Zoho CRM to Companies House — XML Gateway Middleware Build

We are an accountancy practice (Optimise Accountants Ltd) that has already built a fully automated client confirmation workflow in Zoho CRM. When a client confirms their company details are correct, we need the CS01 Confirmation Statement to be filed automatically with Companies House via the XML Gateway eFiling service — with zero staff intervention.

Phase 1 (client confirmation flow) is complete and live. We need Phase 2 only: a middleware layer that receives company data from Zoho CRM, constructs the CS01 XML payload, authenticates with Companies House XML Gateway, submits the filing, and writes the result (reference number, filed date, or error) back to the Zoho CRM record automatically.

Full technical brief attached. Please read it before bidding.

IMPORTANT: We will only consider bids from developers who have previously worked with the Companies House XML Gateway eFiling service specifically — not the Companies House REST API, and not general API developers. Please confirm this experience explicitly in your bid.