cheshire

Cheshire

Cheshire is a fast JSON encoding/decoding library for Clojure built on Jackson. It supports JSON, SMILE, and CBOR formats, lazy decoding, custom encoders via the JSONable protocol, and configurable Jackson factories.

The primary namespace is cheshire.core. Require it as:

(ns my.ns
  (:require [cheshire.core :as json]))

Current version: [cheshire "6.2.0"] (Jackson 2.21.1).

Quick Decision: What do you need?

Task	Go to
Encode Clojure data to JSON string, stream, SMILE, or CBOR; pretty-printing; date formats; key-fn; escape options	encoding.md
Decode JSON string, stream, or SMILE to Clojure data; keyword keys; lazy parsing; BigDecimal; array-coerce-fn	decoding.md
Add or remove custom encoders for arbitrary Java/Clojure types; JSONable protocol; encode-* helpers	custom-encoders.md
Configure Jackson factories; non-numeric numbers; comments; max sizes; SMILE/CBOR factories; dynamic binding	factory.md
Something is encoding/decoding incorrectly, throwing, or producing unexpected output	anti-patterns.md

Core Mental Model

• Encoding converts Clojure data → JSON bytes/string. Entry point: generate-string (alias: encode).
• Decoding converts JSON bytes/string → Clojure data. Entry point: parse-string (alias: decode).
• All opt-map options (:date-format, :pretty, :key-fn, :escape-non-ascii) apply at call time, not globally.
• To change Jackson behavior globally (e.g. allow NaN, raise size limits), build a custom factory and bind it via factory/*json-factory*.
• Custom type encoding is registered globally via add-encoder and removed with remove-encoder.