compare-json (Go)

compare-json-go is the Go port of compare-json — structured JSON comparison with the same semantics as the engine that powers this website. It detects additions, deletions, type changes, and value changes between two JSON values, with control over how keys, values, and arrays are matched. Ships as both a library and a CLI, with zero external dependencies.

Language: Go — distributed via pkg.go.dev. Source code on GitHub.

Installation

go get github.com/unitstack/compare-json-go

Quick Start

Library

package main

import (
	"encoding/json"
	"fmt"

	comparejson "github.com/unitstack/compare-json-go"
)

func main() {
	var base, contrast interface{}
	json.Unmarshal([]byte(`{"name":"Alice","age":30}`), &base)
	json.Unmarshal([]byte(`{"name":"Bob","age":"30","email":"[email protected]"}`), &contrast)

	diffs := comparejson.CompareJSON(base, contrast, &comparejson.CompareOptions{
		ArrayCompareMethod: comparejson.ArrayCompareByIndex, // or ArrayCompareLCS, ArrayCompareUnordered
	})
	for _, d := range diffs {
		fmt.Println(d.PathString, d.PathBelongsTo, d.DiffType)
	}
	// name   both     valueChanged
	// age    both     typeChanged
	// email  contrast added
}

CLI

# Compare JSON files
compare-json base.json contrast.json

# Array strategies and case-insensitive matching
compare-json -a lcs -k -v base.json contrast.json

# Machine-readable JSON output
compare-json --json-export base.json contrast.json

# Write the report to a file
compare-json -o diff.txt base.json contrast.json

Note: with the stdlib flag package, flags must come before the positional arguments.

Options

Flag	Description
`-a, --array-compare-method`	Array comparison strategy: `byIndex` (default), `lcs`, `unordered`
`-k, --key-case-insensitive`	Compare object keys case-insensitively
`-v, --value-case-insensitive`	Compare string values case-insensitively
`--numeric-string-equals-number`	Treat numeric strings as equal to numbers
`-j, --json-export`	Output the differences as JSON
`-o, --output <file>`	Write output to a file instead of stdout

See Comparison Options and Array Comparison Methods for what each setting does.

License

MIT