LoggerJS

Browser and server

The same logger model runs in browsers, Node.js, workers, and edge runtimes.

Automatic collection

Opt-in integrations capture console calls, errors, network failures, routes, process events, HTTP frameworks, queues, and databases.

Reliable delivery

Transports own codecs and can use batching, retry, backoff, offline replay, crash-path flushing, and beacon delivery.

Composable processing

Middleware and processors enrich, redact, sample, dedupe, fingerprint, route, and buffer logs before delivery.

Measured hot path

Benchmarks and CI gates cover disabled levels, lean NDJSON, prepared encoders, batching, browser delivery, and size budgets.

Library-safe defaults

Library loggers stay silent until the host app configures LoggerJS, so dependencies can log without forcing output.

The LoggerJS Pipeline

CollectManual logs plus browser and Node integrations.ShapeMiddleware keeps raw records cheap and composable.ProcessProcessors project events only when richer behavior is needed.DeliverTransports choose codecs, batching, retries, and destinations.

import { createLogger, stdoutTransport } from "@loggerjs/node";
import { redactProcessor } from "@loggerjs/processors";

const logger = createLogger({
  category: ["api"],
  level: "info",
  processors: [redactProcessor({ keys: ["password", /token/i] })],
  transports: [stdoutTransport()],
});

logger.info("order created", { orderId: "ord_123" });
await logger.flush();

Where To Start

New project

Start with the Node or browser quick start, then add processors and transports for your runtime.

Production rollout

Use the production recipes and operations guide for privacy, offline queues, crash paths, and vendor delivery.

API lookup

Use the generated package and API reference pages for exports, subpaths, and public declaration reports.

Documentation Map

Getting Started covers installation, first loggers, levels, lazy messages, context, and typed events.

Concepts explains records, events, middleware, processors, transports, codecs, integrations, and routing.

Transports, Integrations, Processors, and Codecs are the main implementation references.

Production Recipes, Operations, and Performance cover rollout choices.

Benchmarks, Benchmark Matrix, and Comparison keep performance and positioning grounded in checked-in evidence.

Packages, API Reports, and Examples are generated from the current repository.

AI Skill, llms.txt, and llms-full.txt help coding agents use LoggerJS directly.

LoggerJSA faster, more powerful isomorphic logger