Configuration

burn0 is configured via environment variables. No config files needed for basic usage.

Environment variables

Variable	Required	Default	Description
`BURN0_API_KEY`	No	—	API key for cloud mode. Get one at burn0.dev.
`BURN0_API_URL`	No	`https://api.burn0.dev`	Override the backend URL (for self-hosting or development).
`BURN0_DEBUG`	No	`false`	Set to `1` to enable debug logging.
`BURN0_ENABLE_TEST`	No	—	Set to `1` to enable tracking in `NODE_ENV=test`.

burn0 automatically detects the right mode based on your environment:

Mode	When	Behavior
dev-local	TTY + no API key	Ticker in terminal, local ledger, no cloud sync
dev-cloud	TTY + API key	Ticker in terminal, local ledger, cloud sync
prod-cloud	No TTY + API key	Silent, cloud sync only
prod-local	No TTY + no API key	Logs warning, skips tracking entirely
test-disabled	`NODE_ENV=test`	No tracking (default in tests)
test-enabled	`NODE_ENV=test` + `BURN0_ENABLE_TEST=1`	Full tracking in tests

burn0 stores data locally in the .burn0/ directory:

File	Purpose
`.burn0/config.json`	Project config (services, plans)
`.burn0/costs.jsonl`	Event ledger (last 7 days)
`.burn0/pricing-cache.json`	Cached pricing data (24h TTL)

Add .burn0/ to your .gitignore — burn0 init does this automatically.

To temporarily disable burn0 without removing the import:

# In tests (default behavior)
NODE_ENV=test npm test

# In production without API key
# burn0 automatically skips patching and logs a warning

To programmatically unpatch fetch and http:

import { restore } from '@burn0/burn0'

restore()  // Removes all burn0 patches