Sr. Node.js / TypeScript Engineer - System Migration (Contract)

Remote
Engineering

This is a good fit for someone who enjoys understanding existing systems, figuring out where the edge cases are, and building software that operators can trust to move critical data correctly.

Job description

We're looking for a senior engineer to build a migration service that moves customers from a legacy payments platform into a core platform.

The source system is a legacy PHP application with a SQL database. The target is a set of REST APIs. The work involves understanding the existing data model, mapping it to the new platform, and building a reliable migration service that can be run repeatedly for different partners.

Migration sizes range from a handful of records to hundreds of thousands.

Job requirements

What You'll Be Working On

Reading data directly from a legacy SQL schema
Mapping legacy entities to current API models
Building migration workflows that can start, stop, resume, and retry
Tracking migration progress and failures
Handling large migrations that may run for hours or days
Working through cases where source and target systems don't map cleanly
Integrating with payment, merchant, user, subscription, and token-related data

Some payment data may require access to encrypted values within the source environment before being sent to the destination platform.

Tech Stack

TypeScript / Node.js
SQL
REST APIs
Docker
Kubernetes

What We're Looking For

Strong TypeScript and Node.js experience
Data migration and ETL experience
Seasoned Experience with Docker and Kubernetes in production
Comfortable working directly with relational databases
Experience building backend services and long-running background processes
Good systems design instincts around reliability, observability, and recovery
Able to work through incomplete requirements and messy legacy systems without needing everything specified up front

Bonus Points

Payments or fintech experience
Experience with PHP (in order to reverse engineer any undocumented legacy API interactions)

My information

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Questions

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You're migrating 250,000 merchant records. After 180,000 records have been processed successfully, the destination API begins returning intermittent failures. How would you design the migration process so that it can recover safely without creating duplicates, losing data, or requiring the migration to start over?

During implementation, you discover that a legacy field has no obvious equivalent in the target system. The migration specification does not address this case, and several thousand records are affected. How would you proceed?

Before running the first migration against a customer with 100,000+ records, what specific safeguards, validation checks, and operational tooling would you want in place?

Some payment-related data is stored in an encrypted form within the source environment and must be decrypted before being sent to the destination platform. What controls and safeguards would you put in place to minimize security and operational risk during this process?

A migration completes successfully according to the application logs and no API errors were reported. A week later, a customer reports that some data appears to be missing in the new system. How would you investigate whether the migration introduced a data integrity issue, and what measures would you have put in place beforehand to detect it?

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What are your hourly rate requirements?

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