How to Unescape Double Backslashes in JSON Strings Instantly

Developers dealing with database logs, API webhooks, or cURL output frequently encounter double-escaped JSON string literals like "{\"user\": \"\\\"John\\\"\", \"id\": 101}". Passing such strings into standard JSON.parse() methods leads to immediate syntax errors like Uncaught SyntaxError: Unexpected token in JSON at position or JSON.parse error bad control character in string literal.

1. Understanding escape sequences in JSON

In standard JSON syntax, string values containing double quotes or control characters must be escaped with a backslash (\", \n, \t, \\). When an already-stringified JSON object is serialized a second time (for instance, storing a JSON payload inside a text column in PostgreSQL or logging via Datadog), backslashes are themselves escaped, producing double backslashes (\\\" and \\\\).

2. Common causes of double-escaped JSON

• Nested REST API Payload Serializations: Calling JSON.stringify() on an object that already contains a stringified property value.
• Database SQL String Exports: Exporting string columns containing JSON text without unescaping double quotes.
• Log Aggregators & Shell CLI Logs: cURL parameters or Bash echo outputs escaping quotes for terminal compatibility.

3. Programmatic fixes in popular languages

JavaScript / Node.js

In JavaScript, double-escaped strings require double parsing or string replacement:

// Double parse pattern for double-encoded JSON
const rawString = "\"{\\\"user\\\": \\\"John\\\", \\\"role\\\": \\\"admin\\\"}\"";
const firstPass = JSON.parse(rawString); // Returns string payload
const validObject = JSON.parse(firstPass); // Returns JavaScript object
console.log(validObject.user); // "John"

Python

In Python, use the json.loads() function twice or codecs.decode():

import json

escaped_str = '"{\\"user\\": \\"John\\", \\"role\\": \\"admin\\"}"'
# Parse outer string then inner object
clean_str = json.loads(escaped_str)
data = json.loads(clean_str)
print(data['user']) # 'John'

Go (Golang)

In Go, unquote the string before unmarshaling into a struct:

package main

import (
    "encoding/json"
    "fmt"
    "strconv"
)

func main() {
    escaped := `"{\"user\": \"John\", \"role\": \"admin\"}"`
    unquoted, _ := strconv.Unquote(escaped)
    
    var result map[string]interface{}
    json.Unmarshal([]byte(unquoted), &result)
    fmt.Println(result["user"]) // John
}

4. Instant in-browser unescaping

Instead of writing fragile regex replace expressions or manual terminal commands, paste your double-encoded payload into OnlineViewer Dev's JSON Unescape Tool. It detects escaped quote patterns (\" → "), unescapes double backslashes, and instantly produces cleanly formatted JSON trees.

5. Frequently asked questions