Senior Full Stack Developer (Next.js / MongoDB) for a health and wellness marketplace

We are looking for a developer who is as good at reviewing code as writing it.

Our team builds with AI assistance and moves fast. Someone has to be the person who checks the work before it reaches the people who depend on us. That is the heart of this role. If your instinct when handed a large branch that passes its tests is "looks good, merge it," this is not your job.

Who we are
Psychable is a US company. We run a directory, marketplace, and education hub in the health and wellness space, connecting individuals with vetted practitioners.

We recently rebuilt our platform from WordPress into a modern Next.js and MongoDB application. The codebase is in genuinely good shape: a layered architecture with dependency rules enforced automatically by tooling, roughly 7,500 tests, and a written decision record behind every significant choice. We are proud of it and we intend to keep it that way.

The shape of the work
This is a part-time, ongoing contract. 10 to 20 hours per week to start, with room to grow. You need a few hours of daily overlap with US Eastern time.

What you will own
The review gate. Review work before it ships. Catch what tests do not: missing indexes, race conditions, authorization gaps, dead code, events that silently record nothing. Say no when the answer is no, and explain why in a way a non-technical teammate can act on.

The live platform. Keep it running, fast, and secure. Own the deploys and the release process.

The architecture. Strict layering, enforced by tooling, currently at zero violations. Your job is to keep that number where it is.

Security. Authentication, sessions, access control, secrets, and dependencies. We treat this as non-negotiable and so should you.

Performance. Measured, not guessed. We want someone who reads a query plan before changing a query.

Our booking marketplace. The biggest project ahead: an individual books and pays for a consult with a practitioner, and the practitioner gets paid. Onboarding, availability, scheduling, payments, payouts, and disputes. Money movement, built carefully and tested to a higher standard than anything else we do.

A payment provider migration. Our subscription processor is changing. The code already isolates the provider behind an adapter, so this is scoped work, not an open-ended rewrite.

Our stack
Next.js 16 (App Router), React 19, TypeScript, MongoDB Atlas, Render, Cloudflare R2, Brevo, Google OAuth and Maps, Vitest.

You must have
Production Next.js, React, and TypeScript. Real applications, not tutorials.

Real MongoDB depth. You can read an execution plan. You know why a case-insensitive regex cannot use an index, and what a partial index will and will not match.

Code review experience. You have reviewed other people's work and caught real problems. You can tell us about a time you blocked something from shipping and why you were right.

Security fundamentals you actually apply: password hashing, session management and revocation, authorization enforced at every layer rather than just in the UI, protecting against account enumeration, and keeping secrets out of the codebase.

Fluency with AI-assisted development, and healthy skepticism of it. We use these tools daily. You should be faster with them and suspicious of their output. Both halves matter.

Respect for an architecture you did not design. You work within the pattern that exists and improve it deliberately, rather than rewriting it to your preference.

Testing discipline. You write tests that would actually fail if the code broke.

Clear, proactive written communication. You report progress and flag problems early without being chased. Most of our team is not technical, so you can explain a risk in plain language.

Nice to have
Payments work: subscriptions, marketplace splits, payouts, disputes, chargeback evidence.

Experience inheriting and stabilizing a codebase someone else built.

Performance work driven by measurement.

Experience in a regulated or sensitive-data industry.

The details
Type: Direct contract, ongoing. No agencies.
Hours: 10 to 20 per week to start, with room to grow
Location: Remote
Reports to: our Chief of Staff
Process: Written application, then a short paid trial for finalists, then a call with our Cheif of Staff and Founder

How to apply (please read)
Applications that skip these questions get passed over.

A scenario. You inherit a branch that is many thousands of lines ahead of production. Most of it was written with heavy AI assistance. The full test suite passes. Nobody has verified any of it in a browser. There is a data migration that has to run before the deploy, and the hosting platform deploys automatically the moment the merge completes.

Walk us through how you would get this to production safely. What would you do first, what would you need to know before you touched anything, and what could go wrong?

2. Tell us about a time you reviewed someone else's code and stopped it from shipping. What did you find, and how did you handle the conversation with the person who wrote it?

3. Describe a security issue you found and fixed in a real project. What was it, how did you find it, and what did you change?

4. How do you use AI tools in your work, and where do you not trust them?

5. You inherit a codebase with an architecture you would not have chosen, but it is consistent and enforced throughout. What do you do?

Tell and show us work you are proud of.