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How to escape and unescape a JSON string (with JavaScript and Python examples)

kb7822836-hash — Fri, 09 Oct 2026 07:17:00 +0000

Sooner or later you have to put JSON inside a string: a payload stored in a database column, a field in another JSON document, or a line in a log file. That is when quotes, backslashes and line breaks start breaking things. Here is how JSON string escaping works and how to do it correctly.

What gets escaped

Inside a JSON string, these characters must be written with a backslash:

a double quote becomes \"
a backslash becomes \\
a new line becomes \n
a tab becomes \t
a carriage return becomes \r
other control characters become \uXXXX

Writing / as \/ is allowed but not required.

Escape a string in JavaScript

Do not build the escaped text by hand. JSON.stringify does it for you:

const text = 'He said "hi"\nnext line';
const escaped = JSON.stringify(text);
// "He said \"hi\"\nnext line"   (with the surrounding quotes)

Unescape a string in JavaScript

JSON.parse reverses it. It expects the surrounding quotes to be there:

const original = JSON.parse(escaped);
// He said "hi"
// next line

JSON inside JSON (double encoding)

This is the case that confuses most people. When a JSON document is stored as a string inside another one, every quote and backslash gets escaped again:

const inner = { name: "Ali", note: 'He said "hi"' };
const outer = { payload: JSON.stringify(inner) };

JSON.stringify(outer);
// {"payload":"{\"name\":\"Ali\",\"note\":\"He said \\\"hi\\\"\"}"}

To read it back you parse twice:

const data = JSON.parse(JSON.parse(outerText).payload);

Python

import json

s = 'He said "hi"\nnext line'
escaped = json.dumps(s)
print(escaped)
# "He said \"hi\"\nnext line"

original = json.loads(escaped)
print(original == s)
# True

One difference to know: json.dumps escapes non-ASCII characters as \uXXXX by default. Pass ensure_ascii=False to keep them readable. JSON.stringify in JavaScript keeps them as they are.

Unicode escapes

JSON can write any character as \uXXXX, and JSON.parse turns it back into the real character:

JSON.parse('"caf\\u00e9"');
// "café"

In Python, json.dumps("café") gives "caf\u00e9", while json.dumps("café", ensure_ascii=False) gives "café".

Common mistakes

Using replace on quotes only. text.replace('"', '\\"') forgets backslashes and line breaks, and breaks on the first one it meets.
Parsing text that has no quotes. JSON.parse on an escaped string needs the surrounding quotes.
Mixing up escape types. JSON escaping is not URL encoding or HTML escaping. Each one has its own rules.

A quick way without code

If you just need to escape or unescape something once, I made a small free tool for it: JSON Escape and Unescape. Paste your text, press Escape or Unescape, and copy the result. It runs in your browser, so what you paste is not uploaded. The site uses Google Analytics for basic page-view counts, but it never sees your text.

If your problem is a broken JSON file rather than a string, the JSON Repair tool and the guide to common JSON parse errors may help.

How to split a large JSON file in the browser (without uploading it anywhere) published: false

kb7822836-hash — Mon, 05 Oct 2026 03:54:02 +0000

ometimes you get a huge JSON array, a few thousand records in one file, and you need it in smaller pieces. Maybe an API only accepts 500 items at a time, or your editor chokes on the file.

The easy way is to paste it into an online tool. But if the data is private, uploading it to a random server isn't a great idea. Here is how to do it entirely in the browser.

The idea

Parse the JSON, cut the array into groups of N items, and turn each group back into text.

function splitArray(arr, size) {
  const parts = [];
  for (let i = 0; i < arr.length; i += size) {
    parts.push(arr.slice(i, i + size));
  }
  return parts;
}

const data = JSON.parse(text);          // text = your file contents
const parts = splitArray(data, 500);    // 500 items per part

Splitting an object instead of an array

If the top level is an object, split its keys instead:

function splitObject(obj, size) {
  const keys = Object.keys(obj);
  const parts = [];
  for (let i = 0; i < keys.length; i += size) {
    const chunk = {};
    keys.slice(i, i + size).forEach(k => { chunk[k] = obj[k]; });
    parts.push(chunk);
  }
  return parts;
}

Saving each part as a file

Browsers can create a download from a Blob, with no server involved:

function download(name, value) {
  const blob = new Blob([JSON.stringify(value, null, 2)], { type: 'application/json' });
  const a = document.createElement('a');
  a.href = URL.createObjectURL(blob);
  a.download = name;
  a.click();
  URL.revokeObjectURL(a.href);
}

parts.forEach((p, i) => download(`part-${i + 1}.json`, p));

One catch: many browsers block several downloads fired at once, so it is safer to give each part its own download button.

A few things to watch for

Invalid JSON. JSON.parse throws on bad input, so wrap it in try/catch and show the error message to the user.
Very large files. Everything is held in memory, so a file of many megabytes can make the tab slow. For huge files, a streaming parser or a command-line tool is a better fit.
Order. Items keep their original order, so you can join the parts back together later with concat.

If you don't want to write code

I put this into a small free tool: JSON Splitter. Paste your JSON, choose how many items per part, then copy or download each part. It runs fully in your browser, and nothing you paste is uploaded.

It is part of Parsekit, a set of small JSON utilities that all run client-side: formatter, JSON to CSV and YAML, merge, diff, splitter, escape/unescape, Base64 and URL encode/decode. The site uses Google Analytics for basic page-view counts, but it never sees what you paste.

I'd love to hear which tool you'd want next, or if something breaks on an edge-case JSON file.

Built Parsekit: free JSON tools that run entirely in your browser (nothing you paste is uploaded)

kb7822836-hash — Fri, 25 Sep 2026 16:30:28 +0000

Got tired of JSON formatter sites that bury a simple tool behind popups and multi-step wizards, so I built a small collection of single-purpose ones:

JSON Formatter & Validator (with clear error location)
JSON to CSV and JSON to YAML converters
Merge JSON Files (deep merge for objects, concat for arrays)
JSON Diff, JSON Splitter, and JSON Escape/Unescape
Base64 and URL encode/decode

Everything runs client-side: what you paste is processed in your browser and never uploaded. No signup either. The site uses Google Analytics for basic page-view and button-click counts, but it never sees what you paste.

https://parsekit.net

Would love feedback, especially if something breaks on edge-case JSON, or if there's a tool you'd like next.