a period start.
  3. Export and clean masters: accounts, parties, items, employees.
  4. Import opening balances, stock and open invoices and bills.
  5. Run a parallel month and agree the totals.
  6. Freeze the old system as read-only history.

What staying on a home-grown system costs

One person holds the keys

Changes wait for the only developer who understands the code.

Compliance catches up late

Every GST or payroll change is a new piece of custom work.

Data nobody trusts

Duplicate parties and unused fields make every report a debate.

Month end by hand

Figures are copied out to spreadsheets to finish the close.

An illustrative move at a Coimbatore pump maker

Take an illustrative 140-person pump and motor manufacturer whose ERP was built in-house on a SQL database. It handled orders, stock and accounts, but payroll sat in a separate package and the e-way bill was prepared by hand on the portal.

From an old database to working books

  1. Rules listed

    Every report, approval and special price written down.

  2. Data exported

    Masters and open items queried out as files.

  3. Cleaned

    Duplicate parties merged, dead items dropped.

  4. Imported

    Accounts, parties, items and opening stock loaded.

  5. Parallel month

    Both systems run; totals compared weekly.

Listing the rules first is what kept the parallel month short.

The rule list found eleven things the old system did quietly, including a credit hold for two dealers. Nine became settings in Apragya, two were retired. The parallel month closed with debtors, creditors and stock agreeing, and the old server was switched to read-only.

Eleven tokens, nine placed in a new box and two set aside
Nine of the old system's hidden rules became settings. Two were retired on purpose.

How the move works in Apragya

Step 1 of 5

Rule inventory

List reports, approvals, prices and numbering the old system enforces.

  1. Rule inventory: List reports, approvals, prices and numbering the old system enforces.
  2. Export: Query masters and open documents out to CSV or Excel files.
  3. Preview and map: Check each file's columns against Apragya fields before loading.
  4. Load in order: Accounts, parties, items, opening stock, then open invoices and bills.
  5. Agree and cut over: Match the trial balance and stock, then stop entries in the old system.

Replacing custom ERP software with configured software

A custom system fits the business it was built for, on the day it was built. A configured platform lets an admin change approvals, fields and numbering without code, and statutory updates arrive with the product rather than as a project.

Home-grown ERP, against Apragya

FeatureIn-house ERPApragya
Changing a ruleCode change and a releaseA setting changed by an admin
GST and e-invoiceBuilt and maintained by youGSTIN checks, IRN, e-way bill included
PayrollOften a separate packagePayroll with PF, ESI, PT and TDS on the same employee
Access controlScreen by screen, if at allRole-based down to sub-features
Audit trailDepends on what was builtWho did what, on which record, and when

Checked against public information on 16 September 2026.

What sets Apragya apart for a legacy ERP migration

One record across apps

Sales, stores, accounts and HR read the same party and item.

Rules as configuration

Approvals, fields and numbering are set, not coded.

Reach old systems

The Tenant Runner reaches on-premise databases over an outbound link.

AI agents on records

Agents run on events and save their output on the record, with review.

Audit log

User, role, action, record, time and IP, with a tamper check.

Multi-company

Each entity in the old system keeps its own books.

Start the structure with chart of accounts import and opening invoices, and weigh the effort in build vs buy for business software.

Getting started with a legacy ERP migration

  1. Write down every report, approval and special rule the old system runs.
  2. Pick a month or year start as the cut-over date.
  3. Export masters and clean duplicates before importing.
  4. Load structure, then opening stock and open items, and agree totals.
  5. Run one month in parallel, then make the old system read-only.

Keep the old database readable for at least one audit cycle. Nobody should have to rebuild history to answer a question.

What it costs to start

Free
Up to 3 users
CRM, HR and Vendor Onboarding
INR 3,999
Starter, a month
Up to 10 users, CRM and HR plus a choice of apps
INR 7,999
Pro, a month
Up to 25 users and every enterprise app

Migrating from an in-house ERP, answered

Can Apragya read our old database directly?
If it is PostgreSQL, the Postgres connector can query it, and the Tenant Runner can reach it inside your network. For other databases, export to CSV or Excel and import.
Should we move all the history?
Usually not. Move masters, open items and opening balances, and keep the old system readable for history.
What if our old system had custom rules?
List them first. Most approvals, fields and numbering rules become settings; the rest can often be handled by an AI agent or retired.
How long should the parallel run be?
One full month is common, long enough to include a month end and a GST return.
What does it cost to start?
The free plan covers up to 3 users with CRM, HR and Vendor Onboarding and 1,000 AI Credits a month. Starter is INR 3,999 a month for up to 10 users, with CRM and HR plus a choice of apps such as Sales and POS, Inventory, Payroll, Purchase and Payables, Support and Manufacturing. Pro is INR 7,999 a month for up to 25 users with every enterprise app, including Finance and Accounting, plus 5,000 AI Credits, single sign-on and audit logs.

Retire the old server on your terms

List the rules, pick a period start and run a month in parallel.

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