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Tile Converter

Prepare big rasters and tile archives for DropMaps — convert GeoTIFF and MBTiles to stream-ready COG and PMTiles, locally.

The DropMaps Converter is a small, free desktop app that prepares large rasters and tile archives for DropMaps. It turns ordinary GeoTIFFs and MBTiles into the cloud-streaming formats the web app reads best — Cloud-Optimized GeoTIFF (COG) and PMTiles — right on your own machine, with no upload and no file-size ceiling.

What it does

  • GeoTIFF / TIFF → COG — adds internal tiling and overviews (and reprojects if needed) so big rasters and drone orthomosaics stream fast in DropMaps. COG keeps the original bands, so you can still restyle imagery and single-band data in the app.
  • MBTiles → PMTiles — repacks an MBTiles archive into a single portable PMTiles file (no re-rendering).
  • PMTiles output (opt-in) — for visual/RGB overlays you can choose PMTiles instead of COG.
  • Runs locally — everything converts on your computer. Nothing is uploaded, and there’s no file-size limit, so it handles multi-gigabyte rasters the in-browser tools can’t. Output files are written next to the source.

Why convert?

DropMaps streams COG and PMTiles over the web via HTTP range reads, so only the part of the map you’re looking at is fetched. Converting a plain GeoTIFF to COG (or an MBTiles to PMTiles) up front means the layer loads quickly in the browser and can be backed up to the cloud and streamed to your other devices. See Supported formats for how each format is read.

Get the Converter

Signed installers for Windows, macOS and Linux are on the way — see the Tools page for downloads. It’s free, needs no account, and works offline once installed.

In the meantime, files that are already COG or PMTiles can be dropped straight into the app — no conversion needed.

Good to know

  • Conversion is local and free — there’s no server cost, so there’s no file-size cap.
  • A raster needs a coordinate system to be placed on the map. If a GeoTIFF relies on sidecar files (.prj, .tfw/.wld), keep them in the same folder as the .tif.
  • COG is the default for rasters because it preserves bands and stays close to the original size; PMTiles bakes in RGB and is best reserved for visual overlays.

Next steps