What SaaS tools should you NOT replace with custom software?
Not every SaaS is worth replacing. Payment rails, accounting systems, email infrastructure, compliance-critical tools, and platforms where the vendor's data network is the value carry migration risk that almost always exceeds any licence saving. If replacing it would require rebuilding the vendor's network, certification, or regulatory relationship — not just their software — do not replace it.
Do not replace payment rails
Stripe, GoCardless, Braintree — the compliance cost of replacing them is not worth the licence saving.
Payment processing requires PCI DSS compliance, fraud monitoring, acquiring bank relationships, and ongoing regulatory oversight. Stripe, GoCardless, and Braintree are regulated entities with compliance infrastructure you would need to rebuild from scratch, obtain authorisation for, and maintain under FCA/banking regulations.
Do not replace accounting systems or ERP cores
Xero, Sage, QuickBooks touch too many audit trails and integrations to replace safely.
Your accounting system is the source of truth for legal reporting, tax compliance, payroll, and audit trails. Replacing it requires migrating years of accounting records, re-certifying workflows, and rebuilding every integration — while staying compliant with Making Tax Digital. The saving is not there.
Do not replace tools where the network is the value
LinkedIn Recruiter, aggregator platforms, and compliance-certification tools derive their value from the vendor's network.
LinkedIn Recruiter's value is the 900M+ profile network — not the UI. Job board platforms' value is candidate traffic — not the ATS. Replacing these tools loses the network, which is the thing you are paying for.
Related questions
Depends on what you use. If you use HubSpot primarily as a contact database and deal pipeline, yes. If you use HubSpot Marketing Hub, sequences, ad attribution, and 15+ integrations simultaneously, it is an integrated platform, not a simple CRM.
Sources
- Retool 2026 State of Internal Tools
- PCI DSS v4.0 compliance requirements
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