Introduction

Pail is a powerful, flexible logging library for Node.js, Edge, and Browser environments. It gives you structured logging with pretty or JSON output, scoped loggers, built-in timers, and a pluggable processor/reporter architecture — all with full TypeScript support.

Features at a Glance

• Structured and pretty output — JSON, formatted console, simple text, and rotating file reporters
• Pluggable architecture — Custom processors and reporters to fit any workflow
• Scoped loggers and timers — Organize logs by context with built-in performance timing
• Interactive terminal UI — Progress bars, spinners, and interactive managers
• Production-ready — Log sampling, throttling, sensitive data redaction, and environment detection
• Wide events and framework middleware — Request-scoped logging for Express, Fastify, Hono, Elysia, SvelteKit, and Next.js
• Cross-platform — Works in Node.js, Bun, Edge runtimes, and browsers (ESM-only, Node.js ≥ 20.19)

Quick Start

npm i @visulima/pail

import { pail } from "@visulima/pail";

pail.success("Operation successful");
pail.debug("Hello", "from", "L59");
pail.pending("Write release notes for %s", "1.2.0");
pail.critical(new Error("Unable to acquire lock"));

Core Concepts

Pail is built around three pillars: log levels following RFC 5424 (extended with trace), reporters that write to different destinations (console, files, JSON), and processors that enrich or transform log metadata before it reaches reporters.

What's Next?