JavaScript/TypeScript API Integration

iO Associates; Manchester; On-site; GBP 80,000 - 100,000; Full time

Job summary

A leading product consultancy is seeking a JavaScript/TypeScript API Engineer for a 6-month contract in Manchester. This role involves backend API development and integration work within a collaborative and agile team, utilizing modern technologies to enhance a SaaS platform.

Qualifications

• Strong experience in backend JavaScript/TypeScript development.
• Clear understanding of scalable API architecture and third-party integrations.

Responsibilities

• Contribute to backend development and API design using TypeScript.
• Work on system integrations using n8n and other tools.
• Implement robust authentication and access control flows with Permit.io.

Skills

Backend JavaScript/TypeScript development

API design

System integrations

Scalable API architecture

Authentication and access control

Agile environment

Job description

JavaScript/TypeScript API Engineer

Contract Length: 6 Months

Location: Manchester (1 Day a week in Manchester City Centre Office)

Rate: Outside IR35 £350 - £400 per day

*Immediate Start*

Join a fast-moving product consultancy delivering high-impact software for a broad mix of clients across a range of sectors. They're now looking for an experienced contractor to support a critical project focused on API development and complex system integration.

The Role:
You'll be part of a small, highly cooperative engineering team working on a SaaS platform designed to streamline and automate operational workflows. The focus is on building out and refining backend APIs, integrating third-party services, and improving the overall scalability and reliability of the system.

Tech Stack:

• TypeScript & JavaScript

• Node.js with Express

• n8n (workflow and automation integrations)

• PostgreSQL

• Permit.io (RBAC and auth)

• API best practices (rate limiting, downstream HTTP integrations)

• GraphQL (mostly migrating from)

Day-to-Day Responsibilities:

• Contribute to backend development and API design using TypeScript

• Work on system integrations using n8n and other tools

• Collaborate on migrating from GraphQL toward more traditional RESTful architecture

• Implement robust authentication and access control flows with Permit.io

• Help shape and scale API architecture with performance in mind

• Tackle complex business logic in a regulatory or data-driven context

About You:

• Strong experience in backend JavaScript/TypeScript development

• Comfortable in a busy, agile environment

• Confident working autonomously in small, senior teams

• Bonus if you've worked in fintech, regtech, or SaaS products

• Clear understanding of scalable API architecture, auth, and third-party integrations

Please Apply with your CV if this contract is the best fit for you!