Deterministic JSON Serialization: json-stable-stringify vs json-stable-stringify-without-jsonify

Both json-stable-stringify and json-stable-stringify-without-jsonify solve a common but subtle problem in JavaScript applications: producing consistent, predictable JSON output regardless of property insertion order. This matters when you need to compare objects, generate cache keys, or create digital signatures — situations where { a: 1, b: 2 } and { b: 2, a: 1 } must serialize identically.

However, these packages differ significantly in implementation strategy, dependencies, and compatibility. Let’s break down what each offers and where they diverge.

🔍 Core Purpose: Why Stable Stringification Matters

Native JSON.stringify() does not guarantee consistent key ordering across environments or even within the same runtime if object properties were added in different orders:

// Unreliable with native JSON.stringify
const obj1 = { a: 1, b: 2 };
const obj2 = { b: 2, a: 1 };

console.log(JSON.stringify(obj1) === JSON.stringify(obj2)); // false in some engines

Stable stringifiers sort object keys alphabetically before serialization, ensuring deterministic output:

// Both packages produce this consistently:
'{"a":1,"b":2}'

This is essential for:

• Generating reliable cache keys
• Creating content hashes or digital signatures
• Comparing configuration objects
• Debugging state diffs in Redux-like systems

⚙️ Implementation Strategy: Dependency on jsonify

The key difference lies in how each package handles circular references and complex data types.

json-stable-stringify uses the jsonify package internally to safely handle edge cases like:

• Circular references
• Undefined values
• Functions
• Non-enumerable properties

// json-stable-stringify
import stableStringify from 'json-stable-stringify';

const obj = { b: 2, a: 1 };
console.log(stableStringify(obj)); // '{"a":1,"b":2}'

// Handles circular refs gracefully
const circular = { a: 1 };
circular.self = circular;
console.log(stableStringify(circular)); // Throws or handles per options

json-stable-stringify-without-jsonify avoids the jsonify dependency entirely, using a simpler recursive approach that only supports plain JSON-compatible data (objects, arrays, strings, numbers, booleans, null). It will fail or behave unpredictably with:

• Functions
• Undefined values
• Circular structures
• Symbols

// json-stable-stringify-without-jsonify
import stableStringify from 'json-stable-stringify-without-jsonify';

const obj = { b: 2, a: 1 };
console.log(stableStringify(obj)); // '{"a":1,"b":2}'

// Will crash on circular refs
const circular = { a: 1 };
circular.self = circular;
// stableStringify(circular); // Maximum call stack size exceeded

📦 Dependency Footprint and Compatibility

json-stable-stringify pulls in jsonify as a transitive dependency. While jsonify is a small, well-maintained package, this adds an extra layer to your dependency tree. However, it ensures robust handling of non-standard inputs.

json-stable-stringify-without-jsonify has zero dependencies, making it ideal for:

• Minimal bundle size requirements
• Environments where dependency constraints are strict
• Cases where you control input data and know it’s strictly JSON-safe

🛠️ API and Options Support

Both packages support identical core APIs and options:

// Common options supported by both
stableStringify(obj, {
  space: 2,           // indentation
  cmp: (a, b) => a.key < b.key ? -1 : 1, // custom sort
  replacer: (key, val) => /* transform values */
});

However, only json-stable-stringify properly respects the replacer function for non-JSON-safe values because of its jsonify foundation. The -without-jsonify variant may ignore or mishandle replacer logic when encountering functions or undefined.

🧪 Real-World Usage Scenarios

Scenario 1: Generating Cache Keys from Config Objects

You’re building a build tool that caches transformation results based on config hashes.

• ✅ Best choice: json-stable-stringify-without-jsonify
• Why? Your configs are guaranteed to be plain objects with no functions or circular refs. Zero deps = smaller install footprint.

import stringify from 'json-stable-stringify-without-jsonify';
import crypto from 'crypto';

function getConfigHash(config) {
  return crypto.createHash('sha256')
    .update(stringify(config))
    .digest('hex');
}

Scenario 2: Serializing Redux State for Time-Travel Debugging

Your app stores complex state that might include non-serializable values during development.

• ✅ Best choice: json-stable-stringify
• Why? You need graceful handling of accidental non-JSON values (e.g., React components in state) without crashing.

import stableStringify from 'json-stable-stringify';

// Safely serialize even if state contains unexpected values
const snapshot = stableStringify(reduxState, {
  replacer: (key, value) => {
    if (typeof value === 'function') return '[Function]';
    return value;
  }
});

Scenario 3: Creating Digital Signatures for API Payloads

You’re signing payloads that must be strictly JSON-compliant per spec.

• ✅ Either works, but prefer json-stable-stringify-without-jsonify
• Why? Input validation should happen upstream; you want minimal, auditable code for the signing step.

⚠️ Critical Limitation of json-stable-stringify-without-jsonify

The -without-jsonify variant will crash on circular references due to infinite recursion. If there’s any chance your data might contain cycles (common in tree structures, DOM-like objects, or ORM models), do not use it.

// Dangerous with json-stable-stringify-without-jsonify
const node = { id: 1 };
node.children = [{ parent: node }]; // Circular!

// This will throw: RangeError: Maximum call stack size exceeded
stringify(node);

In contrast, json-stable-stringify detects cycles and throws a clear error (or handles them if you provide a custom replacer).

📌 Summary Table

💡 Final Recommendation

• Choose json-stable-stringify if you need robustness against malformed or complex inputs, especially in libraries or tools where you don’t control the data shape.

• Choose json-stable-stringify-without-jsonify only if you have full control over input data (guaranteed JSON-safe, no cycles) and prioritize minimal dependencies.

Remember: deterministic output is useless if your app crashes during serialization. When in doubt, go with the more resilient option.