How to Replace SaaS with Custom Software

Replacing SaaS with custom software is a phased process: audit your current subscriptions, prioritise which to replace, export data, build the replacement, migrate, validate, and decommission the old tools. For UK SMEs spending 30,000 or more per year on SaaS subscriptions, custom software typically pays for itself within two to three years and costs less every year after. The key is replacing the right tools, in the right order, with minimal disruption.

We help UK businesses replace SaaS subscriptions with custom software. This guide covers the general process. For replacing specific platforms, see our guides on Salesforce and HubSpot.

How Do You Audit Your Current SaaS Stack?

Before replacing anything, you need to know what you have and what you actually use:

1. List every subscription: Pull 12 months of credit card and bank statements. Flag every recurring software charge. This is your SaaS inventory.
2. Map usage: For each tool, check the admin console for active users versus paid seats. Note the gap: paid seats minus active users is waste.
3. Assess feature usage: For each tool, identify which features your team actually uses. Most teams use 20 to 40 percent of a SaaS platform's features.
4. Check data export: For each tool, verify that you can export your data in a usable format. This determines how easy migration will be.
5. Calculate annual cost: For each tool, calculate the annual subscription cost, including add-ons and price increase assumptions.
6. Prioritise: Rank tools by annual cost and fit gap (how well the tool matches your needs). High cost plus high fit gap are the top replacement candidates.

Our integration health check can help structure this audit.

Which SaaS Tools Should You Replace First?

Not every SaaS tool should be replaced. The goal is to replace the tools where custom software delivers the most value:

Replace first (high cost, specific to your workflow):

• CRM (Salesforce, HubSpot, Pipedrive): High per-seat cost, central to your sales process, often customised heavily.
• Project management (Asana, Monday.com): If your workflow is non-standard and the tool requires workarounds.
• Help desk (Zendesk): If you need deep integration with your other systems.
• Industry-specific tools: If no standard tool fits your industry workflow.

Keep as SaaS (commodity, well-served):

• Email (Google Workspace, Microsoft 365): Standard, cheap, well-served.
• Video conferencing (Zoom, Teams): Commodity, no advantage in building.
• File storage (Google Drive, OneDrive): Standard, reliable.
• Accounting (Xero, Sage): Specialised, compliance-heavy, better bought.

See our guides on replacing Salesforce, HubSpot, Asana, Zendesk, Pipedrive, Monday.com, Sage, and Xero for specific comparisons.

What Is the Migration Process?

The migration from SaaS to custom software follows a standard process:

1. Discovery (2 to 3 weeks): Map the current SaaS setup: data structures, workflows, integrations, and user roles. Identify which features are used and which are not. Design the replacement system.
2. Core build (6 to 10 weeks): Build the core functionality that replaces the most important features. The goal is a minimum viable system that users can start using.
3. Data export and migration (2 to 4 weeks): Export data from the SaaS platform. Map fields to the new system. Import, validate, and reconcile. This is the most technically complex step.
4. Parallel running (2 to 4 weeks): Run both the old SaaS and the new custom system simultaneously. Users enter data in both systems or the new system only, with the old system as backup. Compare outputs to validate.
5. Advanced features (3 to 6 weeks): Build remaining features, integrations, and reporting that were in the SaaS platform but not in the initial build.
6. Decommission (1 week): Cancel the SaaS subscription. Keep data exports as backup. Train any remaining users.

Total timeline: three to eight months depending on scope. The core system is usable within the first two to three months.

How Do You Handle Data Migration?

Data migration is the highest-risk part of replacing SaaS. The process:

1. Export from SaaS: Use the platform's export functionality to get data in CSV, JSON, or similar format. Some platforms restrict exports or charge for them. If this is the case, it is a lock-in red flag.
2. Data mapping: Map every field from the SaaS export to the new system. Some fields map directly. Others need transformation (different date formats, different field names, merged or split fields).
3. Data cleaning: Remove duplicates, fix formatting issues, fill in missing required fields. Migration is a good time to clean data that has degraded over time.
4. Import: Load the cleaned, mapped data into the new system. This is typically done in batches, with validation after each batch.
5. Validation: Compare record counts, spot-check key records, and verify that relationships are preserved. Any discrepancies are investigated and fixed before proceeding.
6. Parallel running: Keep the old system running with read-only access during the first weeks of the new system. This lets users verify data and catch any migration issues.

For systems with years of historical data, migration is the most time-consuming part of the project. Budget accordingly. See our guide on custom database development for data modelling considerations.

How Do You Manage User Adoption?

Replacing a tool people use daily is a change management challenge:

• Involve users early: Include key users in the discovery phase. They know what features matter and what workarounds they currently use.
• Phased rollout: Move users in batches, not all at once. Start with a pilot group, learn from their feedback, then expand.
• Training: Provide training on the new system before cutover. Focus on how to do the tasks they do daily, not on every feature.
• Support during transition: Provide dedicated support for the first two to four weeks. Quick answers to questions prevent frustration and workarounds.
• Simplicity: Custom software should be simpler than the SaaS it replaces, because it includes only the features you use. This makes adoption easier, not harder.

What Are the Common Pitfalls?

SaaS replacement projects fail for predictable reasons:

• Underestimating data migration: It takes longer than expected. Budget 20 to 30 percent of the project time for migration.
• Feature creep: Trying to replicate every SaaS feature, including ones nobody uses. Build only what is used.
• No parallel running: Cutting over immediately without validation. Always run both systems in parallel first.
• Poor user communication: Users surprised by the change resist it. Communicate early and often.
• Choosing the wrong tool to replace first: Start with the tool that has the highest cost and clearest process gap. Replacing a tool that works well is risky and delivers less value.

See our guide on custom software risks for a full risk framework.

Ready to replace your SaaS subscriptions? Book a free discovery call to discuss your specific situation, or see our services for what we build.