Mailchimp Open Commerce, formerly Reaction Commerce, is an API-first, headless commerce platform built on Node.js, MongoDB, and GraphQL for development teams that want to run a custom storefront, marketplace, or multi-shop operation on their own infrastructure — and the project has been discontinued.

What it is

Mailchimp Open Commerce is an open-source commerce backend written in JavaScript and licensed under GPL-3.0. It is distributed through the Node.js ecosystem rather than as a hosted product: the README states that it plays nicely with npm, Docker, and Kubernetes, and MongoDB is the datastore behind its GraphQL API. The repository is reactioncommerce/reaction, with a separate command-line tool maintained at reactioncommerce/cli; the project has accumulated 12,398 stars, 2,177 forks, and 96 open issues, with the most recent push recorded on 2026-03-01. Its topic list places it squarely in headless commerce: cart, commerce, e-commerce, ecommerce-platform, headless, graphql, javascript, mongodb, docker, and marketplace. It ships an admin system alongside the API, and the README presents API, Admin, and Storefront projects as separate things a team creates and works with independently.

The concrete problem it solves is owning the commerce layer of a shop instead of assembling one or renting it. A team that needs cart, catalog, inventory, shipping rates, tax tables, fulfillment methods, order tracking, and transactional emails would otherwise build those subsystems from scratch or hand the whole layer to a vendor. Open Commerce supplies them as a headless GraphQL backend that a custom frontend can query, and it names "Open — Fully open source. Never be locked in again" as one of its features, framing the project as an escape from vendor lock-in rather than as a hosted service. Because the backend is separate from presentation, the storefront and the admin can each be replaced without touching the commerce core.

Key capabilities

• API-first, headless architecture built on Node.js, MongoDB, and GraphQL, with API, Admin, and Storefront projects developed separately through the CLI.
• Composable plugin system: a flexible set of integrations can be selected per installation, and new plugins are scaffolded with reaction create-plugin api into the custom-packages directory.
• Multi-tenant hosting, allowing multiple shops to run from the same installation.
• Product modelling with options and variants, plus inventory tracking that permits or disallows backorders.
• Shipping and tax handling through either a third-party rate provider or a custom-built table, and a flexible fulfillment system for custom fulfillment methods.
• Order tracking and management inside the included admin system, with customizable email templates for order confirmations.
• Deployment via npm, Docker, and Kubernetes, scaling from a single server to hundreds; the README claims sites running tens of thousands of orders per day with hundreds of thousands of products.

Who uses it and how

• High-volume merchants: the README positions the platform for sites handling tens of thousands of orders per day and hundreds of thousands of products, where query speed affects page speed.
• Multi-tenant operators running several shops from one Open Commerce installation rather than one deployment per brand.
• Frontend and storefront teams that treat Open Commerce purely as a GraphQL backend and build their own client against it.
• Plugin authors who add integrations to an existing installation by creating a package under custom-packages and restarting the server.
• Core platform developers working inside the reaction monorepo, using pnpm and Docker Compose to run the server and MongoDB locally.

Getting started

The README's recommended path for a project built on Open Commerce is the CLI: create the project, run npm install, then start it with reaction develop api, which launches the Open Commerce GraphQL server and MongoDB. Working on the core itself requires pnpm, Docker, and Docker Compose, then cloning reactioncommerce/reaction, running pnpm install, and copying apps/reaction/.env.example to apps/reaction/.env.

How it compares

No list of paid products that Open Commerce replaces is provided in the facts. No comparable headless commerce project is named in the supplied description or topic list either, so on this registry it stands alone rather than sitting in a documented field of alternatives.

When to use it — and when not to

Adopting it means operating your own stack: MongoDB, a Node.js runtime at 14.18.1 or above, and Docker with Docker Compose and pnpm if you intend to work on core plugins. The decisive limitation is upstream status — the repository description states plainly that the project has been discontinued, so a team picking it up should expect no further fixes from the maintainers and should weigh the 96 open issues accordingly. GPL-3.0 is also a copyleft licence, which matters if the plan is to ship a modified version under different terms. Anyone who needs a maintained platform with vendor support, or who does not want to run a database and container infrastructure, should choose something else.

Install the project dependencies:

Finally, start the server in development mode:

Note: Optionally, from within the project-directory you may issue the above command without mentioning the project type and the CLI would check your package.json for the "projectType" and pick it up from there. This expects that the project itself was built using the latest version of the CLI as explained in the above steps.

Example, instead of the above command, you may skip mentioning 'api' and just use:

This will start the Open Commerce GraphQL server and Mongo Server. Press Ctrl+C to stop.

- A sample custom plugin has been installed, and you should see its output in the logs. (Your Sample Plugin)
- To add a new plugin based on our plugin template run:

Validate whether the plugin was created in the `custom-packages`

You now need to change back up to the root:

now you can run:

This plugin will now be loaded the next time you start Open Commerce.

### Congratulations!! You're ready to start developing with Open Commerce

See the [Complete CLI instructions](https://github.com/reactioncommerce/cli) for how to create your local storefront and admin.


Go to the complete [installation instructions](https://mailchimp.com/developer/open-commerce/guides/quick-start/#access-the-dashboard-playground-and-storefront) to see how to set up your store

# API development
If you are working on core plugins (not developing plugins for your own installation) you should follow these 
instructions

## What you need

- [pnpm](https://pnpm.io/)
- [Docker](https://www.docker.com/get-started/)
- [Docker Compose](https://docs.docker.com/compose/)

## Install PNPM
```bash
npm i -g [email protected]

git clone https://github.com/reactioncommerce/reaction.git
cd reaction
pnpm install
cp apps/reaction/.env.example apps/reaction/.env

## you must change MONGO_URL in the .env to mongodb://localhost:27017/reaction before start
pnpm run start:dev

docker-compose up -d
pnpm run start:dev