jsonrepair-rs 0.1.0

Repair broken JSON — fix quotes, commas, comments, trailing content, and 30+ other issues
Documentation

jsonrepair-rs

CI Crates.io License: MIT

Repair broken JSON in Rust. Fix quotes, commas, comments, trailing content, and 30+ other issues commonly found in LLM outputs.

Rust port of josdejong/jsonrepair.

Features

Category Examples
Quote repair Single quotes → double, curly quotes, backticks, unquoted keys
Comma repair Missing, trailing, and leading commas
Comments //, /* */, # — stripped from output
Python keywords True → true, False → false, None → null
JS keywords undefined → null, NaN → null, Infinity → null
Markdown fences ```json ... ``` — extracted and repaired
Truncated JSON Auto-closes unclosed brackets, braces, and strings
Number repair Leading zeros, trailing dots (2. → 2.0), truncated exponents
String repair Concatenation ("a" + "b"), invalid escapes, unescaped control chars
JSONP callback({...}) → {...}
MongoDB ObjectId("...") → "...", NumberLong("...") → "..."
NDJSON Newline-delimited JSON → JSON array
Ellipsis [1, 2, ...] → [1, 2]
Misc BOM stripping, special whitespace, trailing semicolons

Usage

Add to your Cargo.toml:

[dependencies]
jsonrepair-rs = "0.1"

use jsonrepair_rs::jsonrepair;

// Fix single quotes (whitespace preserved)
let result = jsonrepair("{'name': 'John'}").unwrap();
assert_eq!(result, r#"{"name": "John"}"#);

// Fix trailing commas
let result = jsonrepair(r#"{"a": 1, "b": 2,}"#).unwrap();
assert_eq!(result, r#"{"a": 1, "b": 2}"#);

// Strip markdown fences
let result = jsonrepair("```json\n{\"a\": 1}\n```").unwrap();
assert_eq!(result, "\n{\"a\": 1}\n");

// Convert Python keywords
let result = jsonrepair("{\"flag\": True, \"value\": None}").unwrap();
assert_eq!(result, r#"{"flag": true, "value": null}"#);

// Handle LLM output with comments
let result = jsonrepair(r#"{
    // user info
    name: "Alice",
    age: 30,
}"#).unwrap();
assert_eq!(result, "{\n    \n    \"name\": \"Alice\",\n    \"age\": 30\n}");

Error handling

use jsonrepair_rs::{jsonrepair, JsonRepairError};

match jsonrepair("not repairable at all") {
    Ok(json) => println!("Repaired: {json}"),
    Err(e) => eprintln!("Error at position {}: {}", e.position, e.message),
}

Acknowledgments

This is a Rust port of jsonrepair by Jos de Jong.