Senior Frontend Developer

Role Overview:

*Senior Frontend Developer*

JavaScript

Key Responsibilities:

SDK Architecture & Development:

* Design and build a *lightweight, embeddable JavaScript SDK* for web payments

* Ensure *seamless integration with Angular applications*, including compatibility with Angular lifecycle, zone.js, and change detection

* Develop framework-agnostic APIs usable across *Vanilla JS, Angular, React, Vue*

* Implement secure payment flows (popup, iframe, redirect, modal)

* Ensure backward compatibility and versioning (v1, v2, etc.)

Security & Compliance:

* Implement secure client-side communication (JWT, HMAC, checksum validation)

* Handle *PCI-DSS compliant flows* (no sensitive data leakage)

* Protect against XSS, CSRF, clickjacking, iframe abuse

* Implement tokenization and encrypted payload handling

Performance & Reliability:

* Optimize SDK bundle size, load time, and runtime performance

* Handle async flows, retries, timeouts, and network failures gracefully

* Ensure high availability and resilience across browsers and devices

Browser & Platform Support:

* Ensure compatibility across *Chrome, Safari, Firefox, Edge*

* Support mobile browsers and *Angular-based WebViews*

* Handle popup blockers, iframe restrictions, CSP issues

Developer Experience (DX):

* Design clean, intuitive SDK APIs

* Provide *Angular-specific integration guides, examples, and best practices*

* Write clear SDK documentation, examples, and integration guides

* Support error handling, callbacks, webhooks, and logging

* Create sandbox & production environments

Testing & Quality:

* Write unit, integration, and E2E tests for SDK

* Validate SDK in *Angular applications as well as non-Angular setups*

* Participate in code reviews and architecture discussions

Required Technical Skills:

Core

* *JavaScript (ES6+) Expert*

* *Strong experience with Angular (2+)*

* Deep understanding of *browser internals*

* Strong knowledge of *DOM, events, iframes, postMessage API*

* Experience building *public-facing SDKs or libraries*

SDK & Platform

* Experience with *bundlers* (Webpack, Rollup, Vite)

* Module formats: *UMD, IIFE, ES Modules*

* Versioning and backward compatibility strategies

* CDN-based SDK distribution

Security

* Understanding of *client-side security best practices*

* Experience with *JWT, HMAC, encryption concepts*

* Knowledge of *PCI-DSS*, OWASP Top 10 (frontend)

Testing & Tooling

* Jest / Mocha / Playwright / Cypress

* Browser testing & debugging

* Performance profiling tools

Good to Have:

* Experience in *fintech / payments / checkout flows*

* Experience building *Angular wrappers or services around JS SDKs*

* Knowledge of *Web Components*

* Familiarity with *TypeScript*

* Experience with *React/Vue internals* (bonus)

Experience:

* *4+ years*

* *Must have:* *Hands-on experience building SDKs, JavaScript libraries, or platform-level frontend components*

What Youll Build:

* A *Checkout.js-like SDK*

* Angular-compatible payment SDK integrations

* Secure payment UI (popup/modal/iframe)

* Merchant-friendly APIs

* Scalable, versioned SDK used by thousands of integrations

Khushbu.verma@fiatpayments.com