Why Choose @sylphx/cat?

@sylphx/cat is the fastest, lightest, and most extensible logger for all JavaScript runtimes. Built for modern applications with performance, security, and observability in mind.

Comparison with Other Loggers

Feature	@sylphx/cat	Pino	Winston
Bundle Size	8.93 KB	11 KB	80 KB
Performance	25M ops/s	15M ops/s	5M ops/s
Zero Dependencies	✅	❌	❌
Universal Runtimes	✅	❌	❌
OpenTelemetry OTLP	✅	Partial	❌
W3C Trace Context	✅	❌	❌
OWASP 2024 Compliant	✅	❌	❌
Tail-Based Sampling	✅	❌	❌
TypeScript-First	✅	✅	⚠️
Tree-Shakable	✅	Partial	❌

Key Benefits

⚡ Blazing Fast Performance

25M+ operations per second with optimized hot paths:

// Fast-path level filtering - 234M ops/sec
logger.debug('This is filtered out') // Logger level is 'info'

// Basic logging - 21M ops/sec
logger.info('Basic log message')

// Structured logging - 18M ops/sec
logger.info('User action', { userId: '123', action: 'login' })

Performance optimizations:

• Fast-path level filtering
• Minimal object allocation
• Optional batching for high throughput
• Zero dependencies for minimal overhead

🪶 Ultra Lightweight

8.93 KB gzipped, smaller than competitors despite having more features:

• Core only: ~5 KB (basic logging)
• Full featured: 8.93 KB (all plugins, transports)
• Tree-shakeable: Import only what you need

// Minimal import - ~3 KB
import { createLogger } from '@sylphx/cat'

// Full import - ~9 KB
import {
  createLogger,
  jsonFormatter,
  prettyFormatter,
  consoleTransport,
  fileTransport,
  otlpTransport,
  tracingPlugin,
  redactionPlugin,
  tailSamplingPlugin
} from '@sylphx/cat'

🌍 Universal Runtime Support

Works everywhere JavaScript runs:

Runtimes:

• Node.js 18+
• Bun 1.0+
• Deno 1.30+
• Browsers (Chrome, Firefox, Safari, Edge)
• Cloudflare Workers
• Vercel Edge Runtime
• AWS Lambda@Edge

Frameworks:

• Express
• Fastify
• Next.js
• Remix
• Astro
• SvelteKit
• Hono

// Works identically in all environments
import { createLogger } from '@sylphx/cat'

const logger = createLogger()
logger.info('Universal logging!')

🔒 Security-First Design

OWASP 2024 compliant with built-in security features:

import { redactionPlugin } from '@sylphx/cat'

const logger = createLogger({
  plugins: [
    redactionPlugin({
      // Auto-redact sensitive fields
      fields: ['password', 'token', '*.secret', '**.apiKey'],

      // PII detection
      redactPII: true,

      // Log injection prevention
      preventLogInjection: true
    })
  ]
})

logger.info('User login', {
  username: 'john',
  password: 'secret123', // → [REDACTED]
  creditCard: '4532-1234-5678-9010' // → [REDACTED]
})

Security features:

• Automatic PII redaction (credit cards, SSNs, emails, phones)
• Log injection prevention (OWASP)
• Sensitive header redaction
• Custom redaction patterns
• Field-level exclusions

📊 Enterprise-Grade Observability

Full OpenTelemetry integration with W3C Trace Context:

import { tracingPlugin, otlpTransport } from '@sylphx/cat'

const logger = createLogger({
  transports: [
    otlpTransport({
      endpoint: 'https://otlp-gateway.grafana.net/otlp/v1/logs',
      headers: { Authorization: 'Bearer <token>' },
      resourceAttributes: {
        'service.name': 'my-api',
        'service.version': '1.0.0'
      }
    })
  ],
  plugins: [tracingPlugin()]
})

// Auto-generates traceId and spanId
logger.info('Request processed')
// Output: { traceId: '0af7651916cd43dd8448eb211c80319c',
//           spanId: 'b7ad6b7169203331', ... }

Compatible with:

• Grafana Loki
• Datadog
• New Relic
• AWS CloudWatch
• Honeycomb
• Jaeger
• Zipkin
• Any OTLP-compatible backend

💰 Cost Optimization

40-90% reduction in log volume with tail-based sampling:

import { tailSamplingPlugin } from '@sylphx/cat'

const logger = createLogger({
  plugins: [
    tailSamplingPlugin({
      adaptive: true,
      monthlyBudget: 10 * 1024 * 1024 * 1024, // 10 GB/month

      // Keep 100% of errors, 1% of success logs
      // Maintains 100% error coverage while reducing costs
    })
  ]
})

Smart sampling:

• 100% error coverage (never miss issues)
• Keep slow requests (>1s)
• Sample success logs at low rate
• Budget-aware adaptive sampling
• Configurable rules per use case

🎯 Type-Safe Development

Full TypeScript support with comprehensive types:

import type { Logger, LogEntry, Plugin, Transport, Formatter } from '@sylphx/cat'

// Type-safe plugins
const myPlugin: Plugin = {
  name: 'my-plugin',
  onLog(entry: LogEntry): LogEntry {
    return { ...entry, data: { ...entry.data, timestamp: Date.now() } }
  }
}

// Type-safe custom transport
const myTransport: Transport = {
  async log(entry: LogEntry, formatted: string): Promise<void> {
    await fetch('/logs', { method: 'POST', body: formatted })
  }
}

// Autocomplete and type checking
logger.info('Message', { userId: 123 }) // ✓ Valid

📦 Tree-Shakeable

Import only what you need for optimal bundle size:

// Option 1: Minimal (3-4 KB)
import { createLogger } from '@sylphx/cat'

// Option 2: Cherry-pick features (5-6 KB)
import { createLogger, jsonFormatter, consoleTransport } from '@sylphx/cat'

// Option 3: Full featured (8-9 KB)
import * as cat from '@sylphx/cat'

Modern bundlers (Webpack, Rollup, esbuild) automatically remove unused code.

When to Choose @sylphx/cat

Perfect for:

✅ High-performance applications

• Need 20M+ ops/sec logging throughput
• Minimal CPU and memory overhead
• Zero GC pressure

✅ Universal/multi-runtime apps

• Deploy to Node.js, Deno, Bun, browsers, edge
• Single codebase across platforms
• Isomorphic logging

✅ Production observability

• OpenTelemetry integration required
• Distributed tracing across microservices
• Cost-optimized logging at scale

✅ Security-conscious applications

• PII and sensitive data redaction
• OWASP compliance requirements
• Financial, healthcare, or regulated industries

✅ Cost-sensitive deployments

• Pay-per-GB log ingestion (Datadog, New Relic)
• High log volume (millions per day)
• Need tail-based sampling

✅ Modern TypeScript projects

• Full type safety
• Excellent autocomplete
• Framework-agnostic

Consider alternatives if:

❌ You need Node.js-specific features

• Pino's worker threads
• Winston's transport ecosystem

❌ You have extremely complex custom transports

• Winston has 100+ community transports
• Cat is newer with growing ecosystem

❌ You need legacy Node.js support

• Cat requires Node.js 18+
• Pino/Winston support older versions

Migration from Other Loggers

See our Migration Guide for detailed instructions on migrating from:

• Pino
• Winston
• Bunyan
• console.log

Next Steps

• Getting Started - Quick start guide
• Best Practices - Production patterns
• Examples - Real-world examples
• API Reference - Complete API documentation