OM Core is an open-source reference implementation of a multidimensional modeling engine for structured financial, operational, and analytical models.

Instead of treating the spreadsheet grid as the model, OM Core represents the model using dimensions, cubes, groups, and rules. Grids and views are projections of that model, not the source of truth.

Alpha software: OM Core is under active development. APIs, command names, file formats, GUI behavior, and module boundaries may change before v1.0.

The main documentation site is here:

https://cloudcell.github.io/om-docs/

Start with:

Most spreadsheet models mix several things together:

• model structure
• business logic
• layout
• presentation
• calculation flow
• user interaction

OM Core separates these concerns.

The model is built from:

• Dimensions — business axes such as Time, Account, Region, Product, Scenario, or Line Item.
• Cubes — data stored over one or more dimensions.
• Groups and hierarchies — structured collections and rollups.
• Rules — calculations expressed over semantic model addresses instead of spreadsheet coordinates.
• Views — grids and interfaces for inspecting and interacting with the model.

A rule should describe the business relationship, not the cell location. For example, a model should be able to express a relationship such as gross margin being derived from revenue and cost without making that relationship depend on a particular row, column, or copied formula.

This repository currently contains the full alpha application stack required to run OM Core.

That includes the modeling engine and supporting command, REPL, GUI/TUI, runtime, timeline, scripting, plugin, storage-adapter, examples, and test layers.

Some modules are internal implementation layers. They are included because the current alpha application depends on them. They should not yet be treated as stable public extension APIs.

The .om/ directory is intentionally committed.

It contains default OM Core application configuration, including toolbar settings required by the current alpha application. It is not a temporary cache directory or private local state.

Do not delete .om/ unless the application configuration system has been changed to load these defaults from another documented location.

OM Core currently runs from source.

git clone https://github.com/cloudcell/om-core.git
cd om-core
./start.sh

Use PowerShell:

git clone https://github.com/cloudcell/om-core.git
cd om-core
.\start.ps1

./start.sh or .\start.ps1 starts the GUI and asks whether to open a TUI in a separate terminal.

OM Core uses uv to manage its Python environment. Install uv, then run uv sync in the project root to create .venv and install dependencies. After that, the start scripts and test scripts use uv run automatically.

You can also start specific runtime modes:

# Linux / macOS
./start.sh --gui       # graphical interface only
./start.sh --tui       # terminal interface in the current terminal
./start.sh --runtime   # headless runtime only
./start.sh --repl      # REPL command shell in the current terminal

# Windows
.\start.ps1 --gui       # graphical interface only
.\start.ps1 --tui       # terminal interface in the current terminal
.\start.ps1 --runtime   # headless runtime only
.\start.ps1 --repl      # REPL command shell in the current terminal

For more detail, see the installation guide:

https://cloudcell.github.io/om-docs/start/installation/

Running ./start.sh (Linux / macOS) or .\start.ps1 (Windows) launches the GUI. You will be prompted to open a TUI in a separate terminal; accepting the default (Y) gives you a command shell alongside the GUI, as shown below.

Note: The first time you run ./start.sh or .\start.ps1, uv will create a Python virtual environment in the project folder (.venv) and install dependencies from uv.lock.

After starting OM Core, try the built-in help command:

You can ask for help on specific topics:

om> help rule
om> help calc

A minimal OM Core script looks like this:

# Dimensions
dim Month Jan Feb Mar

# Cube
cube Sales Month

# View
view SalesView = Sales::Month

# Rules
rule Sales::Month.Jan = 100
rule Sales::Month.Feb = Sales::Month.Jan * 1.1
rule Sales::Month.Mar = Sales::Month.Feb * 1.1

# Calculate
calc

Save that as hello.openm, then source it from the REPL or TUI:

For the full walkthrough, see:

https://cloudcell.github.io/om-docs/start/quickstart/

Run the test suite with the platform-specific script:

# Linux / macOS
./test.sh

OM Core is split into a session-scoped runtime layer, a command/query service layer, and multiple clients. The engine owns the canonical workspace state; the GUI, TUI, REPL, and CLI are clients that communicate through the message bus.

Spreadsheets are fast and flexible, but large models often become fragile because business logic is encoded in cell addresses, copied formulas, linked tabs, and implicit layout conventions.

OM Core uses a different level of abstraction. It makes the model explicit: dimensions describe the axes, cubes hold values, groups organize structure, rules define calculations, and views display the result.

The tradeoff is deliberate: you define more structure up front, and in return the model becomes easier to audit, extend, test, and maintain as it grows.

For the longer explanation, see:

https://cloudcell.github.io/om-docs/start/why-not-spreadsheets/

OM Core is currently alpha software.

Not yet promised before v1.0:

• stable public API
• stable plugin API
• stable scripting API
• stable file format
• packaged desktop installer
• production readiness for critical business use without independent validation

See also:

• KNOWN_ISSUES.md
• CHANGELOG.md
• SECURITY.md

OM Core is distributed under the GNU Affero General Public License v3.0 unless otherwise stated.

See:

• LICENSE
• NOTICE
• legal/THIRD-PARTY-NOTICES.md
• legal/CONTRIBUTOR-CLA.md
• legal/CONTRIBUTOR-SIGNOFFS.md

The OM Core name is governed separately from the software license.

See:

Contributions are welcome, especially small, focused improvements to examples, documentation, and clearly scoped engine behavior.

Please read:

• CONTRIBUTING.md
• legal/CODE_OF_CONDUCT.md
• SECURITY.md

Security issues should not be reported through public GitHub issues. See SECURITY.md.