> For the complete documentation index, see [llms.txt](https://codifi-fdm.gitbook.io/codifi-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://codifi-fdm.gitbook.io/codifi-docs/web-app/map-setup-and-offline-areas/map-overlays.md).

# Map Overlays

<figure><img src="https://3544178300-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FJ8P3pqhxdFwQkIOjOUut%2Fuploads%2FMB5hiQKK18l3k4hmDeX6%2FMap%20Overlays.png?alt=media&amp;token=c231df84-1cc7-4fb9-a243-8a5bc5446c99" alt="" width="375"><figcaption></figcaption></figure>

**Map Overlays** in Codifi let you upload and display custom GeoJSON files directly on your Project maps. Use them to visualize historic boundaries, planned transects, parcel data, environmental features, hazard zones — anything spatial that gives your field crew context but isn't itself a Codifi Record.

Overlays carry their source GeoJSON's attribute data, support flexible styling (from one-click colors to data-driven Mapbox expressions), and sync across web and mobile platforms — including offline, so your team has the same view in the field as in the office.

***

## What's in This Section

| Page                                                                                                                      | What it covers                                                                                                      |
| ------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
| [Adding Map Overlays](/codifi-docs/web-app/map-setup-and-offline-areas/map-overlays/adding-map-overlays.md)               | Uploading a GeoJSON file to your Project and what Codifi does with it                                               |
| [Styles](/codifi-docs/web-app/map-setup-and-offline-areas/map-overlays/styles.md)                                         | Customizing how an overlay looks on the map — Simple Styles for everyday use, Advanced Styles for data-driven cases |
| [Viewing Overlays on Mobile](/codifi-docs/web-app/map-setup-and-offline-areas/map-overlays/viewing-overlays-on-mobile.md) | Toggling overlay visibility, adjusting transparency, and using overlays in the field                                |

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## Quick Tips Before You Upload

* **One geometry type per file.** Each GeoJSON should be points, lines, **or** polygons — not a mix. If your source has mixed geometries, split them into separate files (`points.geojson`, `lines.geojson`, `polygons.geojson`) before uploading. This makes styling much cleaner later.
* **Use WGS84 (EPSG:4326) coordinates.** If your overlay lands in the middle of the ocean after upload, your source was projected — re-export from your GIS tool in WGS84 lat/lon.
* **Name overlays clearly.** A name like "Planned Transects 2026" is much easier for field crews to recognize than the raw filename — rename overlays right after upload.
* **Style for satellite imagery.** Codifi mobile defaults to satellite basemap. Bright fills with dark stroke colors stay readable; saturated greens and blues disappear into vegetation and water.

***

## See Also

* [Project Map Extent](/codifi-docs/web-app/map-setup-and-offline-areas/project-map-extent.md) — frame the Project area first; overlays sit inside it
* [Offline Areas](/codifi-docs/web-app/map-setup-and-offline-areas/offline-areas.md) — overlays are bundled into offline area downloads automatically