What to rebuild first when migrating from Bubble

Direct answer

Rebuild the smallest bounded workflow that reduces the most business risk, has clear data ownership, and can run alongside the existing Bubble app.

Do not rebuild the homepage first because it is visible. Do not rebuild the whole database first because it feels foundational. Do not rebuild everything users touch because the client wants to “move off Bubble.” The first migration boundary should prove that custom code can reduce risk without interrupting the business.

Why this matters for Bubble agencies

The first rebuild decision sets the tone for the whole migration. Choose too small a piece and the client sees no meaningful progress. Choose too large a piece and the migration becomes a rewrite disguised as a phase.

Bubble agencies need a way to explain the first phase that is both technically sound and commercially defensible.

A good first rebuild has three qualities:

1. It matters to the business.
2. It has a clear boundary.
3. It can coexist with Bubble.

If one of those is missing, the first phase is probably wrong.

Bad first rebuild candidates

Some parts of a Bubble app are tempting but dangerous first choices.

The entire UI

Rebuilding the UI first often creates visible progress but little risk reduction. The hardest migration problems usually live in data, workflows, permissions, and integrations. A prettier coded interface does not help if the underlying business logic is still ambiguous.

The entire database

A full database migration sounds logical, but it can force every workflow to move at once. Unless the Bubble database is itself the bottleneck, migrating all data first creates a huge coordination problem.

The most complex workflow

The most complex workflow may be important, but it is not always the best first phase. If nobody can specify it clearly, rebuilding it first creates uncertainty. Start with a workflow that is important and understandable.

A low-risk admin feature

This is the opposite problem. It may be easy, but it will not prove the migration strategy. The client needs evidence that the migration reduces real risk.

Good first rebuild candidates

Look for a workflow where custom code creates immediate leverage.

Reporting and analytics

Reporting is often a good first candidate when Bubble searches are slow, dashboards are operationally important, or the client needs historical analysis that Bubble is not well suited for.

A Phoenix reporting layer can read from exported or synchronized data, produce faster queries, and prove value without taking over the entire product.

A critical backend workflow

Some Bubble apps have backend workflows that behave like core infrastructure: invoicing, status changes, inventory updates, matching, notifications, or compliance checks.

If one backend workflow is stable, high-value, and risky to change in Bubble, it may be a strong first Phoenix boundary.

An integration layer

When an app depends on Stripe, HubSpot, Airtable, Shopify, Salesforce, or internal APIs, the integration logic can become a good migration target.

Custom code can centralize API calls, retries, logging, webhooks, and error handling. Bubble can still trigger the integration while Phoenix owns the reliability layer.

Permissions and account structure

If the app has teams, roles, clients, vendors, admins, and complex visibility rules, permissions may become the migration priority.

Be careful: permissions are sensitive. This is a good first candidate only when the rules are well understood and the risk of staying in Bubble is high.

The operational bottleneck

Sometimes the best first rebuild is not the most technical part. It is the part that operations complains about every week: manual review queues, fulfillment dashboards, approval flows, imports, exports, reconciliation, or exception handling.

Operational bottlenecks make strong first phases because the client can feel the improvement quickly.

Use a scoring model

For each candidate workflow, score it from 1 to 5 on these dimensions:

• Business risk if it fails
• Pain caused by current Bubble implementation
• Stability of requirements
• Clarity of data ownership
• Ease of coexistence with Bubble
• Value of custom-code reliability
• Ability to test the workflow

The best first rebuild is not necessarily the highest-risk item. It is the item with high risk reduction and manageable migration complexity.

A workflow with severe pain but unclear requirements may need discovery first. A workflow with clear requirements but low business value may be a poor first phase. A workflow with clear boundaries, moderate-to-high risk, and obvious operational value is usually the sweet spot.

Define the coexistence plan

Before choosing the first rebuild, explain how Bubble and the new system will work together.

Possible coexistence patterns:

• Bubble calls a Phoenix API.
• Phoenix receives webhooks and writes results back to Bubble.
• Phoenix owns a new database table while Bubble displays the result.
• A Phoenix admin tool replaces one Bubble admin page.
• Bubble links users into a Phoenix workflow.
• Phoenix runs background jobs while Bubble remains the front end.

If you cannot describe the coexistence pattern, you have not scoped the first phase clearly enough.

Decide what success means

A first rebuild should have success criteria beyond “it shipped.”

Examples:

• The workflow can be tested automatically.
• The client can trace errors without digging through Bubble workflows.
• A specific report loads under a target time.
• A status change has one source of truth.
• A critical integration retries failures safely.
• A manual operational step is removed.
• A future migration phase becomes easier because the boundary is proven.

These criteria make the migration measurable.

Migration strategy takeaway

The first thing to rebuild from Bubble should not be the flashiest feature or the broadest foundation. It should be the smallest bounded capability that proves the migration strategy.

Pick a workflow that reduces real business risk, has clear data ownership, can coexist with Bubble, and teaches the team how the rest of the migration should proceed. The first phase is not just delivery. It is evidence.