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Maps · head to head

GRASS GIS vs What3words

GRASS GIS logo

GRASS GIS

Maps

Long-running open source geospatial analysis engine for raster, vector and terrain processing

From
Free
Rated
-
Full reviewWebsite
What3words logo

What3words

Maps

What3words has divided the world into 3m squares and given each one

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only GRASS GIS has a free tier, so it costs nothing to try first.
  • Each has a real cost: GRASS GIS the location and mapset data model requires importing data into a structured database with a fixed coordinate system before analysis, which is a real barrier for anyone used to opening files directly.; What3words the free API plan includes no coordinate conversion, only AutoSuggest, and is rate limited to 5 requests per second
  • They diverge on capability: GRASS GIS covers Raster analysis, What3words covers Core Functionality.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which GRASS GIS and What3words actually diverge.

Attributes where GRASS GIS and What3words differ
AttributeGRASS GISWhat3words
Starting priceFreeOn request
Pricing modelOpen source, no licence feefreemium
Free tierYesNo
PlatformsLinux, Windows, macOSWeb

Identical on both: user rating (Not yet rated), category (Maps).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in GRASS GIS

  • Raster analysis
  • Hydrological modelling
  • Terrain analysis
  • Vector topology
  • Temporal framework
  • Image processing
  • Python API
  • QGIS integration

Only in What3words

  • Core Functionality
  • User Interface

What people use each for

The jobs each tool is most often brought in to do.

GRASS GIS

  • A hydrologist delineating watersheds and modelling flow accumulation over a large digital elevation modelnot What3words
  • A research group building a reproducible time series analysis of satellite imagery that must be rerunnable years laternot What3words
  • An environmental agency running viewshed and solar radiation analysis for planning assessments without buying commercial GIS seatsnot What3words
  • A QGIS user who needs a specific processing algorithm that only exists in the GRASS toolboxnot What3words

What3words

  • Referring to a 3 metre square location with three wordsnot GRASS GIS
  • Adding location entry to a delivery or dispatch appnot GRASS GIS
  • Converting between coordinates and what3words addresses via APInot GRASS GIS

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

GRASS GIS

  • The location and mapset data model requires importing data into a structured database with a fixed coordinate system before analysis, which is a real barrier for anyone used to opening files directly.
  • The native graphical interface is dated and inconsistent compared with QGIS or ArcGIS, so most users end up running GRASS through QGIS and never learn the tool they are actually depending on.
  • There is no vendor, so contractual support, service levels and liability do not exist by default and must be arranged with an independent consultancy that may not cover your jurisdiction.
  • Cartographic output and map layout are weak relative to the analysis capability, meaning a second tool is always needed to produce a publishable map.
  • Module naming and argument conventions are idiosyncratic and long-standing, so scripts are durable but the learning curve is steep and transferable skills from other GIS packages help less than expected.

What3words

  • The free API plan includes no coordinate conversion, only AutoSuggest, and is rate limited to 5 requests per second
  • Converting to and from what3words addresses starts on the Basic plan at $9.99 per month for 1,000 conversions
  • Priority and developer support require the Standard plan at $45 per month
  • 24/7 phone support requires the Plus plan at $125 per month
  • Custom invoicing and annual payment require the Premium plan at $300 per month
  • Overage pricing is not published; the page states only that a fair usage policy applies
  • The three word address scheme is proprietary and licensed rather than open data

Pricing, plan by plan

GRASS GIS

Free
  • GRASS GISFree
    • GNU GPL licence
    • All modules included
    • No user or seat limits

What3words

On request

No published plan breakdown. See the What3words review.

Which should you pick?

Choose GRASS GIS if

  • You need raster analysis.
  • You want to start without paying.
  • You work on Linux, Windows, macOS.
  • You also want hydrological modelling.
GRASS GIS review

Choose What3words if

  • You need core functionality.
  • You also want user interface.
What3words review

Questions people ask

Is GRASS GIS or What3words better?
Neither clearly leads. GRASS GIS starts at Free and What3words at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, GRASS GIS or What3words?
GRASS GIS has a free tier; the other does not. Paid plans start at Free for GRASS GIS and On request for What3words.
Does GRASS GIS or What3words run on more platforms?
GRASS GIS runs on Linux, Windows, macOS. What3words runs on Web.
Can I use GRASS GIS for free?
Yes. GRASS GIS has a free tier, so you can try it without paying. What3words starts at On request.
What is GRASS GIS best used for?
GRASS GIS is most often used for a hydrologist delineating watersheds and modelling flow accumulation over a large digital elevation model, a research group building a reproducible time series analysis of satellite imagery that must be rerunnable years later, an environmental agency running viewshed and solar radiation analysis for planning assessments without buying commercial gis seats, a qgis user who needs a specific processing algorithm that only exists in the grass toolbox. Of those, a hydrologist delineating watersheds and modelling flow accumulation over a large digital elevation model and a research group building a reproducible time series analysis of satellite imagery that must be rerunnable years later are not what What3words is typically brought in for.
What can GRASS GIS do that What3words cannot?
GRASS GIS covers Raster analysis, Hydrological modelling, Terrain analysis, Vector topology. What3words covers Core Functionality, User Interface.

Answered from the vendors’ own pages

GRASS GIS: Who maintains GRASS GIS?

An international volunteer and academic developer community under the Open Source Geospatial Foundation. It originated at the US Army Construction Engineering Research Laboratory in 1982.

GRASS GIS: Can I buy commercial support?

Not from a vendor. Independent consultancies in the OSGeo ecosystem offer paid support and development, and availability varies by region.

GRASS GIS: Do I need to use its interface?

No. Most people run GRASS algorithms through the QGIS processing toolbox or from Python.

GRASS GIS: Is it suitable for production use?

Yes for analysis pipelines, and it is used by agencies and research institutions. Plan for community support rather than a service level agreement.

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