I need a production-ready API layer that lets our existing Microsoft Dynamics ERP push sales invoices to ZATCA in Saudi Arabia, retrieve the clearance response, and then write the approved XML and embedded QR code back to Dynamics for printing and archiving. The job covers: • A secure REST or SOAP service (your call) that receives data from Dynamics, converts it to ZATCA-compliant XML (UBL 2.1), signs it, and sends it to the authority’s portal. • Handling of cryptographic certificates, timestamps, UUID generation, and any hash/CSID requirements so the submission passes Phase 2 validation. • Parsing the authority’s response, extracting the cleared XML and QR, and exposing them to Dynamics via lightweight endpoints or a stored procedure wrapper. • A small test harness that can fire sample documents against ZATCA’s sandbox so we can demonstrate the full round-trip before moving to production. • Clean installation guide and commented source so our internal team can maintain it. Acceptance criteria 1. An invoice created in Dynamics is cleared by ZATCA in the sandbox with no errors. 2. The returned XML and QR render correctly on the printed invoice. 3. All calls are logged with request/response IDs and timestamps for auditing. 4. Solution installs on a fresh Windows Server in under 30 minutes using the guide provided. I will give you access to our Dynamics database schema, a test company, and the required ZATCA keys once we agree on the tech stack.