Senior TypeScript/Next.js Backend Developer — Production SaaS (PostgreSQL, External API Integrations)
Budget: £18 – £36 GBP
We are hiring an experienced backend-focused full-stack developer to work on a live, production SaaS platform. The platform handles complex, regulated workflows with multiple external API integrations — both REST and SOAP-based, including certificate-authenticated and OAuth2-secured endpoints.
This is not a startup greenfield project. The platform is already in production. You will be working inside an existing codebase with real users, not building from scratch.
What you'll be working on:
• Migrating a legacy database abstraction layer to native postgres.js (incremental, tested, phased — not a big-bang rewrite)
• Adding a PostgreSQL-backed background job worker to handle long-running external API calls asynchronously
• Hardening workflow state management — ensuring all status transitions are guarded and audited centrally
• Structured logging improvements (pino is already set up)
• Supporting and extending external REST/SOAP API integrations
• Backend improvements to document processing and confidence-scoring features
• Admin/operator tooling — queues, dashboards, review surfaces
Required skills — must have in production, not just tutorials:
• TypeScript — strict mode, Zod validation, discriminated unions
• Next.js 14 App Router — Route Handlers, Server Components, auth patterns
• PostgreSQL — schema design, transactions, migrations, partial indexes, concurrency
• postgres.js — native tagged template API
• External API integration — SOAP/XML, OAuth2 machine-to-machine, or certificate-based APIs
• Async backend patterns — idempotency, retry/backoff, dead-letter handling
Strongly preferred: Background in regulated or compliance-critical software; SOAP/XML signing experience; pg-boss or BullMQ; structured observability (pino/OpenTelemetry); multi-jurisdiction integration architecture
What you must NOT do without written approval: redesign the stack, introduce ORMs (no Prisma/Drizzle), change workflow lifecycle semantics, alter submission payload structures, modify auth or certificate handling, rewrite working modules
Deliverable format: Git PR per task with clear commit history. Per-task technical note: what changed, why, migration impact, rollback plan, test coverage, known limits. For API work: request/response mapping, retry behaviour, error cases handled.
To apply, include:
1. 2–4 projects that are directly comparable — stack, your role, production scale
2. Specific experience with Next.js App Router backend development
3. How you approach idempotency in external API submission pipelines
4. One example of a risky production refactor you shipped safely, with the risk you managed
5. Your timezone and weekly availability
If you have worked in regulated, auditable, or compliance-critical backend systems and understand what it means when bugs have financial consequences — we want to hear from you first.
This is not a startup greenfield project. The platform is already in production. You will be working inside an existing codebase with real users, not building from scratch.
What you'll be working on:
• Migrating a legacy database abstraction layer to native postgres.js (incremental, tested, phased — not a big-bang rewrite)
• Adding a PostgreSQL-backed background job worker to handle long-running external API calls asynchronously
• Hardening workflow state management — ensuring all status transitions are guarded and audited centrally
• Structured logging improvements (pino is already set up)
• Supporting and extending external REST/SOAP API integrations
• Backend improvements to document processing and confidence-scoring features
• Admin/operator tooling — queues, dashboards, review surfaces
Required skills — must have in production, not just tutorials:
• TypeScript — strict mode, Zod validation, discriminated unions
• Next.js 14 App Router — Route Handlers, Server Components, auth patterns
• PostgreSQL — schema design, transactions, migrations, partial indexes, concurrency
• postgres.js — native tagged template API
• External API integration — SOAP/XML, OAuth2 machine-to-machine, or certificate-based APIs
• Async backend patterns — idempotency, retry/backoff, dead-letter handling
Strongly preferred: Background in regulated or compliance-critical software; SOAP/XML signing experience; pg-boss or BullMQ; structured observability (pino/OpenTelemetry); multi-jurisdiction integration architecture
What you must NOT do without written approval: redesign the stack, introduce ORMs (no Prisma/Drizzle), change workflow lifecycle semantics, alter submission payload structures, modify auth or certificate handling, rewrite working modules
Deliverable format: Git PR per task with clear commit history. Per-task technical note: what changed, why, migration impact, rollback plan, test coverage, known limits. For API work: request/response mapping, retry behaviour, error cases handled.
To apply, include:
1. 2–4 projects that are directly comparable — stack, your role, production scale
2. Specific experience with Next.js App Router backend development
3. How you approach idempotency in external API submission pipelines
4. One example of a risky production refactor you shipped safely, with the risk you managed
5. Your timezone and weekly availability
If you have worked in regulated, auditable, or compliance-critical backend systems and understand what it means when bugs have financial consequences — we want to hear from you first.
Related categories:
Node.js
PostgreSQL
Typescript
Backend Development
API Integration
Next.js
SOAP API
REST API