# json4s/json4s

JSON library

Repository: https://github.com/json4s/json4s
Canonical: https://ross.abutalabs.com/products/json4s
Language: Scala
License: Apache-2.0
License Family: permissive
Topics: json, scala, jackson
Last push: 2026-08-21T12:23:39+00:00

## Health v2 (maintenance only)
Score: 76/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 98, release rhythm 35, longevity 100
- inputs: {"age_days": 5123, "days_push": 12, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1485, forks 324 (observed 2026-08-28T04:04:51.825696+00:00)

## What it is
4s is a Scala JSON library providing a common JSON AST (JValue) with parsing, formatting, and transformation utilities. It originated as a fork of lift- and offers both a native parser and a Jackson-backed parser.

## Use cases
- parse  in scala
- serialize case classes to
- query and transform  documents with xpath-like expressions
- convert between  and xml
- diff and merge  documents
- use jackson with a lift- style ast

## When to choose
- you need a shared JSON AST across Scala libraries
- you want case class extraction from parsed JSON
- you need XML-to-JSON conversion or diff/merge features
- you prefer lift-'s API without Lift's release cycle

## When to avoid
- you want the fastest possible JSON parsing in Scala (consider circe or jackson directly)
- you need typeclass-based JSON codecs with strong compile-time guarantees
- you are not working on the JVM or with Scala

## Facets
- artifact type: library
- maturity: stable
- function: serialization, parser
- domain: developer-tools, backend, web-development
- platform: jvm
- tags: scala, jackson, -ast, lift-, case-class-extraction

## Member repositories
- json4s/json4s (main) score 76

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:51.825696+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:33:56.475548+00:00, confidence not recorded.
  - readme: https://github.com/json4s/json4s (fetched 2026-08-28T04:04:51.825696+00:00, sha a5ed1039a5e4)
- Data as of 2026-08-30T08:39:29.467469+00:00.