# ohler55/oj

Optimized JSON

Repository: https://github.com/ohler55/oj
Canonical: https://ross.abutalabs.com/products/oj
Homepage: http://www.ohler.com/oj
Language: C
License: MIT
License Family: permissive
Topics: json-parser, json, ruby, c, oj-gem, ruby-json-parser, marshaller, rails
Last push: 2026-08-13T16:41:39+00:00

## Health v2 (maintenance only)
Score: 93/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 97, release rhythm 85, longevity 100
- inputs: {"age_days": 5311, "days_push": 20, "days_rel": 23, "gap_med": 36, "n_releases_24m": 12}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3225, forks 265 (observed 2026-08-28T04:07:49.948893+00:00)

## What it is
Oj (Optimized JSON) is a fast JSON parser and object marshaller implemented as a C extension for Ruby. It serves as a drop-in replacement for the standard json gem and Rails/ActiveSupport serialization, with multiple compatibility modes.

## Use cases
- parse json fast in ruby
- serialize ruby objects to json
- drop-in replacement for ruby json gem
- speed up rails json serialization
- marshal ruby objects to json strings
- benchmark json parsing in ruby

## When to choose
- you need faster JSON encoding/decoding than the built-in json gem
- you want json gem or Rails/ActiveSystem compatibility without changing code
- you need object marshalling to JSON in Ruby

## When to avoid
- you are not working in Ruby
- you need a pure-Ruby dependency without native C extensions

## Facets
- artifact type: library
- maturity: stable
- function: serialization, parser, json
- domain: developer-tools, backend, web-development, apis
- platform: ruby, jvm
- tags: json-parser, ruby-gem, c-extension, rails, marshaller, performance

## Member repositories
- ohler55/oj (main) score 93

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:49.948893+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 2026-08-29T18:44:17.382561+00:00, confidence not recorded.
  - readme: https://github.com/ohler55/oj (fetched 2026-08-28T04:07:49.948893+00:00, sha b265104b78ab)
  - homepage: http://www.ohler.com/oj (fetched 2026-08-29T09:38:03.244895+00:00, sha defa5da2bc15)
  - site_page: http://www.ohler.com/oj/doc/index.html (fetched 2026-08-29T09:38:03.254473+00:00, sha 8908e00aa01d)
- Data as of 2026-08-30T08:39:29.467469+00:00.