Express.js consultant for teams considering a framework move
Written audit plus migration plan to NestJS or Fastify. Hours, risks, rollback path. Optional implementation follow-up.
Who this is for
Engineering leader on a legacy Express API thinking about migrating to NestJS or Fastify.
The pain today
- Nobody has estimated the migration cost in writing.
- Risk appetite is low; leadership wants a plan first.
- Team is split between 'stay and harden' and 'rewrite now'.
- The last contractor tried a migration and abandoned it halfway.
The outcome you get
- A written Express audit plus migration plan.
- Hours, risks, rollback decisions per phase.
- A refactor-vs-rewrite recommendation with the math to back it.
- Optional implementation follow-up.
What the audit covers
The Express audit reads the full routing layer, middleware stack, error handling, database access pattern, testing coverage, and deploy pipeline. The written report covers: middleware inventory (which are library, which are custom, which are load-bearing), route complexity distribution (how many routes handle real business logic vs pass-throughs), database query hot spots, authentication consistency, testing coverage on the critical path, and security posture (helmet, rate limiting, CORS). Each finding gets severity and hours-to-fix. The migration section answers 'if we move, where do we move first'.
When to migrate and when not to
Rough guideline: under 20 endpoints, fewer than 3 engineers, domain not expected to grow — stay on Express, harden, write tests. Above 20 endpoints, more than 3 engineers, or growing fast — NestJS or Fastify pay off inside 12 months. The audit measures both scenarios against 24 months of carrying cost. About 60% of the audits I run for Express services recommend migration; about 40% recommend staying and hardening. Both are legitimate answers.
Sample Express-to-NestJS migration plan
Four phases. Phase 1 (1 to 2 weeks): add NestJS as a dependency, mount under the existing Express app, migrate one leaf route as proof. Phase 2 (3 to 6 weeks): migrate middleware (auth, logging, error handling) into NestJS guards and interceptors; move routes domain by domain. Phase 3 (2 to 4 weeks): migrate the business logic into NestJS services and providers with proper DI. Phase 4 (1 to 2 weeks): remove the Express host, flip CI/CD, retire the old deploy. Total: 7 to 14 weeks for a mid-size service.
Pricing and deliverable
Advisory engagement at $4,500 per month (pro-rated for 1 to 4 week scope). You get a written audit, a migration plan (or hardening plan), a 60-minute debrief call, and a follow-up two weeks later. If you want me to execute, the Applications subscription at $3,499 per month covers implementation. Handing the plan to another engineer is fine — the document is the product.
Recent proof
A comparable engagement, delivered and documented.
Unified payment orchestration across Asia and Europe
Delivered the payment orchestration platform at bolttech, a $1B+ unicorn, with 40+ integrations across multiple regions.
Frequently asked questions
The questions prospects ask before they book.
- Express or Fastify — which migration is cheaper?
- Fastify is cheaper (closer API shape, less code change). NestJS is more work but delivers more structure. The audit picks the right target based on team preference and domain complexity.
- How long does the audit take?
- 1 to 3 weeks for Express services (usually smaller than NestJS codebases by volume). Longer for services with no tests and no documentation.
- What if the team cannot agree?
- The audit exists to break that tie. The written recommendation is framed in business cost (engineer hours, uptime risk, feature velocity over 24 months) so the team can disagree with the math, not with the opinion.
- Do you help estimate staffing?
- Yes. The plan includes staffing suggestions — one senior plus one mid for most migrations, two seniors for larger ones. Hiring is your call; I give the size.
- Can you stay on after the audit?
- Yes. Fractional CTO retainer at $4,500 per month if advisory continues. Applications subscription at $3,499 per month if you want hands-on execution.
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