OjG: Optimized JSON for Go


Optimized JSON for Go is a high performance parser with a variety of additional JSON tools. OjG is optimized to processing huge data sets where data does not necessarily conform to a fixed structure.


  • Fast JSON parser. Check out the cmd/benchmarks app in this repo.
  • Full JSONPath implemenation that operates on simple types as well as structs.
  • Generic types. Not the proposed golang generics but type safe JSON elements.
  • Fast JSON validator (7 times faster with io.Reader).
  • Fast JSON writer with a sort option (4 times faster).
  • JSON builder from JSON sources using a simple assembly plan.
  • Simple data builders using a push and pop approach.
  • Object encoding and decoding using an approach similar to that used with Oj for Ruby.
  • Simple Encoding Notation, a lazy way to write JSON omitting commas and quotes.


A basic Parse:

    obj, err := oj.ParseString(`{

Using JSONPath expressions:

    x, err := jp.ParseString("a[?(@.x > 1)].y")
    ys := x.Get(obj)
    // returns [4]

The oj command (cmd/oj) uses JSON path for filtering and extracting JSON elements. It also includes sorting, reformatting, and colorizing options.

$ oj -m "(@.name == 'Pete')" myfile.json

More complete examples are available in the go docs for most functions. The example for Unmarshalling interfaces demonstrates a feature that allows interfaces to be marshalled and unmarshalled.


go get github.com/ohler55/ojg
go get github.com/ohler55/ojg/cmd/oj

or just import in your .go files.

import (

To build and install the oj application:

go install ./...

The oj application can be installed with brew.

brew tap ohler55/tap
brew install oj


Higher numbers (longer bars) are better.

Parse string/[]byte
       json.Unmarshal           55916 ns/op    17776 B/op    334 allocs/op
         oj.Parse               39570 ns/op    18488 B/op    429 allocs/op
   oj-reuse.Parse               17881 ns/op     5691 B/op    364 allocs/op

   oj-reuse.Parse        █████████████████████▉ 3.13
         oj.Parse        █████████▉ 1.41
       json.Unmarshal    ▓▓▓▓▓▓▓ 1.00

Parse io.Reader
       json.Decode              63029 ns/op    32449 B/op    344 allocs/op
         oj.ParseReader         34289 ns/op    22583 B/op    430 allocs/op
   oj-reuse.ParseReader         25094 ns/op     9788 B/op    365 allocs/op
         oj.TokenizeLoad        13610 ns/op     6072 B/op    157 allocs/op

         oj.TokenizeLoad ████████████████████████████████▍ 4.63
   oj-reuse.ParseReader  █████████████████▌ 2.51
         oj.ParseReader  ████████████▊ 1.84
       json.Decode       ▓▓▓▓▓▓▓ 1.00

to JSON with indentation
       json.Marshal             78762 ns/op    26978 B/op    352 allocs/op
         oj.JSON                 7662 ns/op        0 B/op      0 allocs/op
        sen.Bytes                9053 ns/op        0 B/op      0 allocs/op

         oj.JSON         ███████████████████████████████████████████████████████████████████████▉ 10.28
        sen.Bytes        ████████████████████████████████████████████████████████████▉ 8.70
       json.Marshal      ▓▓▓▓▓▓▓ 1.00

See all benchmarks

Compare Go JSON parsers




Documentation: https://pkg.go.dev/github.com/ohler55/ojg

GitHub repo: https://github.com/ohler55/ojg

JSONPath draft specification: https://datatracker.ietf.org/doc/draft-ietf-jsonpath-base

JSONPath Comparisons: https://cburgmer.github.io/json-path-comparison

Go Report Card: https://goreportcard.com/report/github.com/ohler55/ojg

Links of Interest

Oj, a Ruby JSON parser: http://www.ohler.com/oj/doc/index.html also at https://github.com/ohler55/oj

OjC, a C JSON parser: http://www.ohler.com/ojc/doc/index.html also at https://github.com/ohler55/ojc

Fast XML parser and marshaller on GitHub: https://github.com/ohler55/ox

Agoo, a high performance Ruby web server supporting GraphQL on GitHub: https://github.com/ohler55/agoo

Agoo-C, a high performance C web server supporting GraphQL on GitHub: https://github.com/ohler55/agoo-c


  • Provide a Pull Request off the develop branch.
  • Report a bug
  • Suggest an idea

Download Details:

Author: ohler55
Source Code: https://github.com/ohler55/ojg 
License: MIT license

#go #golang #json 

OjG: Optimized JSON for Go
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