Generating Unique Identifiers in JavaScript Applications
nanoid, randomstring, shortid, and uuid are all npm packages used to generate unique identifiers in JavaScript applications, but they differ significantly in design goals, collision resistance, output format, and suitability for modern frontend environments. uuid is the most mature and standards-compliant, producing universally unique identifiers (UUIDs) per RFC specifications. nanoid focuses on compact, URL-safe IDs with minimal size and high performance using cryptographically strong randomness. randomstring offers flexible string generation with extensive customization options but isn’t specifically designed for unique ID use cases. shortid was created to produce short, non-sequential IDs but has known limitations in uniqueness guarantees and is no longer maintained.
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Generating Unique IDs in JavaScript: nanoid vs randomstring vs shortid vs uuid
When building modern web apps, you’ll often need to generate unique identifiers — for temporary DOM elements, client-side entity keys, cache entries, or sync tokens. But not all ID generators are created equal. Let’s break down how nanoid, randomstring, shortid, and uuid actually behave in real-world frontend scenarios.
🔢 What Kind of ID Do You Really Need?
Before comparing libraries, ask: What problem am I solving?
- Globally unique across systems? → Use
uuid. - Short, fast, client-only IDs? → Use
nanoid. - Custom-formatted random text (not necessarily unique)? → Consider
randomstring. - Legacy compatibility? → Avoid
shortid; migrate away.
Each package makes different trade-offs between size, safety, standardization, and flexibility.
🧪 Collision Resistance: How Safe Is "Unique"?
uuid generates RFC-compliant identifiers. Version 4 (random-based) uses 122 bits of entropy — so the chance of collision is astronomically low, even at billions of IDs per second. This is why databases like PostgreSQL natively support UUIDs.
// uuid v4 example
import { v4 as uuidv4 } from 'uuid';
const id = uuidv4(); // '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d'
nanoid uses a larger alphabet (A-Za-z0-9_-) and defaults to 21 characters, giving ~126 bits of entropy — comparable to UUID v4 but in a shorter string. It leverages the browser’s crypto.getRandomValues() for true randomness, making it safe for client-side use.
// nanoid example
import { nanoid } from 'nanoid';
const id = nanoid(); // 'V1StGXR8_Z5jdHi6B-myT'
randomstring doesn’t guarantee uniqueness. It’s a general-purpose string generator. If you call it twice with the same settings, you might get duplicates — and there’s no built-in mechanism to prevent that.
// randomstring — not for unique IDs!
import randomstring from 'randomstring';
const str = randomstring.generate(10); // 'aB3xK9mQ2p' — could repeat
shortid uses only 7–14 characters with a small alphabet, resulting in very limited entropy. Worse, it relied on a shared internal counter that resets on app restart — causing predictable sequences and high collision risk in serverless or multi-tab environments. It is deprecated and should not be used in new code.
📏 Output Format and Size Matter
uuid: Always 36 chars (with hyphens). Hard to shorten safely.nanoid: Default 21 chars, no special characters, URL-safe.randomstring: Fully configurable — but defaults aren’t optimized for IDs.shortid: ~7–10 chars, but unsafe.
If you’re embedding IDs in URLs or class names, nanoid’s compact, clean output wins. For database keys or API payloads where standards matter, uuid’s structure is an advantage.
🌐 Browser Compatibility and Security
All four work in browsers, but security differs:
nanoidanduuidboth use cryptographically secure random sources in modern browsers (crypto.getRandomValues).randomstringfalls back toMath.random()unless you explicitly enable secure mode — which many developers forget.shortidused insecure randomness in early versions and never updated its approach.
Never trust Math.random() for anything requiring uniqueness or unpredictability — it’s deterministic and easily guessable.
⚙️ Customization vs Simplicity
Need a 12-character alphanumeric ID without vowels (to avoid accidental words)? randomstring can do that:
randomstring.generate({
length: 12,
charset: 'abcdefghjkmnpqrstuvwxyz23456789'
});
But if you just need a safe, short ID with zero config, nanoid is simpler:
nanoid(12); // 'K7cL9pXqR2mN'
uuid offers versioned generation (e.g., time-based v1 or lexicographically sortable v7), useful for databases, but adds complexity if you don’t need it.
🛑 The Shortid Situation
shortid was popular around 2016–2018 for its brevity, but its author officially deprecated it in 2019, recommending nanoid as a replacement. Known issues include:
- Collisions after ~16k IDs in a single process
- Non-cryptographic randomness
- No updates for modern JavaScript environments
If you see it in a codebase, treat it as technical debt.
✅ Practical Recommendations
| Use Case | Best Choice |
|---|---|
| Client-side React keys, temp IDs | nanoid |
| Database primary keys, API identifiers | uuid (v4 or v7) |
| Test data, passwords, mock content | randomstring |
| Any new project needing short IDs | Not shortid — use nanoid |
💡 Pro Tip: Avoid Reinventing the Wheel
Don’t roll your own ID generator using Date.now() + Math.random(). Even subtle bugs can cause hard-to-debug duplication issues in production. Stick to battle-tested libraries that understand entropy, randomness, and collision math.
In summary: Use nanoid for short client IDs, uuid for system-wide uniqueness, randomstring for non-unique random text, and never shortid in new code.
How to Choose: nanoid vs randomstring vs shortid vs uuid
- nanoid:
Choose
nanoidwhen you need very short, URL-safe identifiers with strong uniqueness guarantees and minimal bundle impact. It’s ideal for client-side ID generation in SPAs, cache keys, or temporary DOM element IDs where size and speed matter. Its use of cryptographic randomness (via Web Crypto API in browsers) ensures low collision risk even at scale, and it avoids problematic characters like hyphens or underscores by default. - randomstring:
Choose
randomstringwhen your primary need is customizable random strings — not necessarily globally unique IDs. It shines in scenarios like password generation, test fixtures, or placeholder content where you control length, character sets, and patterns. However, avoid it for distributed ID generation since it lacks built-in collision resistance strategies and isn’t optimized for uniqueness. - shortid:
Do not choose
shortidfor new projects. It is deprecated and no longer maintained, with documented issues around ID collisions under moderate load due to its limited entropy and reliance on process-specific counters. If you’re maintaining legacy code that uses it, plan a migration tonanoidoruuid. - uuid:
Choose
uuidwhen you need standards-compliant, universally unique identifiers — especially if interoperability with backend systems, databases, or external APIs is required. It supports multiple UUID versions (v1, v4, v7), with v4 being the most common for random IDs. While slightly larger thannanoidoutputs (36 characters vs ~21), its predictability, widespread adoption, and robust collision resistance make it the safe default for most production systems.
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README for nanoid
Nano ID
English | 日本語 | Русский | 简体中文 | Bahasa Indonesia | 한국어 | العربية
A tiny, secure, URL-friendly, unique string ID generator for JavaScript.
“An amazing level of senseless perfectionism, which is simply impossible not to respect.”
- Small. 118 bytes (minified and brotlied). No dependencies. Size Limit controls the size.
- Safe. It uses hardware random generator. Can be used in clusters.
- Short IDs. It uses a larger alphabet than UUID (
A-Za-z0-9_-). So ID size was reduced from 36 to 21 symbols. - Portable. Nano ID was ported to over 20 programming languages.
import { nanoid } from 'nanoid'
model.id = nanoid() //=> "V1StGXR8_Z5jdHi6B-myT"
Made at Evil Martians, product consulting for developer tools.
Docs
Read full docs here.