The short answer
You get MLS data by licensing it from each MLS you need, not from a standards body or a single national source. RESO, which publishes the data standards, does not provide MLS data and directs data requests to MLSs. In practice you choose the license type that matches your use, usually find a broker who is an MLS member to sponsor or ratify the agreement, apply and pass the MLS's review, and then receive credentials, either directly from the MLS or through a delivery platform such as MLS Grid, Trestle or Bridge.
Decide which license you need
MLSs license the same listings under different terms depending on how you will use them. The common categories:
- IDX (Internet Data Exchange) for public listing display on a broker's website. Under NAR policy, participants may not use IDX-provided listings for any purpose other than IDX display.
- VOW (virtual office website) for registered consumers who have first established a lawful consumer-broker relationship with the broker; a broker may designate an “Affiliated VOW Partner” to operate a VOW.
- Broker back-office or internal use, for CRMs, reporting and analytics. Stellar MLS requires that firm-internal and VOW applications reside behind a login and be non-accessible to the public.
- Vendor or technology-provider licenses for companies whose product, used by MLS members, is built on the data. ARMLS describes vendors as companies that create products used by ARMLS subscribers that incorporate ARMLS data.
The names vary by MLS. Stellar MLS lists Firm Internal Use, Broker Data Release, VOW, Vendor Product and IDX; MLS PIN offers broker, vendor/third-party and syndicator access, plus two free IDX options. Read each MLS's own data page before you design, because the category decides what you may show, to whom, and what it costs.
Find a sponsoring broker
Most MLSs license data to companies that serve their members, so a member broker is usually part of the agreement:
- Stellar MLS requires a three-party agreement between the Broker, Vendor, and Stellar MLS for custom feeds, with an individual agreement for each broker you work with. A vendor product must be actively working with at least one Broker that belongs to Stellar MLS.
- At ARMLS, broker data feed requests must be associated with an active ARMLS subscriber, and all feeds must be used under broker control.
- Trestle notes that MLOs typically require a real estate broker or agent to ratify the contract, or a periodic report of which members use your service.
- If you are a brokerage building your own technology, MLS Grid's access guide says your brokerage will function as your own “Vendor”.
Find out how each MLS delivers data
Some MLSs deliver feeds themselves; many use a platform. The platform changes the paperwork, not the need for MLS approval.
- MLS Grid has one standard license agreement across its feed types. It says you will only pay the license fee required by your MLS, which MLS Grid collects on the MLS's behalf, and that participation is at your MLS's discretion. NorthstarMLS, for example, requires that VOW or back-office agreements be completed through the MLS Grid.
- Trestle (Cotality): you register and click “ADD MLO CONNECTION” to begin the data request workflow. Trestle only facilitates the license agreement; Cotality is not a party to it.
- Bridge Interactive (Zillow): all datasets require approval from the data provider, which may require license agreements, fees or compliance testing; every application gets automatic access to a test dataset. Zillow's developer page says the platform is currently invite only.
Apply and pass the review
The steps are similar everywhere: apply, sign, show your product, get approved, receive credentials.
- Stellar MLS asks you to fill out an online questionnaire, then its Data Delivery team contacts you. You need the ability to demonstrate a fully working application; sample or demo data is only available in MLS Grid without prior approval.
- ARMLS runs broker and vendor requests through intake forms that you submit for ARMLS review.
- MLS Grid's guide lays out the order: register, choose the MLS, sign the Data License Agreement, add your broker or agent customers with a site or staging URL for MLS review during the approval process, then pay upon approval by the MLS and receive an access token.
- NorthstarMLS reviews the request and, if approved, provides a license.
None of the MLS or platform pages cited here publish an approval timeline, so ask each MLS how long its review usually takes before you commit to a launch date.
Budget for the fees
Fees are set by each MLS, and platforms may add their own. Published examples:
Our MLS and IDX integration cost guide compares these fees with IDX vendor subscriptions and development costs.
Build on the RESO standards
RESO describes the Web API as the modern way to transport data in the real estate industry, and says RETS has been deprecated and is no longer supported. The RESO Data Dictionary standardizes field names, with more than 1,700 fields and 3,100 lookups. RESO also tests technology systems to confirm compliance with ratified standards, so an MLS's certification status tells you how closely its feed follows the standard. Building against the Data Dictionary makes adding a second or third MLS a mapping exercise rather than a rewrite.
Stay compliant after launch
- Refresh: IDX displays must refresh not less frequently than every 12 hours; VOWs not less frequently than every three (3) days. In Canada, CREA DDF® websites must refresh at least once every twenty-four (24) hours.
- Attribution: an IDX display must identify the listing firm, and the email or phone number provided by the listing participant.
- Monitoring and audits: participants must give the MLS direct access for purposes of monitoring/ensuring compliance; an MLS may require an audit trail of registrants' activity on the VOW; and Stellar vendor products are subject to routine data audit checks for compliance.
These rules shape the architecture: sync frequency, where attribution appears, and what you log. Our W3|re case study shows a pipeline built across four MLS systems.
Frequently Asked Questions
Can we get MLS data without a broker?
Usually not directly. MLSs license data to companies that serve their members, and many require a member broker to sign or ratify the agreement. Stellar MLS, for example, requires a three-party agreement between the Broker, Vendor, and Stellar MLS, and Trestle notes that MLOs typically require a real estate broker or agent to ratify the contract.
Does RESO provide MLS data?
No. RESO publishes the data standards, but does not provide MLS data and directs data requests to MLSs.
Do MLS Grid, Trestle or Bridge charge their own fees?
It varies. MLS Grid says you will only pay the license fee required by your MLS, Bridge says it charges no additional service fees, and Trestle charges $30 to $175 per connection per month depending on the feed and customer on top of MLS fees.
How often must listing data be refreshed?
Under NAR policy, IDX displays must refresh not less frequently than every 12 hours and VOWs not less frequently than every three (3) days. Individual MLSs can set their own rules, so check each license.
How long does MLS approval take?
None of the MLS or platform pages cited in this guide publish an approval timeline. Approval usually involves a review of your application and a working product, for example Stellar MLS asks for the ability to demonstrate a fully working application, so ask each MLS how long its review takes.
Requirements and fees were taken from the linked MLS, NAR, RESO, MLS Grid, Trestle and Bridge pages on September 30, 2026. On October 9, 2026 the CREA citation was updated to CREA's June 2026 rules. On that date NAR's policy handbook required a member login and NorthstarMLS's page could not be reached, so the NAR and NorthstarMLS statements are as read on September 30. Policies and fees change and differ by MLS; confirm them with each MLS before you apply.
Planning an MLS integration? See our RESO Web API and MLS data feed development service or talk to an engineer.
