SimplyRETS vs Spark API: a REST layer on your own MLS feed or MLS data for Flexmls apps
SimplyRETS is a developer API and WordPress plugin that turns your own MLS's RETS or RESO Web API feed into a simple REST listings API. FBS's Spark API and RESO Web API give authorized applications access to MLS data on the Flexmls/Spark platform.
The short answer
- SimplyRETS: An affordable, simple REST layer for an agent or brokerage that already has its own MLS data feed.
- Spark API: Apps built for agents, brokers or MLSs that use Flexmls, where the MLS member authorizes access.
Side by side
| SimplyRETS | Spark API | |
|---|---|---|
| Searches | Listings from the MLS feeds you connect: active, under contract, pending and closed; residential, condo, rental, multifamily, commercial and land, plus open houses. | MLS listings (and, for VOW apps, sold data) from participating MLSs, within the roles each MLS grants. |
| Returns | Listing records with property details, photos, and listing agent and office information when the MLS feed supplies it. | MLS listing records in Spark or RESO Web API format. |
| Before the first call | RETS or RESO Web API credentials from your MLS; whether you must be an agent or broker depends on the MLS. | A free developer account, then an MLS data plan or an MLS member who authorizes your app. |
| Free | Free demo API keys with sample data; no free trial with live data. | Developer account sign-up is free. |
| Paid | Basic plan $49 a month, plus a one-time $99 fee per MLS connection. | $50 a month for each MLS you access, once you have data from your first MLS (MLS data plans may set their own terms). |
| Acting on a result | Listing agent and office contact details come with each listing when the MLS feed has them, and some MLSs require showing them. | Not stated on its pages |
| Limits on keeping or showing results | Only listings flagged for IDX display are served, and you must follow the display rules (e.g. last-updated disclaimers) set by your MLS. | No storing MLS content except temporary caching for performance, unless your key permits replication; MLS display rules and license terms apply. |
| Coverage | Whatever MLS you connect (US); no fixed national coverage. | Participating MLSs on the FBS platform; no list or count on its pages. |
| MCP server | No official server listed | No official server listed |
Where AgentBeacon fits
AgentBeacon has no home beacons yet. Anyone can create one, and agents will find them through the same search as jobs and businesses.
Questions people ask
What do I need before I can use SimplyRETS?
RETS or RESO Web API credentials from your MLS; whether you must be an agent or broker depends on the MLS.
Is SimplyRETS free?
Free demo API keys with sample data; no free trial with live data.
What do I need before I can use Spark API?
A free developer account, then an MLS data plan or an MLS member who authorizes your app.
Is Spark API free?
Developer account sign-up is free.
Sources
Every line about another company comes from its own pages. Prices and terms change, so check the source before you rely on one.
SimplyRETS, read on October 15, 2026:
- simplyrets.com: “These are our demo API keys, you can use them!”
- simplyrets.com: “Each RETS or RESO Web API connection requires one time $99 connection fee.”
- simplyrets.com: “Get RETS or RESO Web API credentials from your MLS”
- simplyrets.com/faq: “This is dependent on the MLS area you want to connect to.”
- docs.simplyrets.com/topics/fields-and-features-for-idx-compliance: “In some cases it may be required that you show the contact information for the listing agent and/or listing office.”
- docs.simplyrets.com/topics/fields-and-features-for-idx-compliance: “in many areas it’s required to show the timestamp of when the data was last updated in a disclaimer.”
- simplyrets.com: “Basic $ 49 /mo”
- simplyrets.com/faq: “We don't currently offer a free trial period with live data”
Spark API, read on October 15, 2026:
- sparkplatform.com/docs/overview/api: “The Spark API allows authorized MLS members to request data through developer applications”
- sparkplatform.com/docs/overview/api: “When IDX applications are purchased, the MLS member must authorize that application to access their data.”
- sparkplatform.com/docs/overview/faq: “It’s free to sign up for a Spark API developer account.”
- sparkplatform.com/docs/overview/faq: “Once you have access to data from your first MLS, API access costs $50/mo for each MLS you can access.”
- sparkplatform.com/docs/terms_of_use/developer_agreement_and_terms_of_use: “except for temporary caching purposes necessary for performance enhancement”
- sparkplatform.com/docs/terms_of_use/developer_agreement_and_terms_of_use: “Compliance with MLS Rules and License Terms regarding MLS Content”