Web Developer

Heartside Software builds high-impact custom software, ranging from a comprehensive training and certification system to regulated fintech applications and operational SaaS tools. We’re looking for a contract web and mobile developer who can move from a client requirement to a shipped, working feature with minimal hand-holding.

This is integration-heavy, delivery-focused work. You’ll often be the person connecting complex real-world workflows to third-party APIs and data sources, building the web and mobile front ends that power them. Whether you’re enhancing user workflows, integrating payment rails for fintech clients, or bringing older platforms up to current best practices, you’ll work across concurrent projects, where the ability to context-switch and communicate clearly matters as much as raw coding ability.

What you’ll work on

Recent and representative projects include:

• Payment & fintech platforms - e.g. a card-to-crypto payment processing platform routing payments through an on/off-ramp provider into non-custodial wallets, with Stripe-modeled API design and POS/compliance integrations.
• Client-facing web apps and PWAs - responsive, installable progressive web apps (Next.js) for service businesses, built to real scoped estimates and delivered to a client.
• Third-party integrations - connecting platforms like POS systems, payment providers, compliance systems, time-tracking, and issue-tracking tools via REST APIs, webhooks, and OAuth.
• Automation & internal tooling - data pipelines and workflow automation that reduce manual effort for clients and the internal team.

Responsibilities

• Build and ship web front ends and mobile-first / PWA experiences from client requirements and estimates.
• Design and implement integrations against third-party REST APIs (payments, POS, SaaS platforms), including auth, webhooks, and the server-side glue needed to work around browser constraints (e.g. CORS proxies).
• Write clean, maintainable code and own your features end to end - from local setup through deployment.
• Collaborate with project leads and communicate progress, blockers, and trade-offs clearly to a technical lead and, at times, directly to clients.
• Help scope and estimate work where relevant, and flag risks early.

• Strong professional experience building modern web applications with React / Next.js and TypeScript / JavaScript.
• Solid grasp of mobile-first, responsive UI and PWA development (installable apps, offline considerations, service workers).
• Demonstrated experience integrating third-party REST APIs - auth flows, webhooks, pagination, error handling.
• Comfort writing server-side / backend code (Node.js) to support front ends, including proxying and data transformation.
• Working knowledge of SQL and relational data.
• Proficient with Git and comfortable working across macOS and Windows environments.
• Self-directed: able to take an ambiguous requirement, ask the right questions, and deliver.
• Experience with complex software project management and CRM architecture, including managing technical documentation and stack-wide implementation.

Nice to have

• Expertise in one of the following areas: Cloud Infrastructure, Security, iOS/Android mobile apps, or embedded/IoT
• Experience integrating industry-specific platforms - POS systems, compliance systems, or other regulated-industry tooling.
• Payments / fintech experience - Stripe or Stripe-style API design, and/or crypto payment rails (USDC, non-custodial wallets, on/off-ramp providers).
• Cross-platform native mobile (React Native or similar) for cases that go beyond a PWA.
• Workflow automation experience - Power Automate / low-code tools, scripting, and database-to-tool pipelines.
• Familiarity with AI-assisted development workflows (e.g. Claude Code) and building internal skills/tooling.
• Consulting or agency background - comfortable with multiple concurrent clients and client-facing communication.