API Technical Specifications for Dispatch Services and MIM

As part of the Market Renewal Program, changes are being made to the way Market Participants will interact with the Market Information Management (MIM) and the Dispatch Services systems. These applications are currently used by dispatchable Market Participants to submit bids and offers for the physical market and to receive dispatch instructions from the IESO. To prepare Market Participants, the IESO will post an updated set of API technical specifications, schema and sample files in the section below. Further details on the release of the updated materials are noted in the Participant Readiness Memo.

Market Information Management System

Dispatch Service System (to be published on or before March 30, 2023)

  • Dispatch Service Web Service Design Specifications (SPEC-154)
  • Dispatch Notification Service Web Service Design Specifications (SPEC-155)


The Market Renewal Program (MRP) is bringing necessary and fundamental changes to the electricity market in Ontario. These changes will bring greater financial and operational certainty to participants, provide benefits to Ontario ratepayers, and build the foundation of Ontario’s electricity market to prepare for continued change in the sector. MRP builds from the existing electricity market that has been meeting Ontario’s reliability needs cost-effectively for the past two decades, by improving efficiency, removing out-of-market programs and levelling the playing field to bring greater competition between resources.

As the IESO continues to work closely with stakeholders to answer questions, and finalize the Market Rules and Market Manuals that will govern the future market, it is time to begin to scope the changes that are coming for market participants.

The links below are the ‘Day-In-The-Life’ documents for each of the 13 participant types. Participants who have more than one role in the Market will want to review the documents specific to each one of those roles.

Work on a full suite of training plans and materials is underway and the IESO will share more information when available.

This Day-In-The-Life summary begins to solidify how participants can embrace and prepare for Market Renewal, so that all participant readiness activities can be completed prior to in-service and the sector can move confidently into the advent of the renewed market.