What are the best free catastrophe modeling software options for analyzing accumulation by peril and region?

Here are the best free or open-source options for catastrophe modeling when your goal is accumulation analysis by peril and region. The “best” choice depends on whether you want a full cat-model workflow, hazard-focused analysis, or portfolio accumulation dashboards.

Best free options

1. OpenQuake

Best overall free catastrophe-risk platform

• What it does: Open-source risk engine from the Global Earthquake Model Foundation
• Perils: Strongest for earthquake, also supports flood, wind, and other hazards through models/workflows
• Good for: Exposure aggregation, loss modeling, scenario analysis, hazard maps, regional accumulation
• Strengths:
  • Mature and widely used
  • Handles portfolio-level loss aggregation
  • Can break down by region, taxonomy, occupancy, peril, return period
  • Comes with a web UI and APIs
• Limitations:
  • Setup can be technical
  • Best support is for supported openquake-compatible hazard/risk inputs
• Best if: You want the closest thing to a free professional cat-modeling engine

2. CLIMADA

Best for multi-peril climate and natural hazard accumulation

• What it does: Open-source Python platform for climate and catastrophe risk assessment
• Perils: Flood, windstorm, tropical cyclone, wildfire, drought, heat, sea level rise, and more depending on data/model choice
• Good for: Event-based accumulation, vulnerability/loss estimation, regional aggregation, climate-conditioned risk
• Strengths:
  • Very flexible for multi-peril work
  • Good for scenario analysis and portfolio exposure
  • Python-based, so easy to integrate with data science workflows
• Limitations:
  • Less “turnkey” than commercial tools
  • Requires scripting and good data preparation
• Best if: You want broad peril coverage and are comfortable in Python

3. Oasis LMF / Oasis Loss Modelling Framework

Best for exposure/loss aggregation and model interoperability

• What it does: Open-source loss modeling framework focused on standardized catastrophe model workflows
• Perils: Depends on available model components; commonly used for catastrophe loss modeling across multiple perils
• Good for: Structured event loss calculation, portfolio accumulation, model modularity
• Strengths:
  • Designed for catastrophe model workflows
  • Useful for portfolio accumulation by geography/peril
  • Strong for interoperability and custom models
• Limitations:
  • More framework than out-of-the-box modeling app
  • You may need to build or source hazard/vulnerability components
• Best if: You want to assemble or run structured cat workflows rather than use a single ready-made app

4. R packages / Python libraries for hazard accumulation

Best for lightweight, custom analysis

Examples:

• Python: pandas, geopandas, xarray, numpy, scipy, rasterio, shapely

• R: terra, sf, dplyr, ggplot2

• What they do: Not cat-modeling software by themselves, but great for custom accumulation analysis

• Good for: Summarizing exposure by region, peril stacking, map-based aggregation, spatial joins

• Strengths:

  • Fully free
  • Highly flexible
  • Great for reporting and BI-style accumulation

• Limitations:

  • You must build the modeling logic yourself

• Best if: You mainly need accumulation reporting rather than a full catastrophe engine

5. QGIS

Best free GIS front end for region-based accumulation mapping

• What it does: Open-source GIS platform
• Perils: Not a cat model itself, but useful for spatial accumulation analysis
• Good for: Mapping exposure, joins by admin region, peril zones, overlays, heat maps
• Strengths:
  • Very useful for regional aggregation workflows
  • Easy to visualize accumulation by peril and region
• Limitations:
  • No built-in catastrophe loss engine
• Best if: You need the GIS side of catastrophe accumulation

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Quick recommendations by use case

If you want a full free cat-modeling engine

• OpenQuake

If you want multi-peril climate/cat accumulation in Python

• CLIMADA

If you want a modular loss-modeling framework

• Oasis LMF

If you just want region/peril accumulation reporting

• QGIS + Python/R

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What to look for in a free catastrophe modeling tool

For accumulation by peril and region, make sure the software supports:

• Spatial exposure aggregation by country, state, county, CRESTA, grid, or custom polygons
• Peril tagging so you can separate flood vs wind vs quake vs wildfire
• Scenario/event catalogs for event-based accumulation
• Return period / exceedance metrics if needed
• Geocoding and GIS integration
• Portfolio rollups and loss summaries
• Open data compatibility for hazard footprints, vulnerability curves, and exposure data

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Practical note

If your main objective is accumulation by peril and region, a common free stack is:

• QGIS for geospatial preparation and mapping
• Python (pandas/geopandas) for aggregation and reporting
• OpenQuake or CLIMADA for the actual hazard/loss modeling

If you want, I can also give you:

1. a feature-by-feature comparison table,
2. the best tool for specific perils like flood/wind/earthquake, or
3. a recommended free workflow for accumulation analysis from exposure data to regional loss summaries.