/Logging

Understanding Log Levels and When to Use Each

A practical guide to debug, info, warn, error, and fatal log levels.

The Five Log Levels

Lognitor supports five log levels, from least to most severe:

Level	When to Use
`debug`	Detailed diagnostic information. Use during development or when debugging specific issues. Not recommended for production unless investigating a problem.
`info`	Normal operational events. Server started, user signed up, order created, request completed. The most commonly used level.
`warn`	Something unexpected but not broken. Rate limit approaching, deprecated API used, slow query detected, retry succeeded.
`error`	Something failed. Payment declined, API call timeout, database connection lost. The operation did not complete as expected.
`fatal`	The application cannot continue. Database corrupted, out of memory, critical config missing. Usually followed by a shutdown.

Examples

JavaScript

Lognitor.debug('Cache miss', { metadata: { key: 'user:123' } });
Lognitor.info('Order created', { metadata: { orderId: 'ord_456', total: 99.99 } });
Lognitor.warn('Rate limit at 85%', { metadata: { usage: 850, limit: 1000 } });
Lognitor.error('Payment failed', { error: new Error('Card declined') });
Lognitor.fatal('Database corrupted, shutting down');

Filtering by Level

Use the minLevel config option to control which levels are sent:

JavaScript

Lognitor.init({
  apiKey: 'your-key',
  minLevel: 'info', // Drops debug logs, sends info and above
});

Production recommendation

Set minLevel: 'info' in production. Enable debug only when investigating specific issues to avoid log volume spikes.