---
url: /logly.zig/guide/introduction.md
description: >-
  Logly.zig is a high-performance structured logging library for Zig with
  zero-copy architecture, async I/O, JSON output, file rotation, and enterprise
  features like redaction, metrics, and distributed tracing.
---

# What is Logly.zig?

Logly.zig is a high-performance, structured logging library for Zig, designed to deliver a comprehensive feature set while maximizing native Zig performance and safety guarantees.

## Key Features

### 🚀 Performance

* **Zero-Copy Architecture**: Minimized allocations for maximum throughput.
* **Asynchronous I/O**: Non-blocking write operations to keep your application responsive.
* **Thread-Safety**: Fully optimized for concurrent execution environments.
* **Efficient Buffering**: Configurable buffer strategies to balance latency and throughput.

### 🛠️ Flexibility

* **Comprehensive Log Levels**: 10 distinct levels (TRACE, DEBUG, INFO, NOTICE, SUCCESS, WARNING, ERROR, FAIL, CRITICAL, FATAL) for granular control.
* **Multi-Sink Support**: Simultaneously output to console, files, and custom destinations.
* **Custom Formatting**: Flexible template strings and full printf-style formatting support.
* **Rich Context**: Structured logging with JSON support and context binding.
* **Network Logging**: Send logs via TCP or UDP to remote servers or aggregators.
* **Custom Themes**: Define custom color themes for log levels.
* **Advanced Redaction**: Custom patterns and callbacks for sensitive data.
* **Persistent Context**: Scoped loggers with persistent fields.
* **Whole-Line Coloring**: ANSI colors wrap the entire log line (timestamp, level, message) for better visual scanning.
* **Custom Levels**: Define your own log levels with custom names, priorities, and colors.
* **Cross-Platform Colors**: Works on Linux, macOS, Windows 10+, and popular terminals.

### 🛡️ Reliability

* **Concurrency Safe**: Robust locking mechanisms ensure data integrity across threads.
* **Resilient Error Handling**: Comprehensive error types and recovery strategies.
* **Automated Rotation**: Sophisticated time-based and size-based file rotation.
* **Retention Management**: Automatic cleanup policies to manage disk usage.

## Design Philosophy

Logly.Zig is built upon the following core principles:

1. **Developer Experience**: An intuitive, ergonomic API that reduces cognitive load.
2. **Uncompromised Performance**: Optimized for high-throughput, low-latency applications.
3. **Type Safety**: Leveraging Zig's powerful compile-time checks to prevent runtime errors.
4. **Zero-Cost Abstractions**: Features that incur no runtime overhead when unused.
5. **Modularity**: A composable architecture allowing you to include only what you need.

## Enterprise Features

Logly.zig v0.0.6+ includes enterprise-grade features:

### 🔍 Filtering

Rule-based log filtering by level, message patterns, or modules.

### 📊 Sampling

Probability-based sampling, rate limiting, and every-Nth message sampling for high-volume scenarios.

### 🔒 Redaction

Automatic masking of sensitive data (passwords, API keys, PII) in log messages.

### 📈 Metrics

Built-in metrics collection for logging performance monitoring.

### 🔗 Distributed Tracing

OpenTelemetry-compatible trace context propagation with automatic span ID generation.

### 🎨 Cross-Platform Colors

Enhanced ANSI color support for Windows, Linux, macOS, and bare metal/freestanding targets.

### 📝 Method Aliases

Short aliases for common methods: `warn`/`crit` for levels, `add`/`remove`/`clear`/`count` for sink management.

## When to Use Logly.Zig

Logly.Zig is perfect for:

* **Production applications** requiring robust logging
* **High-performance systems** with strict latency requirements
* **Cross-platform projects** targeting multiple operating systems
* **Projects** that need structured logging for analysis
* **Teams** looking for a structured logging solution
* **Microservices** requiring distributed tracing support
* **Compliance-sensitive** applications needing data redaction
* **Embedded/bare metal** systems needing efficient logging

## Next Steps

* [Getting Started](/guide/getting-started) - Install and set up Logly.Zig
* [Quick Start](/guide/quick-start) - Your first logging program
* [Configuration](/guide/configuration) - Configure your logger