Market User Interface

Happening Now: MUI 2.0 Parallel Operations

The MISO Market User Interface (MUI) allows Market Participants to transact with the MISO Energy & Ancillary Services Market. Designed over 15 years ago, the MUI required modernization to meet future performance, usability, reliability and security needs. 

MISO partnered with members to engage in a two-year planning, testing and verification process to replace the MUI by November 2021. This work led to a major milestone on September 8, 2021 when MISO launched MUI 2.0 in parallel operations. 

This change is part of the larger Market System Enhancement (MSE) program to modernize the MISO Energy & Ancillary Services Market system. 

Frequently Asked Questions


  • Other Market Portal navigation tiles
    • Asset Registration Tool
    • Settlements
    • Financial Transmission Rights
    • OATI OASIS and webTrans
  • Other APIs such as
    • Outage Scheduling

Module-E Capacity Tracking (MECT)

Phase 1 – Customer Engagement (Jan 2019 – Mar 2020) – MISO host a series of workshops and roll out specifications. This is when you can provide feedback on design, begin your planning and prepare for development and testing.

Phase 2 – Member Development and Testing (Apr 2020 – Aug 2021) – Focus will shift to completing development and testing.

Phase 3 – Parallel Operations (Sep – Dec 2021) – MISO will have both the legacy and MUI 2.0 available in production. Market Participants can use either system and choose the best window to migrate over. Goal is to have 100% of Market Participants migrated to MUI 2.0 by end of Parallel Operations.

Phase 4 – Legacy Retirement (Jan 2021) – MISO will shut down the legacy MUI and only the new MUI 2.0 will be available.

Designed over 15 years ago, the MUI requires modernization to meet future performance, usability, reliability, and security needs. 

The MUI allows Market Participants to submit market transactions and query market results. The current MUI is a Web Services/XML based design with a XSD scheme defining the transaction. The new MUI is a RESTful API/JSON design with an OpenAPI Specification (Swagger) schema

In addition to the technical changes, a few usage patterns will change. For example, the new MUI allows for one submittal per transaction instead of multiple submittals in a single transaction. 

Both the API and the user interface is changing. 

MISO will release preliminary and final technical specification as they become available. 

The transaction types, transaction content requirements and market rules will remain the same.