Select Page

Web API Transition Guide



Web API Transition Guide

Getting Started

Transitioning your customer base from RETS to a certified RESO Web API service requires significant planning and communication. To provide you a path forward, RESO collaborated with MLS organizations that have already converted their customers to Web API to bring you this best practices guide.

Set your team up for success by leveraging this roadmap, developed through the experiences of MLS industry leaders.



Analyze Your Data Customers
How many of your IDX vendors are currently using RETS feeds? How many VOW and back office customers are there? How many data consumers are enterprise vendors (unique agreements like syndication that differ from the traditional broker/vendor/MLS relationship)?

Creating a detailed list of data customers is the first step to guide your organization and your technology vendor to a reasonable timeline for the transition process. Consider updating your contacts in your Customer Relationship Management (CRM) or Association Membership System (AMS): a technology, compliance and billing contact for each customer will allow you to better customize communications down the road.

Choose Your Web API Service(s)
You may have already selected a Web API vendor. Some MLSs use their primary MLS software provider. Others use a Web API service from a different provider. Many MLSs provide multiple Web API services to their customers. (The terms provider and vendor are often used interchangeably in the industry.)

RESO has compiled a list of certified Web API service providers, and information about usage of certified Web API services by MLSs is available on RESO Analytics. RESO makes no claims, warranties or recommendations for these services outside of certification status. Consult with these service providers and select the service that best meets the needs of your customers.

Consult Your Vendor’s Guide for Transition
This guide is a general plan to help your team prepare and organize for the transition. Your vendor will likely have additional steps and documentation which you will need to adapt into your overall plan.

If you provide multiple Web API service options for your customers, you will want to create a guide with separate, customized plans for each vendor system. This includes both the staff plan and a customer plan.

Set a Timeframe for the Transition
How long will it take your organization to transition all of your customers to Web API? Experiences vary, but many organizations complete the bulk of the process in six to nine months. 

After consultation with your vendor and an analysis of your customers, you will be able to decide on your timeframe. This should be a fairly quick process, the goal being a reasonable estimate with the ability to adjust later.

Set a Date for Full Conversion
With your transition timeframe set, your start date will determine your full conversion completion date. Consider the time of year and how the inevitable last-second rush by your customers might affect staff capabilities, especially related to:

  • Holidays
  • Board/budgeting/strategic planning meetings
  • Committee or staff projects
  • Other planned technology changes
  • Conferences and travel

Train Staff to Guide Customer/Vendor Interaction
The MLS will communicate the plan, but your customers will be doing the legwork for converting their data access with the vendor. Staff should understand the forms, steps and people that customers will need to interact with. A point person or team for the technical conversion should be identified.

Walk through the steps a customer would take for this part of the conversion process. Produce a guide for staff that identifies the topics and documents that customers will need to work with the vendor(s).

Not every staff member needs to understand all of the details of these subjects. They do need to know where to direct the customer:

  • Initiation: MLS or vendor leads communications with customers
  • Understanding the rules: Usage and display guidelines
  • License agreements: Authorization for data use (physical or web forms)
  • Billing structure: MLS and/or vendor
  • Getting access: Authentication through API tokens/keys/credentials, data endpoints
  • Vendor technical instructions: How to make requests, unique rules, test vs. live data
  • Mapping documentation: How unique/local fields will be preserved and any changes in naming conventions (it is critical that your staff and vendor are on the same page for your complete data set prior to customer transition)
  • Best practices: Replication, rate limits, etc.

Communications Plan

Communications: Messaging

Start with Focus
Your messaging to data customers must cut through the noise. Assume that recipients have other priorities. Be concise.

Calls to action should be specific and active. One MLS found that this subject line got the attention of distracted customers: 

“We’re not kidding: act now before we shut off your RETS feed.”

As with every step in this process, you may choose to use templates from your vendor or have them manage communications directly with customers.

Explain Why
Your customers will be required to convert, but knowing why lessens the pain. In your initial outreach, express the positives: 

  • The industry is moving past RETS, and Web API is the consensus modernization
  • There are costs to transition, but Web API is more cost effective for everyone long-term
  • To access new, innovative products for brokers and agents, this is a necessary step
  • REALTOR®-operated MLSs have been working with the National Association of REALTORS® for many years to make this technology upgrade available to MLS participants and subscribers

Build Customer Email Templates
Your customers will receive consistent, repeated messaging about the transition for the duration of your campaign. Staff will craft the email content prior to initiating the process.

The initial outreach email to customers begins with the who, what, when, why and how:

  • Who: MLS data customers
  • What: RETS to Web API conversion
  • When: Your timeline
  • Why: Technology modernization as a member benefit
  • How: Your step-by-step guide

The step-by-step guide for customers will explain that they should test the Web API service early in the process while continuing with RETS until they are ready to cut over completely.

Build Staff Email Templates
Your staff must be on the same page during this process. Confident, consistent staff buy-in will convey confidence to customers.

Create staff email templates for responding to individual customer responses, outside of the general customer campaign:

  • Consistent responses to pre-identified Frequently Asked Questions
  • Concise answers to likely objections
  • Include communication dates in your transition schedule
  • Link to MLS web page for customer-facing content that addresses the when and how
  • Identify a staff point person for customer questions

Communications: Schedule

Month 1: Weekly Emails with Only the Most Important Points

  • Create an active subject line (e.g., “IMPORTANT: Changes to Your Data Download from XYZ MLS Are Due Next Month”)
  • Make the what and why clear
  • Have concise bulleted items for the when and how
  • This content should be duplicated on a page of the MLS’s website for easy reference by staff and customers

Month 2: Segmented Audience Emails and Follow-up Phone Calls
Create an active subject line that addresses different audiences to get their attention: “IDX Vendors: Your XYZ MLS RETS Feed Requires Changes.” Repeat for VOW, BBO and enterprise vendors.

  • Have a concise what, why, when and how
  • Call vendors, particularly large/critical MLS vendors to ensure they are receiving emails and understand the timeline.

Months 3–6: Stronger Messaging

  • Increase urgency with your subject line: “Hard Cutoff of Your XYZ MLS RETS Feed: Deadline Imminent”
  • Address when and how

Month 7: Cutoff

  • Apply further emphasis with your subject line: “You Are Not in Compliance: Your XYZ MLS Data Feed Has Been Terminated”
  • Be clear: “Over the past six months, we have sent repeated instructions to transition your data feed to Web API. The deadline has passed, and your RETS feed has been shut off. Please contact us immediately to rectify the situation.”

Communications: Distribution

Consider Non-Email Communication Methods
While email will be your primary method of communication with customers, consider additional options. Are there other areas where your staff can communicate this process to customers?

  • Mailers (dues, events, elections)
  • MLS or association office
  • MLS or association website dashboard/messages
  • MLS or association meetings
  • Designated staffer to make individual calls to late converters

Request Vendor Outreach Support
Web API software vendors will sometimes engage directly in sending emails to your customers. Some have mailed new license agreement letters to be signed by data recipients. 

Vendor platforms for Web API services may have internal messaging capabilities that you can also use with your customers. Consult with your vendor as to their capabilities.



Kick Off with Confidence
You are on your way to modernizing your MLS for the benefit of your customers and the consumer marketplace. Your team is projecting confidence to customers and following a well-documented path in which many organizations have successfully moved their MLSs forward. 

There will be unique challenges for each MLS, but the roadmap is clear.

Stop Creating New RETS Connections Prior to Transition
Your staff can stop issuing new RETS credentials months before starting the transition for current RETS customers. This period will help work out any kinks in the onboarding process and ensure the transition customer base is not growing in the meantime. Starting on RETS and shortly after being required to transition to Web API will create unhappy customers.

Assign an Owner to the Schedule
While your final date for full conversion might shift in the end, a point person on staff should own the schedule and ensure that it is adhered to as much as possible. Consistency will be critical for customers and staff to communicate and execute throughout this process.

If you are a smaller organization, this schedule owner may be the AE/EO/CEO. It could be the MLS Director, a technical staff member or a project manager. Make sure that everyone on the team knows who has ownership of the plan.

Winnow Your Communications Audience Over Time
No one likes to be bombarded with information that is not relevant to them. Maintain a feeling of customized service for your customers by removing them from your transition communications campaign as they convert to Web API.

Schedule regular meetings with your vendor for updates on the number of customers starting the transition and overall completion percentage. Have the staff point person continually update a shared document with the vendor.

Prepare for Outliers
There has not been a Web API conversion yet where there was not at least one customer with a special last-second concern. So plan your responses and personalize your focus on the last customers to make the transition.

  • Provide flexibility with limitations. Have a default extension time period for those whose service gets cut off. Mistakes are made, but guard rails are needed. Give them 7, 14, 30 days – whatever works for your staff – but have a policy and be consistent.
  • Assign a point person for last-second conversions, if necessary. There may be significant hand holding for an aggravated customer at this stage. The lead person for the entire transition plan may not be the best person to handle that volume of interaction.

Publish Progress and Completion
Email to document your progress toward total Web API conversion. Share milestone successes with your team and your customer base. Simply reaching five or ten percent conversion is a significant step toward the success of your initiative.

When you have reached full conversion, you can celebrate with your team and the industry’s leading edge MLSs at the top of the T-RETS Extinction leaderboard. Congratulations!


Certified RESO Web API Service Provider Documentation and Contacts


Thank you to our member organizations and individual contributors who shared their best practices to help guide industry counterparts forward.

  • Shay Lawson, West Alabama Multiple Listing Service
  • Acacia Voynar, IRES MLS
  • Phillip Kent, REsides MLS
  • Marcia Stirling, Cape Cod & Islands Association of REALTORS®
  • Melissa King, OneKey MLS
  • Bill Cole, MIAMI REALTORS®
  • Casey Hickman,
  • Chris Haran, MRED
  • Donna Gould and Matthew Cohen, CoreLogic
  • Joseph Szurgyi, MLS Grid
  • Kristin Youngk, Bridge Interactive
  • Cover Photo by Mathew Schwartz
Subscribe To Our Blog!

Subscribe To Our Blog!

Join our mailing list to receive the latest news and updates from our team.

You have Successfully Subscribed!