Logging

Structured logs for Node, Bun, Workers, and the browser.

Node / Bun

★ pino — fastest JSON logger; the default for new Node services. Pairs with pino-pretty (dev) and any log shipper (production).
Winston — older incumbent; transports for everything; bigger surface area than pino.
bunyan — older still; pino is its spiritual successor.
consola (UnJS) — gorgeous CLI output; used by Nuxt / Nitro. Great for tools / CLIs; less for production services.
debug — namespaced DEBUG=app:* node x.js style; tiny; useful in libraries.
signale — pretty CLI logger.
@logtape/logtape — modern structured logger; Node/Bun/Workers.

★ @logtape/logtape — works on Workers, Deno, Bun, Node.
★ Workers built-in console — stream to Workers Logs / Logpush.
pino with transport.target: 'pino/file' and an external shipper, or pino-cloudwatch family.

console — fine for most needs.
loglevel — minimal browser-friendly logger.
debug — works in the browser too (localStorage.debug = 'app:*').
Sentry ships breadcrumbs and console captures automatically; see Observability.

Always JSON in production — pretty-print in dev only.
Correlation IDs — propagate traceparent (W3C Trace Context) so logs from one request all share an ID.
Levels — trace / debug / info / warn / error / fatal. Default to info in prod.
Don't log secrets — never log full tokens, full request bodies of auth flows, full DB rows with PII.
Sample high-volume logs — pino has level per route; or sample 1% in prod.
Pair with OpenTelemetry — see Observability for traces/metrics that pair with logs.

Better Stack, Axiom, Datadog, Honeycomb, OpenObserve, Grafana Loki, Cloudflare Logpush — see Observability.
Vercel Log Drains — push Vercel logs anywhere.
pino-axiom, pino-better-stack, pino-datadog — pino transports.