Senior Backend Engineer (Integrations & APIs)

**Location: Hybrid — Curitiba, Brazil (1–2 days/week on\-site)** **Type: Contract (PJ)** **Salary: $2800 \- $3800 (Depending on experience and English fluency)** **Schedule: Must be available to work US hours (Mountain Standard Time \- MST)** **About WAVV** WAVV is an innovative integrated dialer solution designed to enhance the efficiency of modern outbound revenue teams. Our multi\-line power dialer seamlessly integrates with CRMs, enabling teams to triple call volumes without fatigue or risking spam flags. Offering features like real\-time spam protection, dedicated local numbers for higher answer rates, and unlimited calls, WAVV optimizes outbound communication. Plug\-and\-play integration ensures effortless adoption, empowering teams to focus on meaningful conversations and closing deals. At WAVV, we believe great conversations drive growth, and our mission is to help teams dial smarter, not harder. **What you’ll do** * Design and implement OAuth 2\.0 authentication flows (auth code, refresh tokens, scopes) * Build bi\-directional REST API integrations between CRMs and internal systems * Ensure data syncing is reliable, queued, retry\-safe, and resilient to failures * Handle webhooks, rate limits, pagination, and API versioning * Monitor and debug integration health, edge cases, and data consistency issues * Prepare integrations for app store reviews and platform compliance requirements **What we’re looking for** * Strong backend experience (ideally Node.js or a similar async environment) * Deep understanding of REST APIs (designing, consuming, rate limits, authentication flows) * Hands\-on experience with OAuth 2\.0 and token lifecycle management * Experience integrating with third\-party APIs, including major CRM platforms (HubSpot, GoHighLevel, Salesforce, etc.) * Comfortable working with JSON, webhooks, and event\-driven systems * Experience with async processing and queues (BullMQ, SQS, RabbitMQ, etc.) * Solid understanding of retries, idempotency, and data consistency * Ability to design and maintain reliable sync pipelines * Strong debugging and problem\-solving skills **Nice to have** * Experience with specific CRM APIs (HubSpot, Salesforce, etc.) * AI tooling familiarity * Experience with high\-volume data processing * DevOps/cloud deployment experience * Prior startup experience **What You’ll Get** * Real ownership over your work and visibility into how it impacts users * Collaboration with a sharp team across product, design, and leadership * A fast\-moving environment where ideas are welcomed and results matter * Competitive salary: $2,500 – $3,000 USD/month (PJ contract) * Unlimited PTO and true flexibility * Team lunches and regular team\-building activities **Things to Consider** * This is a Contract (PJ) position with potential for growth * Hybrid role: 1–2 days per week in the Curitiba office, remaining days remote * Must have a flexible schedule and be available to work during U.S. hours (MST) * Strong written English required * Comfortable speaking English in meetings and technical discussions We’re not hiring just to fill a seat. We’re hiring someone who wants to make a difference, contribute at a high level, and help us scale with quality and clarity. If that sounds like you, let’s talk!