Switching to a new CRM, ERP, e-commerce platform, or custom app is exciting — until it's time to move the data. Years of customer records, orders, invoices, products, and history live in the old system, often with duplicates, inconsistent formats, missing fields, and custom workarounds nobody documented. If that data moves badly, the new system starts life with the same problems, or worse.
Our legacy data migration services move business data from old systems, spreadsheets, and databases into new ones accurately. We map every field, clean and transform the data, migrate it in tested stages, and reconcile the results — so your team can trust the new system from day one.
What are legacy data migration services? Legacy data migration services move business records from outdated systems — older CRMs, ERPs, accounting tools, custom applications, Access databases, and spreadsheets — into new applications or platforms. The work includes data discovery, field mapping, cleansing and deduplication, transformation to the new system's format, test migrations, final cutover, and reconciliation to prove all records arrived correctly.
Legacy Data Migration at a Glance
Question | Answer |
|---|---|
What it is | Moving records from old systems and spreadsheets into new applications, cleaned and validated |
Core deliverables | Data inventory, field mapping document, cleansing rules, transformation scripts, test migrations, reconciliation reports, cutover plan |
Common sources | Older CRMs and ERPs, legacy custom apps, Microsoft Access, Excel and CSV files, old SQL databases |
Common targets | Salesforce, HubSpot, Zoho, Microsoft Dynamics, NetSuite, Odoo, Shopify, custom applications |
Approach | Iterative test migrations before a final, rehearsed cutover |
Engagement models | Migration assessment, migration project, post-migration cleanup |
Data Migration vs Database Migration vs Cloud Migration
Legacy data migration | Database migration | Cloud data migration | |
|---|---|---|---|
What moves | Business records into a new application | A whole database to a new engine or server | A data estate to a cloud platform |
Main challenge | Mapping and cleaning data for a different data model | Converting schemas and code with minimal downtime | Planning waves, security, and cost |
Example | Old CRM to Salesforce | Oracle to PostgreSQL | On-premise warehouse to Google Cloud |
Codersarts page | This page |
Signs Your Migration Needs Specialist Help
The new system's data model is very different. Fields, objects, and relationships don't map one-to-one.
The old data is messy. Duplicates, free-text fields, inconsistent codes, and missing values.
History matters. You need past orders, invoices, activities, or attachments, not just current records.
Several sources must merge. Data from multiple old systems or spreadsheets goes into one new system.
Go-live dates are fixed. You can't afford a failed or partial migration.
The vendor's import tool isn't enough. Basic CSV imports can't handle relationships and transformations.
Our Legacy Data Migration Services
Data discovery and assessment
We inventory every source, count records, profile quality, and identify the data that must move, can be archived, or can be retired.
Field mapping
We map every source field to the target system, documenting transformations, default values, and business rules, and agree the mapping with your team.
Data cleansing and deduplication
We remove duplicates, standardize formats, fix invalid values, and merge records before migration, so the new system starts clean. For deeper, ongoing cleanup see data quality services.
Transformation and relationship handling
We reshape data into the target model — linking accounts, contacts, orders, products, and activities correctly — using scripts or migration tools rather than manual edits.
Test migrations
We run repeated test migrations into a sandbox, review results with your users, and fix issues before the real cutover.
Cutover
We plan and rehearse the final migration, including a data freeze window and delta loads for records created during the switch.
Reconciliation and validation
We compare record counts, totals, and samples between old and new systems, and share a reconciliation report signed off by your team.
Archiving
We archive historical data that doesn't need to move into a searchable, low-cost store, so nothing is lost.
How It Works
Step 1: Discover
We inventory sources, record volumes, and data quality, and agree what moves.
Step 2: Map
We build and agree the field mapping and transformation rules.
Step 3: Clean
We cleanse and deduplicate source data.
Step 4: Test
We run test migrations into a sandbox and fix issues with your users.
Step 5: Cut over
We perform the final migration during an agreed window, including delta loads.
Step 6: Reconcile and support
We reconcile results, fix any gaps, and support your team after go-live.
What You Get
A data inventory and quality profile of every source
An agreed field mapping document
Clean, deduplicated, transformed data in the new system
Test migration results reviewed by your users
A reconciliation report proving completeness
An archive of historical data that didn't move
Who This Is For
Companies switching CRM | Businesses adopting a new ERP or accounting system | Companies replacing custom legacy apps | Teams leaving spreadsheets |
|---|---|---|---|
Moving to Salesforce, HubSpot, Zoho, or Dynamics | Moving to NetSuite, Odoo, Dynamics, or cloud accounting | Replacing an old in-house system with a modern application | Moving years of spreadsheet records into a proper system |
Why Work With Codersarts
Migrations go wrong when data is moved before it's understood. We profile and map first, clean before moving, test repeatedly with your users, and reconcile every record count. Our team builds the custom scripts and integrations basic import tools can't handle, and can connect the new system to the rest of your stack through our data integration services.
Frequently Asked Questions
What is legacy data migration?
Legacy data migration is moving business records from old systems, databases, or spreadsheets into a new application, with the data mapped, cleaned, and validated along the way.
How long does a data migration take?
Simple migrations from one source can take a couple of weeks. Migrations with several sources, complex relationships, or long history usually take several weeks, including test runs.
How much does data migration cost?
Cost depends on the number of sources, record volumes, data quality, and the complexity of mapping. An assessment provides a fixed quote for the migration.
Can you migrate our historical data?
Yes. We migrate the history you need into the new system and archive the rest in a searchable store, so nothing is lost.
How do you make sure nothing is lost?
We reconcile record counts and totals between old and new systems, review samples with your users, and produce a reconciliation report before sign-off.
Can you clean the data during migration?
Yes. Cleaning and deduplicating before migration is one of the most valuable parts of the project, because the new system starts with trusted data.
What if we have data in several old systems?
We map and merge them into the new system, matching duplicate records across sources. For ongoing consistency across systems, see master data management.
Do you work with the new system's vendor or implementation partner?
Yes. We often handle the data migration while the vendor or partner configures the new system, coordinating on mapping and timelines.
Related Data Services
Data Modernization — modernize the wider data platform
Data Engineering — pipelines and integrations after go-live
Database Design & Architecture — a solid structure for custom applications
Data Readiness Assessment — understand your data before you move it
Ready to Move Your Data Without the Headaches?
Tell us which system you're leaving, where you're going, and when you need to go live. We'll outline the migration plan and what it would take.
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