jsonrepair

A Go library that repairs malformed JSON and JSON-adjacent text into valid JSON

Features

• Missing syntax repair: Adds missing quotes, commas, colons, and closing brackets when the intent is clear.
• Quote normalization: Converts single quotes and smart quotes into valid JSON string quotes.
• Comment removal: Removes JavaScript-style line and block comments.
• Wrapper cleanup: Strips Markdown code fences, JSONP callbacks, MongoDB wrappers, and ellipsis placeholders.
• Literal conversion: Converts Python-style None, True, and False into JSON literals.
• String recovery: Repairs escaped strings, concatenated strings, and common truncated string input.
• NDJSON repair: Converts newline-delimited JSON values into one JSON array.

Installation

go get github.com/kaptinlin/jsonrepair

Requires Go 1.26.4+.

Quick Start

package main
import (
    "fmt"
    "log"
"github.com/kaptinlin/jsonrepair"
)
func main() {
    repaired, err := jsonrepair.Repair("{name: 'John'}")
    if err != nil {
        log.Fatal(err)
    }
fmt.Println(repaired)
}

Output:

{"name": "John"}

API

func Repair(text string) (string, error)

Repair returns the repaired JSON document or a structured *jsonrepair.Error when the input cannot be repaired.

repaired, err := jsonrepair.Repair(input)
if err != nil {
    var repairErr *jsonrepair.Error
    if errors.As(err, &repairErr) {
        fmt.Printf("%s at position %d\n", repairErr.Message, repairErr.Position)
    }
}

Sentinel errors support errors.Is:

• ErrUnexpectedEnd
• ErrObjectKeyExpected
• ErrColonExpected
• ErrInvalidCharacter
• ErrUnexpectedCharacter
• ErrInvalidUnicode

Development

task test    # Run tests with race detection
task lint    # Run golangci-lint and go mod tidy check
task         # Run lint and test

Contributing

Contributions are welcome. Open an issue to discuss substantial changes before submitting a pull request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgements

This library is a Go port of Jos de Jong's JavaScript jsonrepair library.