Integration Developer - HubSpot × Unleashed ERP Integration

Overview We're a RevOps agency looking for an experienced integration developer to build a bi-directional integration between HubSpot CRM and Unleashed inventory management for one of our clients (a B2B manufacturer). The integration covers several data flows including a product and pricing sync, customer sync, quote-to-order automation, order and fulfilment tracking, asset registration, warranty validation, and RMA processing. Full architecture documentation and data flow diagrams will be provided at engagement. You'll be working under our project lead so there will be no direct client contact. You will be expected to deliver working flows, provide full documentation, and walk our team through the build before sign-off. Platform n8n (preferred): The client already has an n8n cloud subscription. Visual workflow interface makes ongoing monitoring and minor adjustments feasible for a non-technical team. This is our default expectation for most flows. Where alternatives may be appropriate: If you believe a specific flow would be better served by a different approach (e.g. Make), flag it in your proposal with your reasoning. At least one flow requires a real-time server-side lookup that may suit an endpoint better than a standard workflow tool. Whatever is built needs to be understandable, monitorable, and modifiable by a non-technical team without a developer on retainer. This is a hard requirement. We are not looking for managed middleware platforms with significant ongoing subscription costs, or fully custom codebases that require a developer to maintain. What We Provide • Detailed architecture documentation including data flow diagrams for each of the 7 flows • HubSpot and Unleashed API credentials • Access to the client's n8n instance (cloud) • A HubSpot sandbox environment for development and testing • Clear acceptance criteria per flow • A single point of contact for all questions and approvals Requirements • Proven experience integrating HubSpot with inventory/ERP systems is essential. This includes platforms such as Unleashed, DEAR, Cin7, TradeGecko, or similar. Please provide specific project examples (proposals without evidence of HubSpot-to-ERP integration work will not be considered). • Experience with the HubSpot API, including custom objects, associations, and CRM Search • Experience with REST API integrations involving inventory/ERP platforms (Unleashed uses HMAC-SHA256 authentication) • Comfortable building webhook endpoints that return real-time responses • Strong documentation habits (we need to maintain this after handover) Nice to Have • Prior experience with Unleashed • Experience with HubSpot custom objects and association APIs • Experience building server-side form validation endpoints Deliverables 1. Working integration: all flows plus shared infrastructure (auth, error handling, monitoring), deployed and tested 2. Documentation: for each flow: trigger, source/destination mapping, matching logic, error handling, and assumptions 3. Walkthrough: a recorded or live session walking our team through the build and how to monitor/troubleshoot 4. Handover pack: everything needed to maintain the integration independently, including how to identify and resolve common error states How We Work • Task management: All tasks, requirements, and progress tracking will be managed in ClickUp. We expect all task-related communication to go through ClickUp (not email or Upwork messaging). You'll be given access to the relevant project board. • Video calls: We expect regular video check-ins (daily or every second day depending on the phase). These are short, focused calls to review progress, unblock issues, and walk through work in progress. Camera on. • English: Strong spoken and written English is required. You'll need to explain technical decisions clearly on video calls and produce documentation that a non-technical team can follow. • Availability: We're based in AEST (UTC+10). You don't need to be in the same timezone, but you do need to have overlap for the regular check-in calls. Engagement Structure • Fixed price: please quote per flow and as a total • Contingency: we're open to a small contingency allocation for edge cases, but the flows are well-documented • Timeline: please indicate your availability and estimated delivery timeline How to Apply 1. Evidence of integration work between HubSpot and an inventory/ERP system such as Unleashed, DEAR, Cin7, TradeGecko, or similar (mandatory) 2. Your recommended platform/approach with reasoning 3. Per-flow and total fixed-price quote 4. Estimated timeline from kickoff to delivery 5. Any questions about the scope Generic proposals will not be considered.