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zerolog

A fast Go logging library that writes structured JSON with almost no memory allocation.

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Stars
12.5k
Forks
661
Licence
MIT
Language
Go
Last update
23 days ago
Type
Library

What it is

Zerolog is a logging library for the Go programming language. It records events as structured JSON (or optionally CBOR), where each message can carry typed key-value fields such as strings, numbers, and errors. It is built to avoid allocations and reflection, which the README says keeps it fast and light on memory.

  • Logging HTTP request details as structured fields
  • Attaching contextual data such as user IDs to each log event
  • Logging errors with optional stack traces using the pkgerrors package
  • Filtering output by level (trace through panic) or turning logging off
  • Using log sampling and hooks to control which events get written

Great for

  • Go developers who want machine-readable JSON logs
  • Backend services where logging overhead matters
  • Teams that log structured fields and send logs to log-processing tools
  • Developers who want a chained, typed logging API

Not ideal for

  • People who want readable colored console output by default: the README says pretty printing via ConsoleWriter is available but inefficient
  • Non-Go projects, since it is a Go package
  • Beginners who need a full logging framework with rotation or file management, which the README does not describe
Step-by-step guide: how to use zerologInstall, first run, examples, tips and FAQs
Logrus vs zerologzap vs zerolog

How to get it

  1. 1

    Install with a package manager

    You'll need: Go

    Install the global logger package

    go get -u github.com/rs/zerolog/log
  2. 2

    Run it

    • Install the package with go get as shown in the README
    • Create a main.go file that imports github.com/rs/zerolog/log
    • Call log.Print("hello world") or log.Info().Msg("hello world") inside main
    • Run the program and read the JSON line written to stderr
  3. 3

    Get the most out of it

    • Set zerolog.TimeFieldFormat to zerolog.TimeFormatUnix for smaller timestamps, as the README suggests
    • Call zerolog.SetGlobalLevel to hide trace and debug output in production
    • Use zerolog.ConsoleWriter during development for readable output
    • Use the pkgerrors package with zerolog.ErrorStackMarshaler to add stack traces to errors
    • Use the context.Context and net/http integrations listed in the README

Downloads

Source code (.zip)master branch · straight from GitHub

Strengths

  • Designed for low or zero allocation, per the README benchmarks section
  • Strongly typed fields and a simple chaining API
  • Supports leveled logging, sampling, hooks, and log/slog integration

Trade-offs

  • Chained calls silently do nothing unless Msg or Msgf is called, and the compiler will not warn you
  • By default it writes every level, including trace, to stderr until SetGlobalLevel is called
  • Pretty console output is available but slower, as the README notes

How it compares

ProjectStarsTypeLevelUpdatedBest for
zerolog (this)12.5kLibrarybeginner23 days agoGo developers who want machine-readable JSON logs
zap24.7kLibrarybeginner2 months agoGo developers building services that log heavily
logrus25.8kLibrarybeginner1 months agoGo developers with existing code that already uses Logrus
gjson15.6kLibrarybeginner1 months agoGo developers who need a few fields from a JSON response without writing struct definitions
go13.9kLibrarybeginner2.4 years agoGo developers who parse or produce large amounts of JSON and want to test a faster option
gf13.3kFrameworkintermediate7 days agoGo developers looking for a full-featured framework

Stats synced from GitHub. The assessment above was drafted with AI from the project's README on 2026-10-29 and may miss recent changes — check the README before relying on a command. MIT licence: free to use, modify and distribute, including commercially, as long as you keep the copyright notice.