What are Runtimes?
Runtimes are secure, isolated execution environments that power Reactors and Proxy Transforms, allowing your custom code to process sensitive data without it touching your systems.
Runtime Comparison
Basis Theory supports the following runtime families:
| Feature | node-bt | Node.js Runtime Images |
|---|---|---|
| Images | node-bt | node22, node24 |
| Node.js Version | 16 | 22 or 24 |
| Provisioning | Synchronous | Asynchronous |
| Dependencies | Whitelist only | Any npm package |
| Timeout | Fixed | Configurable |
| Resources | Fixed | Configurable |
| Warm Instances | Default only | Configurable |
| Permissions | Via a linked Application | Declared on the runtime |
| Runtime Logs | Deprecated CLI live logs | Portal History/Live, CLI read/tail, and Webhook records |
| Vulnerability Scanning | Managed for whitelisted dependencies | Deployment and continuous scanning |
node-bt runtime is deprecated. Use a Node.js runtime image for new Reactors and Proxy code transforms. Migrate away from the node-bt runtime as soon as possible to avoid disruption.node-bt
The legacy node-bt runtime uses Node.js 16 and a curated set of dependencies. Existing resources remain available.
Learn more about node-bt or follow Migrate from node-bt.
Node.js Runtime Images
The available Node.js runtime images have the same runtime options, provisioning states, code contracts, and security controls. Choose the image that matches the Node.js version used to develop and test your code.
Learn more about Node.js Runtime Images.
Runtime Logs
Supported Node.js runtime images capture structured application and lifecycle records when logging is enabled. Inspect individual records with Portal History/Live or CLI logs read/logs tail, or consume Webhook batches. See Runtime Logs for capture configuration, access, search, and limitations. Existing node-bt workflows retain access to deprecated CLI live logs.
Vulnerability Scanning
For deployment-time and continuous vulnerability scanning behavior, notification cadence, and webhook events, see Runtime Vulnerability Scanning.
Choosing a Runtime
| Scenario | Recommended Runtime Image |
|---|---|
| New Reactors and Proxy code transforms | A Node.js runtime image |
Existing node-bt code | Follow Migrate from node-bt |
| Custom dependencies | A Node.js runtime image |
| Configurable resources | A Node.js runtime image |