Quick recommendation: For the safest, standards-based choice, use
GUID / UUID v4 (fully random) or
GUID / UUID v7 (time-ordered for databases). Consider
NanoID when you need compact URL-safe identifiers for web applications and your ecosystem is primarily JavaScript/TypeScript.
NanoID - A tiny, secure, URL-friendly, unique string ID generator for JavaScript - github.com
Overview
NanoID was created by Andrey Sitnik as a lightweight alternative to UUID for JavaScript applications. Unlike standard GUIDs / UUIDs (128 bits, 36 characters), NanoID generates compact URL-safe strings (default 21 characters) with customizable size and alphabet, making it popular in web development, especially for short URLs and client-side ID generation.
When choosing an identifier for your application or database schema, you're usually deciding between standard GUIDs / UUIDs (governed by RFC 9562) and NanoID, a non-standard but popular identifier format widely used in the JavaScript ecosystem.
Comparison table
| Property | GUID / UUID v4 | GUID / UUID v7 | NanoID |
|---|
| Size | 128-bit | 128-bit | Variable (126-bit default) |
|---|
| Encoding | Hex (8-4-4-4-12) | Hex (8-4-4-4-12) | URL-safe (21 chars default) |
|---|
| Time-sortable | No | Yes (millisecond) | No |
|---|
| Standard | RFC 4122 and RFC 9562 | RFC 4122 and RFC 9562 | No RFC |
|---|
| Human-readable | Moderate
Hex with hyphens | Moderate
Hex with hyphens | Good
Compact, URL-safe |
|---|
| Database-friendly | Good
Native UUID support, but random | Excellent
Native support + sortable | Moderate
Stored as VARCHAR/TEXT |
|---|
| Collision resistant | Excellent
122 bits random | Excellent
74 bits random | Excellent
126 bits random (default) |
|---|
| Customizable | Fixed format | Fixed format | Size + alphabet |
|---|
| Best for | General-purpose IDs, privacy-friendly identifiers (no embedded data) and fully random | Database primary keys, event ordering, time-correlated IDs | URL identifiers, web tokens, JavaScript applications, short IDs |
|---|
Detailed comparison
Structure: 128 bits with 122 bits of randomness. No timestamp information.
- Pros: Universally supported, RFC standard, no time leakage, simple generation and no coordination needed
- Cons: Random insertion pattern can cause index fragmentation in some databases, larger string representation (36 chars)
- Use when: You want maximum compatibility and don't need time-ordering
Example: 550e8400-e29b-41d4-a716-446655440000
Structure: 128 bits with 48-bit Unix millisecond timestamp prefix + 74 bits randomness.
- Pros: RFC standard, time-ordered, database-friendly, widely supported and no coordination needed
- Cons: Reveals creation timestamp (millisecond precision), larger string representation (36 chars)
- Use when: You want time-ordering with RFC compliance for database primary keys
Example: 018f3f5e-1c2d-7a9b-8f10-3c4d5e6f7a8b
NanoID (Compact URL-safe Identifier)
Structure: Variable bit size (default 126 bits / 21 characters) using URL-safe alphabet (A-Za-z0-9_-).
- Pros: Very compact (21 chars vs 36 for UUID), URL-safe without encoding, customizable size and alphabet, excellent performance, tiny library size (~100 bytes) and no time leakage
- Cons: Not RFC standard, limited database native support, requires library in most languages and no time-ordering
- Use when: You need compact, URL-friendly IDs for web applications, especially in JavaScript/TypeScript ecosystems
Example: V1StGXR8_Z5jdHi6B-myT
Which one should you use?
- Choose GUID / UUID v4 if you want the safest default: widely supported, easy to store, no embedded metadata, simple generation and works across all platforms.
- Choose GUID / UUID v7 if you want a standards-based ID that is time-ordered and typically behaves better as a database primary key than random GUIDs / UUIDs.
- Choose NanoID if you need compact, URL-safe identifiers for web applications, short URLs, API tokens, or when working primarily in JavaScript/TypeScript ecosystems where size and performance matter.
Practical guidance for web applications
NanoID is particularly popular in web development and JavaScript applications where compact, URL-safe identifiers are beneficial. That's the most common reason developers compare GUID / UUID v4 and NanoID.
- Most compatible: GUID / UUID v4 (works everywhere, standardized)
- Best for databases: GUID / UUID v7 (time-ordered, native support)
- Best for web URLs: NanoID (compact, URL-safe by default, no encoding needed)
Performance considerations
- Generation speed: NanoID is extremely fast (~2-3x faster than UUID in JavaScript) due to optimized implementation and smaller output size.
- Library size: NanoID is tiny (~100 bytes gzipped) compared to UUID libraries (several KB), making it ideal for web bundles and client-side applications.
- URL length: NanoID (21 chars) is significantly shorter than UUID (36 chars), saving bytes in URLs, QR codes, and API responses.
- Storage: UUIDs benefit from native binary storage (16 bytes), while NanoID is typically stored as VARCHAR (21+ bytes), though some databases may optimize string storage.
- Collision probability: With default 21-character NanoID, collision probability is negligible (~1% after generating 150 trillion IDs), comparable to UUID security.
Interoperability and ecosystem support
GUID / UUID has the broadest support across programming languages, databases, and frameworks:
- Databases: Native GUID / UUID types in PostgreSQL, MySQL, SQL Server, Oracle, etc.
- Languages: Built-in support in Java, C#, Python, Go, Ruby, JavaScript, and many more
- APIs: JSON, REST, GraphQL commonly use GUID / UUID for resource identifiers
- ORMs: Entity Framework, Hibernate, Django ORM, and many others natively handle GUIDs / UUIDs
NanoID requires library support and is most common in JavaScript ecosystems:
- Excellent support in JavaScript/TypeScript with official package and wide adoption
- Ports available in many languages (Python, Go, Ruby, etc.) but not built into standard libraries
- Stored as VARCHAR/TEXT in databases (no native NanoID type)
- Requires custom handling in ORMs and serialization frameworks
- Popular in Node.js, React, Next.js, and modern web frameworks
Common use cases for NanoID
- Short URLs: Compact size makes NanoID ideal for URL shorteners and shareable links
- Session tokens: URL-safe, random, and compact for web session identifiers
- Client-side IDs: Generate secure IDs in the browser without server coordination
- File names: Safe for file systems and URLs without special character encoding
- API keys: Compact and random for short-lived API tokens (not for security-critical keys)
- Temp identifiers: Lightweight IDs for temporary or ephemeral resources
Other identifier formats
Beyond GUIDs / UUIDs and NanoID, there are many other identifier formats each with their own trade-offs. For a comprehensive comparison of all popular identifier formats, see our complete identifier comparison guide.
For most applications requiring broad compatibility and standards compliance, standard GUIDs / UUIDs remain the recommended choice.
Warnings and trade-offs
- Identifiers are not secrets: GUID / UUID v4 / v7 and NanoID are identifiers, not security tokens. Do not use them as passwords, encryption keys, or authentication secrets.
- Non-standard format: NanoID is not an RFC UUID. Some APIs, ORMs, and databases expect GUID / UUID formatting and won't accept NanoID without custom handling.
- Database indexing: NanoID generates random strings, which can cause index fragmentation similar to UUID v4. For database primary keys, consider UUID v7.
- Size customization risks: Using smaller NanoID sizes (e.g., 10 characters) significantly increases collision probability. Always validate the required entropy for your use case.
- Random number generator quality: NanoID security depends on the underlying random number generator. Ensure you're using cryptographically secure randomness (Node.js crypto, Web Crypto API).
- Migration complexity: switching from one identifier format to another in an existing system can be challenging and may require data migration.
- Interoperability matters: if you work across many systems or languages, GUIDs / UUIDs typically win due to universal support and standardization.
Frequently Asked Questions
No. NanoID is a different identifier format with variable length (default 21 characters) and URL-safe encoding. It's not governed by
RFC 9562. If you need a standards-based GUID / UUID, prefer
v4 or
v7.
More efficient encoding. NanoID uses a URL-safe alphabet (64 characters: A-Za-z0-9_-) which encodes more information per character than UUID's hexadecimal (16 characters: 0-9a-f). Additionally, NanoID omits hyphens and uses a compact representation, resulting in 21 characters vs UUID's 36 characters for similar entropy.
For most systems,
GUID / UUID v7 is the best choice because it provides time-ordering, native database support, and efficient binary storage (16 bytes).
NanoID stored as VARCHAR (21+ bytes) is less efficient and lacks native database indexing optimizations. For simple universal IDs,
GUID / UUID v4 remains widely used.
No. NanoID and GUID / UUID have completely different structures, encodings, and formats. You cannot losslessly convert between them. Choose one format for your system and stick with it for consistency. Migration requires generating new IDs and maintaining mapping tables if you need backward compatibility.
The
default 21 characters provides ~126 bits of entropy, sufficient for most applications. Use the
NanoID collision calculator to determine the right size for your needs. For reference: 21 chars = ~150 trillion IDs for 1% collision probability. Shorter IDs increase collision risk exponentially.
For identifiers, yes. NanoID uses cryptographically secure random number generation (crypto.randomBytes in Node.js, Web Crypto API in browsers). However, like all IDs, NanoID is an identifier, not a security token. Don't use it as a password, authentication secret, or encryption key. For security-critical tokens, use dedicated libraries and longer lengths.
Yes. NanoID has ports for many programming languages including Python (nanoid), Go (gonanoid), Ruby (nanoid), Rust (nanoid), C# (Nanoid-net), and more. However, these are community ports, not official standard library implementations. For maximum cross-language compatibility, use
standard GUIDs / UUIDs.
Yes. NanoID has excellent browser support and uses the Web Crypto API for secure random number generation. It's widely used in React, Vue, Angular, and other frontend frameworks for generating client-side identifiers, temporary IDs, and component keys. The tiny bundle size (~100 bytes) makes it ideal for web applications.
Choose
UUID v4 when you need maximum interoperability, standards compliance (
RFC 9562), native database support, or when working across multiple programming languages and platforms. Choose
NanoID when size matters (URLs, QR codes), you're primarily in JavaScript/TypeScript, and you need the smallest possible URL-safe identifier.
Yes. NanoID supports custom alphabets through the customAlphabet function. You can use lowercase-only, numbers-only, or any character set you need. However, changing the alphabet affects collision probability and entropy calculations. The default URL-safe alphabet (A-Za-z0-9_-) is recommended for most use cases to maintain 6 bits per character.
Conclusion
For broad interoperability and standards compliance, choose a standard GUID / UUID: v4 for general-purpose fully random IDs or v7 for time-ordered database-friendly identifiers with millisecond precision.
Choose NanoID when you need compact, URL-safe identifiers for web applications, short URLs, or JavaScript-heavy systems where size and performance matter. However, be aware that you'll sacrifice standards compliance, native database support, and cross-platform consistency compared to standard GUIDs / UUIDs.