ClarityTTS - Senior Full Stack Developer

Description :

About the job :

Location : Remote globally, preferably in Bangalore.

Start Date : Immediate ASAP

Stack Full-stack : C# .NET (backend) + Vue.js PWA (frontend)

Reporting To : Project Manager

Backend Responsibilities (.NET) :

- Own and build the Interac Reference Code Matcher (B04) the single most critical backend service.

Responsibilities include : Moneris webhook validation (HMAC-SHA256), memo field parsing, regex extraction of reference codes, amount reconciliation (exact, partial, overpayment), three-queue ops routing (UNMATCHED / PARTIAL / OVERPAYMENT), idempotency via moneris_transaction_id, email-parse fallback, force-match and refund admin endpoints, and float account ledger.

- Build the Rate Lock Engine (B02) : fetch XE Currency (CAD-to-USD) and Cargills daily FOREX rates on sender link-open, lock both for 24 hours, compute effective combined CAD-to-LKR rate, enforce expiry and rejection of late payments.

- Build the USDC Settlement Module (B08) : acquire USDC via Circle API, transfer cross-border, liquidate to Cargills USD account, write every event to the blockchain audit ledger.

- Build the Cargills FOREX Account Manager (B09) : route USD for USD requests; trigger FOREX sell to LKR for LKR requests; monitor balances and alert on low thresholds.

- Build the Wallet Balance Service (B10) : maintain per-recipient USD and LKR balances, handle bank transfer and cash pick-up offload routing.

- Build remaining backend services : Payment Link Generator (B01), Flat Fee Calculator (B03), Dual Currency Engine (B05), Sender Confirmation and Delta (B06), Request Status API (B07), Push Notification and Food City Voucher (B11), Bank Deposit Offload (B12).

- Integrate with : XE Currency API, Circle USDC API, Moneris Autodeposit webhook, WhatsApp Business API, Vonage SMS.

- Set up CI/CD pipeline, staging environment, Sentry error monitoring, and Slack alerting for all critical payment events.

- Write unit and load tests for every B04 matching scenario 100% edge case coverage required before staging.

Frontend Responsibilities (Vue.js PWA) :

- Read and understand the existing RoundUp PWA (Vue.js) codebase and component library before building anything new. The SL PWA extends this shell.

- Build all 7 recipient-facing screens : Login/OTP with +94 Sri Lanka prefix (R1), Enter Amount with live USD/LKR toggle and indicative CAD display (R2), Select Sender from contacts (R3), Share Link via WhatsApp / Messenger / Email / copy (R4), Request Status with per-request cards and delta indicator (R5), Wallet Screen showing both USD and LKR balances on one screen with offload actions (R6).

- Build the Sender Landing Page (S1) : rate locks on page load, displays recipient name and receive amount, editable CAD transfer amount with live recalculation, flat fee line, single locked rate line ('CAD 1.00 = USD 0.73' or 'CAD 1.00 = LKR 222.45'), Interac reference code with copy button, rate expiry countdown, I've Sent It button. No login required. Mobile-first.

- Own the PWA setup : service worker, app manifest, offline fallback, add-to-homescreen prompt.

- Own the design system : implement the dark blue fintech theme from the v4 design mockup colour tokens, typography, spacing. No third-party UI kits unless already in the existing codebase.

- Define API contracts with yourself agree the backend and frontend interface before building either side, use mocks during parallel development.

- Achieve Lighthouse mobile score above 90 before pilot launch.

Must-Have Backend :

- 5+ years backend development. Strong C# and .NET you will read and extend PCM CoreService, an existing production .NET API.

- Payments experience : Interac e-Transfer, Moneris Autodeposit, or equivalent Canadian payment rails. You understand how webhooks, idempotency, and reconciliation work in a live payments system.

- Financial reconciliation logic : matching, deduplication, audit trails. You know why double-settlement is catastrophic.

- REST API design and implementation building and consuming multiple external APIs with proper error handling, retry logic, and logging.

- PostgreSQL or SQL Server schema design, migrations, query optimisation.

- Async job queues (Redis, RabbitMQ, or equivalent) webhook processing must never block.

Must-Have Frontend :

- 5+ years frontend development. Strong Vue.js (Vue 2 or Vue 3) you will read and extend an existing Vue PWA not build from scratch.

- PWA development : service workers, app manifest, offline support, add-to-homescreen.

- Mobile-first CSS building for mid-range Android devices on variable connectivity in Sri Lanka.

- Strong eye for UI detail you will implement a specific dark blue fintech design from Figma specs.

- REST API integration consuming endpoints, managing async state, handling loading / error / empty states correctly.

Nice to Have :

- USDC or Circle API experience, or other stablecoin settlement.

- Blockchain audit ledger concepts immutable event logs, on-chain reconciliation.

- Figma design specs are in Figma; ability to implement directly from Figma is a strong plus.

- FINTRAC, PCI-DSS, or financial compliance experience.

- WhatsApp Business API share flows or deep link experience.

- i18n / localisation experience Sinhala and Tamil support is planned post-MVP.

- Fintech or remittance platform background.