Independent guide

Online Business Due Diligence Checklist

Due diligence is the process of testing whether the business you think you are buying is the business that actually exists.

Updated September 14, 2026Educational research
Affiliate disclosure: Some Flippa links on this page are referral links. If you use one and later complete qualifying activity, we may earn a commission. Digital Deal Compass is independent and is not Flippa.

Start with the investment case

Write the reasons you believe the business is attractive and the assumptions each reason depends on. Diligence should try to disprove those assumptions, not merely collect documents.

Financial diligence

  • Reconcile revenue to source systems and payment records.
  • Review recurring versus one-time revenue.
  • Normalize owner expenses and challenge add-backs.
  • Identify working-capital, inventory and capital-expenditure needs.
  • Check refunds, chargebacks, discounts and taxes.
Want to see what is currently for sale?

Use the live marketplace to compare real listings against the criteria in this guide.

Browse Flippa ↗

Commercial and customer diligence

  • Measure customer concentration and churn.
  • Review acquisition channels and payback assumptions.
  • Inspect pricing history and discount dependence.
  • Check contracts, renewal terms and cancellation rights.

Traffic and marketing diligence

Validate analytics ownership and historical consistency. Segment traffic by channel, geography and landing page. For SEO businesses, inspect branded versus non-branded demand, page concentration and link risk. For paid acquisition, verify spend, attribution and contribution margin.

Operations and technology diligence

Map owner tasks, contractors, software, suppliers, code repositories, deployment processes and support burden. Look for undocumented knowledge that would disappear when the seller leaves.

Legal, ownership and transfer diligence

Confirm ownership of domains, code, trademarks, content and customer data. Review material contracts, licenses and third-party platform rules. Build a transfer schedule before signing so both sides know exactly what changes hands.

Explore Flippa ↗