RESO fields

The feed speaks the RESO Data Dictionary, so a site that reads one MLS feed can read this one. Fields we add start with LO_.

Property

RESO field	Type	From	About
`ListingKey`	string	`id`	Listing key.
`OriginatingSystemName`	string	fixed	Always this platform.
`StandardStatus`	string	`status`	RESO StandardStatus.
`ListPrice`	integer	`price`	List price.
`ClosePrice`	integer or null	`soldPrice`	Sold price, when Closed.
`UnparsedAddress`	string	`street, city, state, zip`	Street, city, state ZIP.
`City`	string	`city`	City.
`StateOrProvince`	string	`state`	State.
`PostalCode`	string	`zip`	ZIP.
`PropertyType`	string	fixed	Always Residential.
`PropertySubType`	string	`propertyType`	RESO PropertySubType.
`BedroomsTotal`	integer	`beds`	Bedrooms.
`BathroomsTotalInteger`	integer	`baths`	Bathrooms counted whole: 2 full and 1 half is 3.
`BathroomsFull`	integer	`baths`	Full bathrooms.
`BathroomsHalf`	integer	`baths`	Half bathrooms.
`LivingArea`	integer	`sqft`	Living area.
`LivingAreaUnits`	string	fixed	Always Square Feet.
`LotSizeAcres`	number or null	`lotAcres`	Lot size in acres.
`YearBuilt`	integer or null	`yearBuilt`	Year built.
`PublicRemarks`	string	`remarks`	Public remarks.
`ListAgentFullName`	string	`agent`	Listing agent.
`ListOfficeName`	string	`brokerage`	Listing brokerage.
`ListingContractDate`	string	`listingAgreementAt`	Agreement date.
`OnMarketDate`	string	`createdAt`	Day it went on the market.
`ModificationTimestamp`	string	`updatedAt`	Last change.
`LO_SellerVisibilityChoice`	string	`visibility`	Extension: the seller's choice. Members only never appears here.
`LO_SellerChoiceRecordedAt`	string	`sellerConsentAt`	Extension: when the seller's choice was recorded.
`Media`	array	`photos`	With $expand=Media: the photos, in order.

RESO field: ListingKey
Type: string
From: id
About: Listing key.

RESO field: OriginatingSystemName
Type: string
From: fixed
About: Always this platform.

RESO field: StandardStatus
Type: string
From: status
About: RESO StandardStatus.

RESO field: ListPrice
Type: integer
From: price
About: List price.

RESO field: ClosePrice
Type: integer or null
From: soldPrice
About: Sold price, when Closed.

RESO field: UnparsedAddress
Type: string
From: street, city, state, zip
About: Street, city, state ZIP.

RESO field: City
Type: string
From: city
About: City.

RESO field: StateOrProvince
Type: string
From: state
About: State.

RESO field: PostalCode
Type: string
From: zip
About: ZIP.

RESO field: PropertyType
Type: string
From: fixed
About: Always Residential.

RESO field: PropertySubType
Type: string
From: propertyType
About: RESO PropertySubType.

RESO field: BedroomsTotal
Type: integer
From: beds
About: Bedrooms.

RESO field: BathroomsTotalInteger
Type: integer
From: baths
About: Bathrooms counted whole: 2 full and 1 half is 3.

RESO field: BathroomsFull
Type: integer
From: baths
About: Full bathrooms.

RESO field: BathroomsHalf
Type: integer
From: baths
About: Half bathrooms.

RESO field: LivingArea
Type: integer
From: sqft
About: Living area.

RESO field: LivingAreaUnits
Type: string
From: fixed
About: Always Square Feet.

RESO field: LotSizeAcres
Type: number or null
From: lotAcres
About: Lot size in acres.

RESO field: YearBuilt
Type: integer or null
From: yearBuilt
About: Year built.

RESO field: PublicRemarks
Type: string
From: remarks
About: Public remarks.

RESO field: ListAgentFullName
Type: string
From: agent
About: Listing agent.

RESO field: ListOfficeName
Type: string
From: brokerage
About: Listing brokerage.

RESO field: ListingContractDate
Type: string
From: listingAgreementAt
About: Agreement date.

RESO field: OnMarketDate
Type: string
From: createdAt
About: Day it went on the market.

RESO field: ModificationTimestamp
Type: string
From: updatedAt
About: Last change.

RESO field: LO_SellerVisibilityChoice
Type: string
From: visibility
About: Extension: the seller's choice. Members only never appears here.

RESO field: LO_SellerChoiceRecordedAt
Type: string
From: sellerConsentAt
About: Extension: when the seller's choice was recorded.

RESO field: Media
Type: array
From: photos
About: With $expand=Media: the photos, in order.

Media

Photos come from /api/reso/Media, or with each record through $expand=Media. MediaURL is a signed link on this host that lasts about 12 hours and stops as soon as the listing leaves the feed: copy the photo, not the link. Every photo is a JPEG of at most 2560 pixels on the long side with its location data removed.

RESO field	Type	About
`MediaKey`	string	Photo key.
`ResourceRecordKey`	string	The listing's key (an alias in a members only copy).
`ResourceName`	string	Always Property.
`MediaCategory`	string	Always Photo.
`MediaURL`	string	A signed link to the JPEG on this host.
`Order`	integer	Position from 0.
`ImageWidth`	integer	Pixels; at most 2560 on the long side.
`ImageHeight`	integer	Pixels.
`PreferredPhotoYN`	boolean	True for the first photo.
`ModificationTimestamp`	string	When it was added or last moved.

RESO field: MediaKey
Type: string
About: Photo key.

RESO field: ResourceRecordKey
Type: string
About: The listing's key (an alias in a members only copy).

RESO field: ResourceName
Type: string
About: Always Property.

RESO field: MediaCategory
Type: string
About: Always Photo.

RESO field: MediaURL
Type: string
About: A signed link to the JPEG on this host.

RESO field: Order
Type: integer
About: Position from 0.

RESO field: ImageWidth
Type: integer
About: Pixels; at most 2560 on the long side.

RESO field: ImageHeight
Type: integer
About: Pixels.

RESO field: PreferredPhotoYN
Type: boolean
About: True for the first photo.

RESO field: ModificationTimestamp
Type: string
About: When it was added or last moved.

Our extensions

LO_SellerVisibilityChoice is the seller's recorded choice and LO_SellerChoiceRecordedAt when it was made, so every site can show it honored the seller. Members only never appears: those listings are not in the feed.

Query

Option	Does
`$top`	How many records you want. The server sends at most 50 per page.
`$skip`	Records to skip, up to 100,000.
`$filter`	OData: `eq ne gt ge lt le`, `and or not`, parentheses, `null` with eq and ne. Strings in single quotes, dates as YYYY-MM-DD, timestamps in ISO 8601. Fields: ListingKey, StandardStatus, ListPrice, ClosePrice, City, StateOrProvince, PostalCode, PropertySubType, BedroomsTotal, LivingArea, LotSizeAcres, YearBuilt, ListAgentFullName, ListOfficeName, ListingContractDate, ModificationTimestamp.
`$select`	Comma separated fields to return.
`$orderby`	Up to 5 filterable fields, each optionally `asc` or `desc`.
`$count`	`true` adds @odata.count.
`$expand`	`Media` adds each record's photos, in order, as a Media array. Nothing else expands.
`key`	The API key, for a browser link. Prefer the Authorization header: query strings end up in logs.

Option: $top
Does: How many records you want. The server sends at most 50 per page.

Option: $skip
Does: Records to skip, up to 100,000.

Option: $filter
Does: OData: eq ne gt ge lt le, and or not, parentheses, null with eq and ne. Strings in single quotes, dates as YYYY-MM-DD, timestamps in ISO 8601. Fields: ListingKey, StandardStatus, ListPrice, ClosePrice, City, StateOrProvince, PostalCode, PropertySubType, BedroomsTotal, LivingArea, LotSizeAcres, YearBuilt, ListAgentFullName, ListOfficeName, ListingContractDate, ModificationTimestamp.

Option: $select
Does: Comma separated fields to return.

Option: $orderby
Does: Up to 5 filterable fields, each optionally asc or desc.

Option: $count
Does: true adds @odata.count.

Option: $expand
Does: Media adds each record's photos, in order, as a Media array. Nothing else expands.

Option: key
Does: The API key, for a browser link. Prefer the Authorization header: query strings end up in logs.

curl

curl -G "https://listonce.io/api/reso/Property" \
  --data-urlencode "\$filter=City eq 'Austin' and StandardStatus eq 'Active'" \
  --data-urlencode "\$top=10" \
  -H "Authorization: Bearer ol_demo_7f3a9c2e5b1d4086"

Also served: the service document at /api/reso, the data model at /api/reso/$metadata, every lookup value at /api/reso/Lookup, and one record as Property('OL-4K7Q2M'). $expand takes Media on Property only. Not supported: $search and $apply (501). Order is newest change first unless $orderby says otherwise; follow @odata.nextLink for the next page. The feed follows the RESO Web API Core and Data Dictionary but is not yet RESO certified.

Add and edit

A member brokerage whose system already speaks RESO can enter and change listings in the same field names, as RESO Web API Add/Edit: POST /api/reso/Property and PATCH /api/reso/Property('OL-4K7Q2M') with a listings:write key. It is the same listing, owner and rules as /api/v1/listings. Send two extensions with a new listing: LO_SellerVisibilityChoice and LO_SellerName (seen only by the owner, never in the feed).

Behavior	How
Answer	POST answers 201 with the record, PATCH 204. `Prefer: return=representation` or `return=minimal` picks; Location and EntityId name the record either way.
Retries	Send an `Idempotency-Key` on POST or PATCH; a repeat replays the first answer.
Read only	ListingKey, OriginatingSystemName, ListOfficeName, ModificationTimestamp and LO_SellerChoiceRecordedAt are ignored, so a record you read can be sent back. Any other unknown name is refused.
Errors	OData errors with `target` (Create or Update) and `details` naming each RESO field at fault.

Behavior: Answer
How: POST answers 201 with the record, PATCH 204. Prefer: return=representation or return=minimal picks; Location and EntityId name the record either way.

Behavior: Retries
How: Send an Idempotency-Key on POST or PATCH; a repeat replays the first answer.

Behavior: Read only
How: ListingKey, OriginatingSystemName, ListOfficeName, ModificationTimestamp and LO_SellerChoiceRecordedAt are ignored, so a record you read can be sent back. Any other unknown name is refused.

Behavior: Errors
How: OData errors with target (Create or Update) and details naming each RESO field at fault.

curl

curl -X POST "https://listonce.io/api/reso/Property" \
  -H "Authorization: Bearer $LISTONCE_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
    "UnparsedAddress": "88 Cedar Bluff Dr, Austin, TX 78704",
    "City": "Austin",
    "StateOrProvince": "TX",
    "PostalCode": "78704",
    "ListPrice": 625000,
    "BedroomsTotal": 3,
    "BathroomsFull": 2,
    "BathroomsHalf": 1,
    "LivingArea": 1960,
    "LotSizeAcres": 0.18,
    "YearBuilt": 2004,
    "PropertyType": "Residential",
    "PropertySubType": "Single Family Residence",
    "PublicRemarks": "Quiet street, open kitchen and a covered patio facing the greenbelt.",
    "ListAgentFullName": "Rowan Ellis",
    "ListingContractDate": "2026-10-26",
    "LO_SellerVisibilityChoice": "members_only",
    "LO_SellerName": "A. and T. Monroe"
  }'

Every field and limit is on the Endpoints page. Add/Edit is not RESO certified either.