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Interface Design Document (IDD) Template

Complete Word template for designing one system interface: scope, pattern choice, message specification, error handling, security, NFRs, testing, cutover and sign-off.

Free

Free Word template. Complete Word template for designing one system interface: scope, pattern choice, message specification, error handling, security, NFRs, testing, cutover and sign-off. Download it, add your project details and use it today: no sign-up for software, no paywall.

An interface that is not designed on paper gets designed during system integration testing, which is the most expensive place to do it. This IDD template walks integration architects and functional consultants through every decision a reviewer will ask about: business context and rules, pattern selection with rejected alternatives, endpoints and keys, transformations, error categories, retries and idempotency, reconciliation, security, non-functional targets, environments, testing, cutover and support. Guidance notes explain what good looks like, and a review checklist and sign-off table close the document. Works for Dynamics 365 finance and operations, Dataverse, and any API, message, or file-based integration.

What's inside

  • Interface Design Document (IDD)
  • Document control
  • 1. Purpose and scope
  • 1.1 Purpose
  • 1.2 In scope
  • 1.3 Out of scope
  • 2. Interface summary
  • 3. Business context
  • 3.1 Business process
  • 3.2 Business rules
  • 3.3 Assumptions and dependencies
  • 4. Solution design
  • Guidance notes and placeholders so you can fill it in quickly

How to use it

  1. Create one IDD per interface (or per tightly coupled set of flows) and give it the same ID used in your interface register and field mapping sheet.
  2. Complete sections 1 to 3 with the business owner first. Agree scope, out-of-scope items and business rules before discussing technology.
  3. Fill in section 4 with the integration architect. Record the alternatives you rejected and why; reviewers and future support teams will need this.
  4. Keep field-level mapping in the separate mapping sheet and reference its version in section 4.4, rather than copying tables into the document.
  5. Do not skip sections 5 to 7. Error handling, security and volumes are where most integration defects and audit findings come from.
  6. Run the Appendix B checklist in a design review, log open points in section 12, and collect sign-off in Appendix C before build starts.
  7. Update the version table whenever the design changes after sign-off, and re-approve material changes.

Who it's for

Solution architects, integration leads and consultants connecting Dynamics 365 with POS, EDI, WMS, CRM and the Power Platform.

Let's connect

I'm Pranshu Shubham, a Microsoft Dynamics 365 F&O Solution Architect and PMP-certified program lead with 8+ years of ERP and AI transformation across the USA, Europe and APAC. I created this resource from real project experience, and I'd love to hear how you use it.