GeoTIFF Viewer
Open GeoTIFF and Cloud Optimized GeoTIFF (COG) files in your browser. Inspect metadata, the coordinate system and pixel values; view elevation models with hillshade and draw profiles.
A file you pick from your computer is read inside the browser and is not uploaded anywhere. For a COG opened by URL, pixel data is requested directly from that server. Basemaps come from Esri and OpenStreetMap servers. If you have accepted cookies, only events such as "file opened" are counted anonymously.
What it reads
Uncompressed, LZW, Deflate, PackBits, JPEG and WebP compressed; stripped or tiled; 8 to 64-bit integer and floating-point GeoTIFF files. Click the raster on the map to read a pixel value.
Related Tools
What a GeoTIFF is and what this tool does
A GeoTIFF is a regular TIFF image with location information added. Besides the pixels, the file stores the coordinate system of the image (as GeoKey tags), the coordinate of the top-left corner and the pixel size. Orthophotos, satellite imagery, digital elevation models (DEMs), classified land cover maps and analysis outputs are usually shared in this format. A Cloud Optimized GeoTIFF (COG) is the same format arranged so that a server can deliver it piece by piece.
This tool is meant for a quick look inside a tif file without installing desktop GIS software. It lists the size, band count, data type, NoData value, pixel size, extent, coordinate system, compression and whether overviews are present; places the image in the right position on the map, reads the value of the pixel you click, and computes a histogram and basic statistics.
How to use it
- Drag the file onto the box above, or click the box to choose it. If the file is published as a COG on a server, paste its address into the URL box and press Open.
- Check the coordinate system and extent in the metadata table. If the coordinate system cannot be read from the file or is wrong, enter an EPSG code (for example 32635) or a proj4 definition and press Apply.
- For single-band files, choose a colour ramp and a stretch method. On elevation models, hillshade adds relief shading; vertical exaggeration brings out landforms in flat terrain.
- For multi-band images, switch to RGB and assign any band to the red, green and blue channels. In a Sentinel-2 file, for example, putting the near-infrared band on the red channel highlights vegetation.
- Click the raster on the map to see that pixel's value in every band, its row and column, and its coordinates.
- For an elevation profile, press Draw a profile line, click the vertices on the map and click the last point again to finish. The profile chart and the total ascent and descent are computed, and you can download the values as CSV.
- Save the current rendering as PNG. The .pgw file downloaded with it carries the image's position in the source coordinate system.
Display options
Stretch decides which range of raw values is mapped to the two ends of the colour ramp. The 2% - 98% percentile option leaves out the lowest and highest two percent, so a few outlier pixels do not wash out the whole image. Minimum - maximum uses the full range, and Custom lets you type the low and high values yourself. The dashed lines on the histogram mark the selected range.
Hillshade derives each pixel's slope and aspect from its eight neighbours and lights the surface from the northwest (315°) at an altitude of 45°. The result is blended over the colour ramp. For classified rasters that carry a colour palette (land cover, for instance), the colours stored in the file are used as they are.
Data and method
The file is read in the browser with geotiff.js 2.1.3 (MIT licence). For large files only the required parts are read: for display and statistics, a suitable overview is chosen so that the longest side does not exceed 2,048 pixels, and without overviews the data is read in blocks and downsampled. The value of a clicked pixel is always read from the full-resolution image.
The coordinate system is taken from the GeoKey tags in the file and transformed with proj4js 2.9.0 (MIT licence). Because the map uses Web Mercator, the raster is resampled by inverse mapping: for each screen pixel of the map layer, the matching position in the source coordinate system is found and the colour of the nearest source pixel is taken. The transformation is computed exactly on an 8-pixel grid and interpolated linearly in between. For files in the ED50 datum, the EPSG:1784 (ED50 to WGS 84 (30)) parameters defined for Turkey are used.
Icons are from Lucide (ISC). Basemaps belong to Esri and OpenStreetMap contributors. The sample image is read from the open Sentinel-2 archive on AWS and contains Copernicus Sentinel-2 data. Open-source libraries used and their licences: Data Sources.
Accuracy limits
- Approximate statistics: For large files the histogram and statistics come from an overview or a downsampled sample. The tool says so in a note; exact figures require a full-resolution computation.
- Profile resolution: Profile values are taken from the on-screen display grid. If the file was read at reduced resolution, narrow valleys and ridges are smoothed.
- Coordinate system: EPSG codes not built into the tool need a proj4 definition. Older systems that require a datum shift can be off by a few metres.
- Not supported: External .ovr overview files, .aux.xml sidecar files and JPEG 2000 are not read. Some LERC and ZSTD compressed files may not open.
- Opening by URL: The server must send a CORS header and support HTTP Range requests. Addresses that do not meet these conditions are blocked by the browser.
For professional projects
If your team processes satellite or drone imagery on a regular basis, or needs raster workflows built into its own systems, you can reach us through the contact page. More about our work is on the Rodosto Teknoloji website.
Frequently Asked Questions
What is the difference between a COG and a regular GeoTIFF?
A Cloud Optimized GeoTIFF (COG) is an ordinary GeoTIFF whose internal layout follows a few rules: pixel data is split into tiles, reduced-resolution copies (overviews) are stored inside the file, and the header sits at the start. An application can therefore read just the part it needs without downloading the whole file. Regular GeoTIFFs open in this tool too; the difference shows up as speed and memory use with large files.
Is my file uploaded to a server?
No. A file you pick from your computer is read inside the browser and is not sent anywhere. If you open a COG by URL, the pixel data is requested directly from the server at that address. Basemap tiles come from Esri and OpenStreetMap servers, and if you choose to fetch a coordinate system definition from epsg.io, only the EPSG code is sent there.
What should I do if the image appears in the wrong place on the map?
Check the coordinate system in the metadata table first. The file may carry a wrong EPSG code, or none at all. If you know the correct code, type it into the coordinate system box and press Apply; the image is placed again. With older datums such as ED50, a shift of a few metres can come from the datum transformation parameters in use.
Can I open very large GeoTIFF files?
If the file has overviews, even files of several gigabytes can be opened, because only a suitable reduced copy is read for display. Without overviews all pixel data has to be scanned, which can be slow and may hit the browser's memory limit. The tool shows a notice for files larger than 200 MB.