diff --git a/inc/filetools.ps1 b/inc/filetools.ps1
index ae21ec0..9ce5d06 100644
--- a/inc/filetools.ps1
+++ b/inc/filetools.ps1
@@ -67,3 +67,33 @@ function Get-Package-Client-Dir {
 
     return Join-Path $root $subfolder
 }
+
+# Return whether 2 files seem to be the same based on their size and date/time
+# Does not compare their contents!
+function Compare-Files-Quick {
+    param (
+        [string]$filePathA,
+        [string]$filePathB
+    )
+
+    if (-not (Test-Path $filePathA -PathType Leaf)) {
+        return $false
+    }
+    if (-not (Test-Path $filePathB -PathType Leaf)) {
+        return $false
+    }
+    $propsA = Get-ItemProperty -Path $filePathA
+    $propsB = Get-ItemProperty -Path $filePathB
+
+    if ($propsA.Length -ne $propsB.Length) {
+        return $false
+    }
+
+    $timediff = New-TimeSpan $propsA.LastWriteTime $propsB.LastWriteTime
+    # Allow a 2s difference
+    if ($timediff.Seconds -gt 2) {
+        return $false
+    }
+
+    return $true
+}
\ No newline at end of file
diff --git a/ue4-datasync.ps1 b/ue4-datasync.ps1
new file mode 100644
index 0000000..fc3f214
--- /dev/null
+++ b/ue4-datasync.ps1
@@ -0,0 +1,223 @@
+[CmdletBinding()] # Fail on unknown args
+param (
+    [string]$mode,
+    [string]$root,
+    [string]$src,
+    [switch]$prune = $false,
+    [switch]$force = $false,
+    [switch]$nocloseeditor = $false,
+    [switch]$dryrun = $false,
+    [switch]$help = $false
+)
+
+function Print-Usage {
+    Write-Output "Steve's UE4 Map BuiltData Sync Tool"
+    Write-Output "  Avoid storing Map_BuiltData.uasset files in source control, sync them directly instead"
+    Write-Output "Usage:"
+    Write-Output "  ue4-datasync.ps1 [-mode:]<push|pull> [[-path:]syncpath] [Options]"
+    Write-Output " "
+    Write-Output "  -mode        : Whether to push or pull the built data from your filesystem"
+    Write-Output "  -root        : Root folder to sync files to/from. Project name will be appended to this path."
+    Write-Output "               : Can be blank if specified in UE4SYNCROOT"
+    Write-Output "  -src         : Source folder (current folder if omitted)"
+    Write-Output "               : (should be root of project)"
+    Write-Output "  -prune       : Clean up versions of the data older than the latest"
+    Write-Output "  -force       : Copy ALL BuiltData files regardless of size/timestamp checks"
+    Write-Output "  -nocloseeditor : Don't close UE4 editor (this will prevent download of updated files)"
+    Write-Output "  -dryrun      : Don't perform any actual actions, just report on what you would do"
+    Write-Output "  -help        : Print this help"
+    Write-Output " "
+    Write-Output "Environment Variables:"
+    Write-Output "  UE4SYNCROOT  : Root path to sync data. Subfolders for each project name."
+    Write-Output "  UE4INSTALL   : Use a specific UE4 install."
+    Write-Output "               : Default is to find one based on project version, under UE4ROOT"
+    Write-Output "  UE4ROOT      : Parent folder of all binary UE4 installs (detects version). "
+    Write-Output "               : Default C:\Program Files\Epic Games"
+    Write-Output " "
+
+}
+
+. $PSScriptRoot\inc\ueeditor.ps1
+. $PSScriptRoot\inc\filetools.ps1
+
+$ErrorActionPreference = "Stop"
+
+
+if ($help) {
+    Print-Usage
+    Exit 0
+}
+
+if ($mode -ne "push" -and $mode -ne "pull") {
+    Print-Usage
+    Write-Output "ERROR: Mode must be 'push' or 'pull'"
+    Exit 3
+
+}
+
+if (-not $root) {
+    $root = $Env:UE4SYNCROOT
+}
+
+if (-not $root) {
+    Print-Usage
+    Write-Output "ERROR: Missing '-root' argument and no UE4SYNCROOT env var"
+    Exit 3
+}
+
+if (-not (Test-Path $root -PathType Container)) {
+    Print-Usage
+    Write-Output "ERROR: root path $root does not exist"
+    Exit 3
+}
+
+# confirm that umap files are tracked in LFS so SHAs are already there
+$lfsTrackOutput = git lfs track
+if (!$?) {
+    Write-Output "ERROR: failed to call 'git lfs track'"
+    Exit 5
+}
+$umapsOK = $false
+foreach ($line in $lfsTrackOutput) {
+    if ($line -match "^\s+\*\.umap\s+.*$") {
+        $umapsOK = $true
+        break
+    }
+}
+if (-not $umapsOK) {
+    Write-Output "ERROR: .umap files are not tracked in LFS, cannot continue"
+    Exit 5
+}
+
+# Check no changes
+git diff --no-patch --exit-code
+if ($LASTEXITCODE -ne 0) {
+    Write-Output "Working copy is not clean (unstaged changes)"
+    if ($dryrun) {
+        Write-Output "dryrun: Continuing but this will fail without -dryrun"
+    } else {
+        Exit $LASTEXITCODE
+    }
+}
+git diff --no-patch --cached --exit-code
+if ($LASTEXITCODE -ne 0) {
+    Write-Output "Working copy is not clean (staged changes)"
+    if ($dryrun) {
+        Write-Output "dryrun: Continuing but this will fail without -dryrun"
+    } else {
+        Exit $LASTEXITCODE
+    }
+}
+
+
+
+$result = 0
+
+try {
+    if ($src -ne ".") { Push-Location $src }
+
+    Write-Output "-- Sync process starting --"
+
+    # Locate UE4 project file
+    $uprojfile = Get-ChildItem *.uproject | Select-Object -expand Name
+    if (-not $uprojfile) {
+        throw "No Unreal project file found in $(Get-Location)! Aborting."
+    }
+    if ($uprojfile -is [array]) {
+        throw "Multiple Unreal project files found in $(Get-Location)! Aborting."
+    }
+
+    # In PS 6.0+ we could use Split-Path -LeafBase but let's stick with built-in PS 5.1
+    $uprojname = [System.IO.Path]::GetFileNameWithoutExtension($uprojfile)
+    if ($dryrun) {
+        Write-Output "Would sync $uprojname"
+    } else {
+        Write-Output "Syncing $uprojname"
+    }
+
+    # Close UE4 as early as possible
+    if (-not $nocloseeditor) {
+        # Check if UE4 is running, if so try to shut it gracefully
+        Close-UE-Editor $uprojname $dryrun
+    }
+
+    # Create project sync dir if necessary
+    $syncdir = Join-Path $root $uprojname
+    New-Item -ItemType Directory $syncdir -Force > $null
+    Write-Output "Sync project folder: $syncdir"
+
+    # Find all umaps which are tracked in git and get their LFS SHAs
+    $umapsOutput = git lfs ls-files -l -I *.umap
+    # Output is of the form
+    # b75b42e082ffb0deeb3fc7b40b2a221ded62872a2289bf6b63e275372849447b * Content/Maps/Subfolder/MyLevel.umap
+    foreach ($line in $umapsOutput) {
+        if ($line -match "^([a-f0-9]+)\s+\*\s+(.+)$") {
+            $oid = $matches[1]
+            $filename = $matches[2].Trim()
+
+            $subdir = [System.IO.Path]::GetDirectoryName($filename)
+            $basename = [System.IO.Path]::GetFileNameWithoutExtension($filename)
+
+            $localbuiltdata = Join-Path $subdir "${basename}_BuiltData.uasset"
+            $remotesubdir = Join-Path $syncdir $subdir
+            $remotebuiltdata = Join-Path $remotesubdir "${basename}_BuiltData_${oid}.uasset"
+
+            $same = Compare-Files-Quick $localbuiltdata $remotebuiltdata
+
+            if ($same -and -not $force) {
+                Write-Verbose "Skipping $basename, matches"
+                continue
+            }
+
+            if ($mode -eq "push") {
+                Write-Verbose "$localbuiltdata  ->  $remotebuiltdata"
+
+                # In push mode, we only upload our builtdata if there is no existing
+                # entry for that OID by default (safest). Or, if forced to do so
+                if (-not (Test-Path $localbuiltdata -PathType Leaf)) {
+                    Write-Warning "Skipping $basename, local file missing"
+                    continue
+                }
+
+                if ($dryrun) {
+                    Write-Output "Would have pushed: $basename ($oid)"
+                } else {
+                    Write-Output "Push: $basename ($oid)"
+                    New-Item -ItemType Directory $remotesubdir -Force > $null
+                    Copy-Item $localbuiltdata $remotebuiltdata    
+                }
+
+            } else {
+                Write-Verbose("$remotebuiltdata  ->  $localbuiltdata")
+                # In pull mode, we always pull if not same, or forced (checked already above)
+
+                if (-not (Test-Path $remotebuiltdata -PathType Leaf)) {
+                    Write-Warning "Skipping $basename, remote file missing"
+                    continue
+                }
+
+                if ($dryrun) {
+                    Write-Output "Would have pulled: $basename ($oid)"
+                } else {
+                    Write-Output "Pull: $basename ($oid)"
+                    New-Item -ItemType Directory $subdir -Force > $null
+                    Copy-Item $remotebuiltdata $localbuiltdata    
+                }
+
+            }
+        }
+    }
+    
+
+    Write-Output "-- Sync process finished OK --"
+
+
+} catch {
+    Write-Output "ERROR: $($_.Exception.Message)"
+    $result = 9
+} finally {
+    if ($src -ne ".") { Pop-Location }
+}
+
+
+Exit $result