# What is Keelog? \[Learn why Keelog exists and when to use it]

**Keelog** is a zero‑config console logger for Node.js and Bun that automatically captures caller context (file, function, line) without any manual setup.

It provides a fluent API, beautiful tree output for objects (Unicode with syntax colours), and production‑ready JSON when `NODE_ENV=production`.

## Why Keelog?

* **Automatic context** – file, function, and line number are captured for every leveled log.
* **Fluent API** – chain `.depth(n)` and `.options({ label, ctx })` on any log call.
* **Structured by default** – objects are pretty‑printed as Unicode trees with syntax colours.
* **Dual‑mode output** – beautiful TTY in development, formatted JSON in production.
* **Lightweight dependencies** – `picocolors` and `prettyoutput` (both tiny and fast).
* **Smart level filtering** via `LOG_LEVEL` environment variable.
* **Simple default log** – `log("message")` gives a clean, prefix‑free output.