I have a lot of space

Import your availabilities

Upload the sheet you already keep, or a CoStar or LoopNet export. We check every row, show you exactly what will post, and match each space against every active requirement. Free, up to 50 spaces at a time.

A CoStar or LoopNet export goes in as it comes, Excel or CSV: Space Use is read as the property type, Space Type (Direct or Sublet) as the deal, and Floor and Suite join the address. A row missing a size, or an asking rent for a lease, is flagged with what to add. Upload only spaces you own or are authorized to market, and check your CoStar or LoopNet agreement before reusing their photos or research data. There is no fee, no commission and no exclusive, so the same spaces can stay on LoopNet and Crexi. One space instead? List it on the form. Want to see who is looking first? Read the tenant requirements.

Broker? See how matching works, what a listing gets and how intros protect your contacts.

Column guide

Header names are flexible: “Size”, “SF” and “RSF” all work, and so do “Rent”, “Asking rent” and “Building” for the address. Columns we do not recognize are ignored. In an Excel file, title rows above the header are skipped, a building name merged down over its floors counts for each floor, and hidden rows and columns are left out.

  • addressRequired

    Street address, e.g. 41 Madison Ave. Put the floor or suite here or in its own floor column. A column named Building or Property works too.

  • neighborhood

    Leave it out for New York City addresses: we look the neighborhood up from the address on city records. Or use one of our names, e.g. Flatiron, SoHo, Long Island City, Dumbo.

  • size_sfRequired

    Rentable square feet, e.g. 4,800.

  • zip or borough

    Helps when an address exists in two boroughs, e.g. 350 Fifth Ave is in Manhattan and in Brooklyn. A ZIP or borough inside the address works too.

  • deal_type

    lease, sublease or sale. Blank rows use the default you pick.

  • property_type

    office, retail, industrial, flex, medical, restaurant or land. Blank rows use your default.

  • rent_psf

    Asking rent in $/SF/yr, e.g. 68. Required for lease and sublease.

  • price

    Asking price for sales, e.g. 4250000 or $4.25M.

  • floor

    Floor or suite, added to the address, e.g. Floor 9.

  • title

    Headline. Blank rows get one like "4,800 SF office for lease in Flatiron".

  • divisible_to

    Smallest divisible size in SF.

  • available

    2026-11-01, 11/1/2026 or "immediately".

  • features

    Separated by semicolons, e.g. Pre-built; Near subway; Freight elevator.

  • description

    Anything else a tenant should know.

  • photos

    Links to photos of the space you may use, separated by spaces or semicolons, up to 12 per space. Direct image links, Dropbox and Google Drive share links work (shared with anyone who has the link). We copy them onto Leasemark when you post.

All 81 neighborhood names we cover

Midtown, Grand Central, Times Square, Hudson Yards, Hell's Kitchen, Garment District, Midtown South, Flatiron, Union Square, Chelsea, Meatpacking, SoHo, NoHo, Tribeca, Hudson Square, Financial District, Murray Hill, Greenwich Village, West Village, East Village, Lower East Side, Chinatown, Harlem, Upper West Side, Upper East Side, Washington Heights, Williamsburg, Greenpoint, Bushwick, Dumbo, Downtown Brooklyn, Sunset Park, Gowanus, Park Slope, Red Hook, Bed-Stuy, Crown Heights, Flatbush, Midwood, Bay Ridge, East New York, Canarsie, Flatlands, Mill Basin, Sheepshead Bay, Borough Park, Coney Island, Fort Greene, Long Island City, Astoria, Flushing, Jamaica, Maspeth, Ridgewood, Jackson Heights, Elmhurst, Sunnyside, Woodside, College Point, Glendale, Forest Hills, Richmond Hill, Springfield Gardens, South Bronx, Hunts Point, Fordham, Concourse, Co-op City, Tremont, Westchester Square, Kingsbridge, West Farms, St. George, Stapleton, Port Richmond, Mariners Harbor, Bloomfield, New Springville, New Dorp, Charleston, Jersey City.

Every imported space gets its own page and joins search right away. Add photos afterwards from your dashboard with Edit.