zap
Zap is a fast, structured logging library for Go maintained by Uber. It offers both typed and untyped logging APIs, optimized for low allocation and high throughput in performance-critical applications.
Key facts
Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.
| Field | Value |
|---|---|
| Repository | uber-go/zap |
| Owner | uber-go |
| Primary language | Go |
| License | MIT — OSI-approved |
| Stars | 24.6k |
| Forks | 1.5k |
| Open issues | 187 |
| Latest release | v1.28.0 (2026-04-28) |
| Last updated | 2026-04-28 |
| Source | https://github.com/uber-go/zap |
What zap is
Zap provides a reflection-free, zero-allocation JSON encoder with two APIs: Logger (strongly typed, minimal allocations) and SugaredLogger (loosely typed, printf-style). Benchmarks show competitive performance with 656 ns/op for logging 10 fields and zero allocations for contextual logging on pre-configured loggers.
Get the zap source
Clone the repository and explore it locally.
git clone https://github.com/uber-go/zap.gitcd zap# follow the project's README for install & configurationNeed it deployed, integrated, or customized instead? DEV.co ships production installs.
Best use cases
Implementation considerations
- Defer logger.Sync() after initialization to ensure buffered logs flush on shutdown; omitting this risks log loss in short-lived processes.
- Choose Logger for hot paths (typed fields, zero allocations) and SugaredLogger for non-critical paths (printf support, easier API); avoid mixing indiscriminately.
- Configure appropriate output encoders (JSON vs console) and levels (Info, Warn, Error) at startup; runtime reconfiguration is not natively supported.
- Structured field names and types should be standardized across the codebase to enable downstream log aggregation and querying.
- Pre-build loggers with context fields once during initialization rather than per-request to maximize allocation efficiency.
When to avoid it — and what to weigh
- Printf-style logging is a hard requirement — While SugaredLogger supports printf formatting, the typed Logger (faster path) does not. If your codebase standardizes on format strings, consider hybrid approaches or alternatives.
- Loose type safety is acceptable across the codebase — Zap's typed Logger enforces field types at compile time. Projects embracing dynamic typing may find the discipline overhead onerous without performance gains.
- Go versions older than the last two minor releases must be supported — Zap only supports the two most recent Go minor versions, making it unsuitable for projects with legacy Go version constraints.
- Simple, zero-configuration logging is preferred — Zap requires conscious choice between Logger and SugaredLogger and explicit field construction, whereas standard library logging offers immediate minimal setup.
License & commercial use
Zap is released under the MIT License, a permissive OSI-approved license.
MIT License permits commercial use, modification, and distribution. No trademark or patent restrictions are stated. Verify internal compliance policies regarding attribution and notice file inclusion, though MIT typically imposes minimal commercial restrictions.
DEV.co evaluation signals
Editorial assessment — not user reviews. Directional, with an explicit confidence level.
| Signal | Assessment |
|---|---|
| Maintenance | Active |
| Documentation | Strong |
| License clarity | Clear |
| Deployment complexity | Low |
| DEV.co fit | Strong |
| Assessment confidence | High |
Zap itself has no known exploits in the provided data. As a logging library, it handles untrusted user input passed as field values; developers must sanitize sensitive data (passwords, tokens, PII) before logging. No SIEM/audit trail features; implement separately if required. Keep Zap updated to patch any future vulnerabilities in the core library or dependencies.
Alternatives to consider
zerolog
Similar zero-allocation design and JSON output; benchmarks show zerolog 42% faster on simple messages. Smaller ecosystem; choose if peak performance is the sole priority.
slog (stdlib)
Go 1.21+ standard library logging with structured support. Trade-off: slower (278% per README benchmarks) but no external dependency and full Go team support. Suitable for general-purpose apps.
logrus
Widespread adoption and familiarity; hooks, formatters, and middleware. Much slower (1677% per benchmarks) and higher allocations; avoid for latency-critical workloads.
Build on zap with DEV.co software developers
Our DevOps and application development teams can help you implement structured logging, optimize log aggregation, and design observability pipelines for your microservices. Contact us to discuss your logging architecture.
Talk to DEV.coRelated on DEV.co
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zap FAQ
Why does Zap support only the two most recent Go minor versions?
Should I always use Logger instead of SugaredLogger for better performance?
Can Zap rotate or archive log files automatically?
How do I correlate logs across microservices?
Software developers & web developers for hire
Adopting zap is usually one piece of a larger software development effort. As a software development agency, DEV.co provides software development services and web development expertise — pairing senior software developers and web developers with your team to design, build, and operate open-source observability software in production.
Ready to integrate Zap into your Go infrastructure?
Our DevOps and application development teams can help you implement structured logging, optimize log aggregation, and design observability pipelines for your microservices. Contact us to discuss your logging architecture.