NOTICE DATE: November 21, 2025

NOTICE TYPE: M-C110625-02 System Changes

SHORT DESCRIPTION: ERCOT Change to End-Point URL Address for External Web Services API in Production Environment

INTENDED AUDIENCE: All Market Participants

DAYS AFFECTED: December 4, 2025

LONG DESCRIPTION:  This is a follow-up to the November 6, 2025 Market Notice, as a reminder that ERCOT will be changing the External Web Services Application Programming Interface (API) end-point URL address that many Market Participants use to access ERCOT systems with XML interface.  This reconfiguration will occur at approximately midnight between December 4-5, 2025.

ERCOT will be transitioning from these External Web Services API end-point URLs:

        Current Internet API URL: https://misapi.ercot.com/2007-08/Nodal/eEDS/EWS/

        Current WAN API URL: https://api.wan.ercot.com:8443/2007-08/Nodal/eEDS/EWS/

To the new External Web Services API end-point URLs:

        New Internet API URL : https://misapi.ercot.com/NodalAPI/EWS/

        New WAN API URL: https://api.wan.ercot.com/NodalAPI/EWS/

This change will affect all Market Participants that use machine-to-machine External Web Services API interfaces.  This will not impact Market Participants that access the Market Information System (MIS) or other ERCOT websites through a web browser such as Market Manager User Interface (UI), Outage Scheduler UI, or Network Model Management System.

ACTION REQUIRED: Market Participants that use External Web Services API end-point URLs connectivity to ERCOT need to be prepared to reconfigure their system connections on or after midnight December 5, 2025.  Market Participants should also be aware of the related Market Notice, M-B111325-01 RTC+B: ERCOT API/XML Interface Listener Setup for QSEs without Resources.

ADDITIONAL INFORMATION: ERCOT is not making changes to the following security items: 1) SSL certificates used to secure the API websites, or 2) Client API certificates used for authentication to the API websites.

CONTACT: If you have any questions, please contact your ERCOT Account Manager. You may also call the general ERCOT Client Services phone number at (512) 248-3900 or contact ERCOT Client Services via email at ClientServices@ercot.com.

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dg