Next.js migration expert — App Router migration, Pages Router to App Router port and Vercel deployment migration from Lovable, Bubble, Base44 or Replit.
Next.js migration expert engagements combine App Router migration, Pages Router to App Router refactors and Vercel deployment migration in one cutover. AI builders trap you: Lovable's GitHub export is one-way, Bubble and Base44 don't export cleanly, Replit Agent's infrastructure isn't portable. We port code and data into a Next.js 16 + Postgres stack on Vercel, keep URLs and sessions intact, and run a zero-downtime cutover. Typical migration: 4 to 6 weeks, $9,999+ fixed price.
Why AI builders ship broken Next.js migration
AI builders optimise for getting to a working prototype. They don't optimise for the day you outgrow the platform. Lovable's chat edits are not reproducible outside Lovable — once you export to GitHub, you can't push changes back. Bubble's visual logic doesn't translate to code at all; escape means rebuild. Base44 wraps Supabase in a proprietary layer; the export dumps raw schemas with no policies. Replit Agent couples your app to Replit's infrastructure — swap hosts and half the integrations break.
The migration itself has four hard parts, and AI-generated code makes each harder. First, data: schemas without migrations, arbitrary UUIDs in the dashboard, and no seed scripts. Second, URLs: AI builders use their own subdomains and internal routing that doesn't map to Next.js file-based routes. Third, auth: sessions signed with a secret that only lives in the AI builder's environment; sign users out and they complain. Fourth, integrations: Stripe webhooks pointing at the old host, OAuth redirects registered to the old domain, cron jobs running on the old infrastructure.
A Next.js migration expert plans all four in parallel. We build the Next.js app from the exported code, introduce Supabase CLI (or Drizzle + Neon/Supabase) migrations backfilled from your current schema, write a redirect map from old URLs to new, issue new session cookies server-side on first visit, and cut DNS over at a planned window. Your paying customers see no interruption. Your URLs still rank in Google. The next engineer you hire can read the code.
Source: Bubble forum — long thread on migration pain out of Bubble
Which AI builder shipped your broken Next.js migration?
The Next.js migration failure mode usually depends on the tool that shipped the code. Find your builder below, then read the matching problem page.
| AI builder | What breaks in Next.js migration | Go to |
|---|---|---|
| Lovable | GitHub export is one-way. Supabase tables ship without RLS. Chat history and prompts are lost. OAuth redirects hard-coded to lovable.app subdomain. | Lovable migrate-out plan → |
| Bolt.new | Code is portable but has no migrations, no tests, and inline secrets. Deployment config non-portable. | Bolt.new rescue → |
| v0 | v0 output is already idiomatic Next.js — the easiest migration. Usually just a backend addition, not a rewrite. | v0 to production → |
| Cursor | Cursor output is standard code; migration is mostly refactoring the architectural debt accumulated across 7+ files. | Cursor refactor → |
| Replit Agent | Infrastructure lock-in: Replit's DB, cron, and object storage don't exist elsewhere. Full rebuild of the backend layer. | Replit escape plan → |
| Claude Code | Already writes to your repo. Migration means imposing architecture across the files Claude touched inconsistently. | Claude Code architecture fix → |
| Windsurf | Portable code; rarely needs migration unless you're leaving Windsurf-specific CI/CD. | Windsurf migration → |
| Base44 | Closed platform. Export dumps Supabase schema raw. Agent handlers rewritten as Next.js Server Actions. | Base44 export plan → |
Anatomy of a Lovable-to-Next.js migration
A B2B SaaS founder reached us 16 months into building on Lovable. Revenue was $22k MRR, two engineers had tried to join, both quit within a week citing 'I can't work with this.' The Lovable GitHub export sat untouched in a repo; the app's source of truth was still Lovable's chat history. Every feature request from a customer triggered a new prompt. Every prompt regressed something. The founder described it in exactly the user-needs vocabulary: 'we're stuck in a loop, prompt, test, break, repeat.'
We scoped the migration as a fixed-price $9,999 platform escape. Week one: we froze Lovable edits, took a fresh GitHub export, introduced Supabase CLI migrations backfilled from the live schema, and stood up a parallel Next.js 16 app on Vercel in a staging subdomain. We mapped every Lovable route to its Next.js App Router equivalent and wrote a redirect map covering the 12 URLs that ranked in Google. Week two: auth. Supabase Auth stayed, but we wired `onAuthStateChange`, fixed the OAuth allowlist for the new domain, and tested every flow against a real email inbox. Week three: integrations. Stripe webhooks repointed to the new URL, idempotency added, subscription state reconciled. Week four: the cutover.
“301 redirects from the legacy URLs carried SEO authority across per Google Search Central's documented handling.”
The cutover window was 22 minutes. Final Supabase data sync (there wasn't much drift because we'd run nightly syncs during build), DNS swap at the registrar, OAuth allowlist updated at Google, Stripe webhook endpoint swapped, sessions re-issued to all logged-in users via a one-time cookie reset (users logged back in once with the same credentials). 301 redirects from the legacy URLs carried SEO authority across per Google Search Central's documented handling. No customer data was lost. The founder could, for the first time, hire engineers who would stay.
Three months later the same app supports a team of four engineers, ships weekly releases, and has zero 'the AI broke working features' incidents — because there's no AI in the write path anymore. The migration was not an escape from Lovable as a product; the founder still uses Lovable for prototyping new UX experiments before porting the approved ones to Next.js. The migration was an escape from the AI-builder-as-source-of-truth architecture.
What a Next.js migration rescue engagement ships
From first diagnostic to production handoff — the explicit steps on every Next.js migration engagement.
- 01
Free rescue diagnostic
Share access to your AI builder project and your target stack preference (Vercel + Supabase is our default). In 24 hours we return a written migration plan with timeline and fixed price.
- 02
Migration design doc
We write a migration doc listing every URL, every integration (Stripe, OAuth, email, analytics), every data model, and the cutover plan. You approve it before code is written.
- 03
Parallel build
We build the Next.js app alongside your live AI-built app. Data syncs run nightly from source to target during the build. Nothing customer-facing changes until cutover.
- 04
Cutover
Planned maintenance window (usually under 30 minutes). Final data sync, DNS swap, OAuth redirect updates, Stripe webhook endpoint update, session re-issuance. Customers log back in once.
- 05
Stabilisation and handoff
Two weeks of monitoring on call. Delivery doc, Loom walkthroughs, runbooks for common ops (deploy, rollback, DB backup). Optional $3,499/mo retainer for ongoing engineering.
Every Next.js migration rescue audit checks
The diagnostic pass on every Next.js migration rescue. Each item takes under 10 minutes; together they cover the patterns that cause 90% of AI-built-app failures.
- 01Current Next.js (or not) baseline
Lovable and Bolt export Next.js code; Bubble and Base44 don't. We map what needs to be ported vs. what needs to be rewritten.
- 02Database portability
Supabase Postgres and Neon are portable. Replit's built-in DB and Base44's proprietary store are not. Escapes from those require a data layer rewrite.
- 03Auth provider carrying over
Supabase Auth and Clerk port cleanly with user IDs preserved. Replit's built-in auth and Base44's wrappers require a provider swap and user migration.
- 04OAuth consent and redirect URIs
We inventory every OAuth provider (Google, GitHub, Apple, Microsoft) and plan the redirect URI update during cutover.
- 05Stripe webhook endpoints
Every Stripe environment (test, live, any custom) has a webhook endpoint we must update atomically at cutover.
- 06Cron and background workers
Lovable and Bolt lack cron primitives; Replit has its own. We replace with Vercel Cron, Inngest, or Trigger.dev at migration time.
- 07Email sender domain and SMTP
Production-quality email requires SPF, DKIM, DMARC on the sending domain. We set these up during migration.
- 08URL structure and SEO
We map every legacy URL and write 301 redirects. Google's guidance confirms 301s carry full authority, usually recovered within days.
- 09Analytics, monitoring, error tracking
We migrate PostHog, Sentry, or equivalents and verify every event fires from the new host.
- 10Environment variable inventory
Full env var map — preview, production, and any custom environments — with secrets identified for rotation during cutover.
Common Next.js migration patterns we fix
These are the shapes AI-generated code arrives in — and the shape we leave behind.
01Lovable edits made via chat. GitHub export is read-only; changes go back into Lovable. No engineer can contribute.01Git is source of truth. Lovable used only for prototyping. Accepted prototypes are ported manually. Regular engineers can work.01Schema edits made in Supabase dashboard with no migrations folder. Staging and production drift. No rollback.01Supabase CLI migrations backfilled from live schema. Future changes go through migrations. Staging reproduces production.01`const API_URL = 'https://myapp.lovable.app'` hardcoded across 15 files. Breaks immediately on cutover.01URL read from env, typed, validated at boot. Deploy-time different per environment.01A background job runs on a Replit-specific cron. Replit-only scheduling; migrates to nothing.01Vercel Cron or Inngest with explicit schedule, logged, monitored, replayable.01Replit Agent's default SQLite. Single-file DB, no backups, no replication, data loss on container restart.01Neon or Supabase Postgres with automated backups, point-in-time recovery, proper connection pooling.01Base44's auth SDK hides Supabase. Export lands with raw RLS disabled and no policies.01Policies written and tested explicitly. Auth wired through Supabase or migrated to Clerk. No opaque layer.01Stripe webhook endpoint pointed at the Lovable preview URL. Events stop firing the moment you cut DNS.01Webhook endpoint updated at cutover, signature secret rotated, event replay verified via Stripe CLI.Next.js migration red flags in AI-built code
If any of these are true in your repo, the rescue is probably worth more than the rewrite.
Fixed-price Next.js migration engagements
No hourly meter. Scope agreed up front, written fix plan, delivered on date.
- turnaround
- Free rescue diagnostic
- scope
- Written migration plan, timeline, and fixed price in 24 hours.
- turnaround
- Deploy to production
- scope
- If your code is already portable, we just need to ship it. Env vars, CI/CD, SSL, monitoring.
- turnaround
- Break the fix loop
- scope
- Architectural refactor plus test coverage before migration. Stops the regression cycle.
- turnaround
- Platform escape
- scope
- Full code and data migration to Next.js + Postgres. Zero downtime, 4-6 weeks.
What Next.js migration rescues actually cost
Anonymized, representative scopes from recent Next.js migration rescues. Every price is the one we actually quoted.
A founder with a clean v0 or Cursor-generated Next.js app that just needs a proper production deploy. Code is portable; the gap is env vars, monitoring, and domain.
- Scope
- Deploy-to-production pass: env vars, CI/CD, SSL, monitoring, rollback plan. No code migration required.
- Duration
- 7 days
A seed-stage team on Bolt.new with a working app in Supabase, but no migrations, no tests, and inline secrets. Code is portable but needs hardening before it's production-safe.
- Scope
- Refactor pass + deploy-to-production. Migrations, tests, secret rotation, env var discipline, monitoring.
- Duration
- 3 weeks
A growth-stage SaaS on Lovable, Bubble, Base44, or Replit Agent. Full platform escape with preserved URLs, users, and paying subscriptions.
- Scope
- Parallel Next.js build, Supabase or Neon migration, auth port, Stripe webhook update, staged cutover, 2 weeks of stabilization.
- Duration
- 4-6 weeks
Migration, or optimize in place?
The honest answer for a surprisingly large share of AI-built apps is: don't migrate yet. If your Lovable or Bolt app has 50 beta users, a 2k-line codebase, and one engineer, migration is premature. Fix the RLS, harden the integrations, and run another 6 months on the platform. Migration costs $5k-$10k and 4-6 weeks; if the app is still proving its market, that capital and time is better spent on product.
Migration makes sense when three signals appear together. First: platform friction is measurable — a developer refused to work on your codebase, your AI builder regresses features weekly, or your AI bill has passed $500/month with no ceiling in sight. Second: revenue or traction justifies it — paying customers with SLAs, investors looking at the code, or enterprise buyers requesting diligence. Third: a feature your platform can't support is on the roadmap — cron, background workers, SOC 2, HIPAA, or region-specific data residency.
If only one or two signals apply, we usually recommend a targeted rescue instead of a migration. A $499 security audit plus a $799 integration fix solves the 80% case for under $1,500 without a platform change. If all three signals apply — and especially if an engineering hire is blocked by the codebase — migration is usually the cheapest long-term option. The diagnostic is free; we'll tell you honestly which bucket you're in.
Some platforms force migration: Replit Agent's infrastructure doesn't exist elsewhere, Base44's proprietary runtime requires a rewrite, and Bubble's visual logic doesn't translate to code. For those, 'stay and optimize' isn't an option — escape is the only path, and the question becomes when, not whether.
Next.js migration runbook and reference material
The documentation, CLIs, and specs we rely on for every Next.js migrationengagement. We cite, we don't improvise.
- Vercel — Next.js deployment
Our default migration target for Next.js apps.
- Supabase CLI — migrations
The migration workflow we install as part of every Supabase-involved migration.
- Drizzle ORM — schema migrations
Our default ORM for migrations off Base44 or Replit where we want vendor-neutral Postgres.
- Google Search Central — 301 redirects
Confirms 301s carry full authority across URL changes.
- Clerk — importing users
The API we use when migrating users off Supabase Auth or Replit's built-in auth.
- Stripe CLI — webhook forwarding
The tool we use to replay webhook events during cutover verification.
- Vercel Cron
The primary replacement for Replit's cron and for scheduling needs in Next.js apps.
Next.js migrationrescues we've shipped
Ported a 12k-line Bolt.new app to Next.js 16 + Supabase in 4 weeks, zero downtime.
Exported Supabase schema, rebuilt auth and agent handlers as Server Actions.
Replaced Replit DB with Neon, rebuilt cron on Vercel, cut hosting cost 60%.
Related Next.js migration specialists
Runs the Vercel deployment migration itself — caching, env vars, edge config.
Most Next.js migration expert engagements keep Supabase as the DB. We fix RLS and migrations in flight.
An App Router migration is the best time to fix half-wired auth. We re-issue sessions cleanly.
Related Next.js migration problems we rescue
GitHub export is one-way. We migrate with zero downtime.
Base44's export is partial. We close the gap.
Replit DB and cron don't exist elsewhere. Here's the replacement.
Sometimes the fix is a full migration. Sometimes it's not. We tell you which.
Next.js migration questions founders ask
Sources cited in this dossier
Your AI builder shipped broken Next.js migration. We ship the fix.
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