ERP Integration Services: A Step-by-Step Checklist

Your finance team exports orders from the ERP, your sales team updates the CRM by hand, and someone reconciles UPI settlements in a spreadsheet. The problem is not missing software; it is that ERP integration services were bought as a one-time connector instead of an operating process that survives price changes, GST updates and new sales channels. Founders, finance leads and CTOs at Indian SMBs feel this most when order volume crosses 500-1,000 a month.

What ERP integration services should actually deliver

Most vendors sell 'integration' as a sync between two systems. In practice, a usable ERP integration service covers five things:

• Master data mapping: customer, vendor, item, tax codes, warehouse, price list.
• Transaction flows: quote-to-order, order-to-invoice, invoice-to-payment, PO-to-GRN.
• Reconciliation: daily totals between ERP, gateway, bank and CRM.
• Error handling: retries, dead-letter queue, human-readable alerts.
• Compliance: GST e-invoice and e-way bill fields, TDS deductions, DPDP Act consent and access logs.

Ask for these as line items in the statement of work. If a provider cannot show a reconciliation plan, you will be the one reconciling.

Step 1: Map flows and money before choosing tools

Start with two maps: order-to-cash and procure-to-pay. Write down every handoff where a human copies data. For each handoff, note volume, frequency, currency, tax treatment and failure cost.

Worked example: a Gurgaon distributor doing 1,800 B2B orders a month. Three staff each spend about 90 minutes a day re-entering Shopify and WhatsApp orders into Tally and matching Razorpay settlements. That is roughly 180 hours a month. At an illustrative loaded cost of ₹250/hour, it is ₹45,000 a month. The integration scope: order creation, GST invoice push, payment reconciliation and stock sync. Build estimate: ₹1.8-3.5 lakh one-time, ₹10-18k/month for hosting, monitoring and support. Payback typically lands between 5 and 10 months if order volume holds. These are ranges, not a quote; your tax config and customisations matter.

Step 2: Choose the integration pattern deliberately

Four common patterns:

• Point-to-point API calls: quick, brittle as systems grow.
• iPaaS or middleware: faster to start, recurring licence, limited custom logic.
• Custom middleware: best when GST rules, TDS or pricing logic are specific. Needs ownership.
• Direct database sync: avoid unless vendor-supported; schema changes break silently.

Most Indian SMBs end up with a hybrid: a middleware layer for standard objects and custom services for money flows. Before you commit, review the integration architecture with your CTO or vendor. Ask where the canonical customer ID lives, what happens during a 30-minute ERP outage, and how you roll back a bad batch.

Step 3: Build for failure, test edges, then cut over

An integration that works in a demo fails on the first credit note. Insist on:

• Idempotency keys on every order and invoice to prevent duplicates.
• Retry with exponential backoff, then a dead-letter queue.
• Audit log with request ID, payload hash, user or service account, timestamp.
• Reconciliation report: ERP total vs channel total vs bank or gateway total.
• Secrets in a vault, not in a config file. Role-based access for DPDP.

Test with negative cases: partial payment, overpayment, GST rate change mid-month, customer GSTIN update, cancelled order after invoice, return with credit note. A 100-order test set with at least 15 edge cases is normal. If your provider only tests happy-path order creation, you have not bought ERP integration services; you have bought a demo.

Don't switch off manual entry on day one. Run both systems for 10-15 business days. Each morning, compare three numbers: orders created, invoices posted, payments reconciled. Set thresholds. For example, if unmatched payments exceed 2% of daily volume or ₹25,000, page the owner.

Hosting and observability matter here. A small cloud setup with managed queues, cron health checks and alerting is usually enough; you do not need a data centre. Log retention should match your DPDP and audit needs, often 12-24 months for financial documents. After 30 days, move from daily manual reconciliation to weekly spot checks. Keep a quarterly audit of tax codes, item masters and API versions.

Where to start

If you are evaluating ERP integration services, start with one flow, not five. Pick order-to-invoice or payment reconciliation, map the exceptions, and run a two-week paid discovery before any build. That discovery should produce a data map, error-handling plan, reconciliation format and a fixed quote. Maysan Labs builds these integrations alongside web platforms and internal tools, so the ERP stays the source of truth while your team stops copying between screens.