Softwr

Maps · head to head

GRASS GIS vs Trimble Unity Maintain

GRASS GIS logo

GRASS GIS

Maps

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

From
Free
Rated
-
Full reviewWebsite
Trimble Unity Maintain logo

Trimble Unity Maintain

Government

GIS-centric public asset and work management, the product formerly sold as Cityworks

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.; Trimble Unity Maintain esri ArcGIS is a hard prerequisite, so an organisation without it faces a second substantial licence and a GIS programme before the maintenance system can be used at all.
  • They diverge on capability: GRASS GIS covers Raster analysis, Trimble Unity Maintain covers Built on ArcGIS.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which GRASS GIS and Trimble Unity Maintain actually diverge.

Attributes where GRASS GIS and Trimble Unity Maintain differ
AttributeGRASS GISTrimble Unity Maintain
Starting priceFreeOn request
Pricing modelOpen source, no licence feequote
Free tierYesNo
PlatformsLinux, Windows, macOSWeb, iOS, Android, Windows
CategoryMapsGovernment

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

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 Trimble Unity Maintain

  • Built on ArcGIS
  • Service requests
  • Work order management
  • Permits and licensing
  • Mobile field access
  • Storeroom and inventory
  • Operational Insights
  • AgileAssets convergence

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 Trimble Unity Maintain
  • A research group building a reproducible time series analysis of satellite imagery that must be rerunnable years laternot Trimble Unity Maintain
  • An environmental agency running viewshed and solar radiation analysis for planning assessments without buying commercial GIS seatsnot Trimble Unity Maintain
  • A QGIS user who needs a specific processing algorithm that only exists in the GRASS toolboxnot Trimble Unity Maintain

Trimble Unity Maintain

  • A water utility wanting valve exercising and hydrant flushing recorded against the same GIS features the engineering team maintainsnot GRASS GIS
  • A city consolidating a citizen service request line, work orders and inspections into one location-based systemnot GRASS GIS
  • A state transportation department managing pavement and bridge assets with linear referencing rather than point assetsnot GRASS GIS
  • A public works department that has already licensed ArcGIS Enterprise and wants to avoid rekeying its asset inventorynot 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.

Trimble Unity Maintain

  • Esri ArcGIS is a hard prerequisite, so an organisation without it faces a second substantial licence and a GIS programme before the maintenance system can be used at all.
  • The product is mid-rename from Cityworks to Trimble Unity Maintain with transition timelines Trimble has not committed to publicly, leaving contracts, documentation and integrator experience split between two names.
  • CVE-2025-0994, a deserialisation flaw in Cityworks, was exploited in the wild and listed by CISA in February 2025, which makes on-premise deployments a patching obligation rather than a set-and-forget install.
  • Because assets live in the GIS, changing the asset model is a GIS division change, so maintenance teams cannot restructure their own hierarchy without another department in the loop.
  • It is built for North American public sector practice, and the permitting, funding source and reporting models do not map cleanly onto other countries or onto private industrial estates.

Pricing, plan by plan

GRASS GIS

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

Trimble Unity Maintain

On request
  • Trimble Unity Maintain$undefined/year
    • Annual subscription sized by population served, asset volume and user count
    • Esri ArcGIS Enterprise or ArcGIS Online licensing required separately
    • Hosted and on-premise deployment priced differently

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 Trimble Unity Maintain if

  • You need built on arcgis.
  • You work on Web, iOS, Android, Windows.
  • You also want service requests.
Trimble Unity Maintain review

Questions people ask

Is GRASS GIS or Trimble Unity Maintain better?
Neither clearly leads. GRASS GIS starts at Free and Trimble Unity Maintain at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, GRASS GIS or Trimble Unity Maintain?
GRASS GIS has a free tier; the other does not. Paid plans start at Free for GRASS GIS and On request for Trimble Unity Maintain.
Does GRASS GIS or Trimble Unity Maintain run on more platforms?
GRASS GIS runs on Linux, Windows, macOS. Trimble Unity Maintain runs on Web, iOS, Android, Windows.
Can I use GRASS GIS for free?
Yes. GRASS GIS has a free tier, so you can try it without paying. Trimble Unity Maintain 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 Trimble Unity Maintain is typically brought in for.
What can GRASS GIS do that Trimble Unity Maintain cannot?
GRASS GIS covers Raster analysis, Hydrological modelling, Terrain analysis, Vector topology. Trimble Unity Maintain covers Built on ArcGIS, Service requests, Work order management, Permits and licensing.

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.

Trimble Unity Maintain: Is Cityworks discontinued?

Not discontinued, renamed. It is becoming Trimble Unity Maintain, converging with AgileAssets, and Trimble has not published a final transition date.

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.

Trimble Unity Maintain: Do I need Esri ArcGIS?

Yes. The product is built on ArcGIS and cannot be deployed without an Esri licence.

GRASS GIS: Do I need to use its interface?

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

Trimble Unity Maintain: Was there a security incident?

Yes. CVE-2025-0994 in Cityworks was exploited in the wild and added to the CISA known exploited vulnerabilities catalogue in February 2025.

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.

Trimble Unity Maintain: Can it handle roads and pavement as well as pipes?

Yes, through the AgileAssets lineage now inside the Unity Maintain family, which adds linear referencing for transportation assets.

Share

Related pages

More on GRASS GIS

More on Trimble Unity Maintain

Keep looking

Other head to heads